This month’s open thread on climate topics. Impending El Niño, fossil fuel funded wedges, retirements, heat waves, and the same old, same old, from the usual suspects. Try to discuss these things calmly!
Reader Interactions
169 Responses to "Unforced Variations: July 2026"
Comment Policy:Please note that if your comment repeats a point you have already made, or is abusive, or is the nth comment you have posted in a very short amount of time, please reflect on the whether you are using your time online to maximum efficiency. Thanks.
Zebra: “Do you really think what you just wrote is useful,…”
I’m sorry, Zebra. When I was an editor, they allowed us to make the assumption that our audience was literate. If you like, I can try to write something at your level–perhaps with bigger words and lots of pictures on the page?
Ray, I’m with Pascal on this. I think you should take the time to write a shorter letter, which you obviously don’t. You know, edit thyself.
I also think 99% of the population would greatly benefit from fewer words and lots of pictures in understanding and relating to science. People can be very “literate” without knowing or understanding jargon in a specialty, or even knowing that Physics Today exists, much less reading it.
My experience tells me that the first step in educating someone is listening to them and understanding “where they are at”; lecturing them at your own level isn’t going to help them move forward… usually the opposite.
https://www.realclimate.org/index.php/archives/2025/11/unforced-variations-nov-2025/#comment-842186 , https://www.realclimate.org/index.php/archives/2026/06/unforced-variations-june-2026/#comment-849365 , https://www.realclimate.org/index.php/archives/2026/04/a-reflection-on-reflection/#comment-848619 :
k_{a,air} = μ_{a,air} ÷ ρ_{air} = ∑_i ( n_i · σ_{a,i} ) ÷ ρ_{air}
n_i = number density of i
——————————————–
My understanding is that the ratios of the rates of spontaneous emission, stimulated emission, and direct absorption, are, at LTE/LEDNLIE (Local Equilibrium Distribution of Non-Latent Internal Energy), determined by T (and ν and …) via the ratio of the populations of particles in states 2 and state 1 (where E₂ – E₁ = E₂₁ ); this is easiest to show for distinguishable particles which (at LTE/LEDNLIE) fit a Maxwell-Boltzmann distribution:
Maxwell-Boltzmann distribution: population in state 2 / population in state 1 = exp[ − E₂₁ / (kT) ]
But I expect it works out more generally (eg.
https://www.realclimate.org/index.php/archives/2024/10/unforced-variations-oct-2024/#comment-826352 )
@ LTE/LEDNLIE, for the optical transitions between a pair of states1 and 2, the absorption cross section σ_a is the blackbody area that would (given a spectral radiance L_ν from a direction) absorb at the same rate as the average per particle (eg. over all CO2 molecules of a given isotopologue) rate of “total absorption” = direct absorption − stimulated emission. If you take the average per particle rate of spontaneous emission and fit it into the absorption cross section σ_a, you get the Planck function.
I *believe* collisions act like observations of a quantum system eg. molecule; in isolation, during a transition between a pair of states, the system is in an evolving superposition of the states. So collisions turn this into a probability; eg. if they occur when the transition is 1% of the way done, then 99% of the transitions are aborted, but the 1 % that occur have been forced to happen 100 times faster (causing collisional line broadening), so the overall transition rates – and thus rates of spontaneous emission, stimulated emission, and direct absorption – are unchanged.
optical depths τ from O2 and N2:
https://en.wikipedia.org/wiki/Rotational%E2%80%93vibrational_spectroscopy#Homonuclear_diatomic_molecules :
“I *believe* collisions act like observations … but the 1 % that occur have been forced to happen 100 times faster (causing collisional line broadening), so the overall transition rates – and thus rates of spontaneous emission, stimulated emission, and direct absorption – are unchanged.” … Well, the math might be more complicated than that, but somehow it must work out that GHG molecules emit photons even when at LTE. – because Schwarzchild’s eqn.
dL = (B – L) dτ
works:
https://en.wikipedia.org/wiki/Schwarzschild%27s_equation_for_radiative_transfer
https://scienceopinionsfunandotherthings.wordpress.com/2025/12/09/for-asymptotic-radiances-ppia-linear-and-general-cases-wip-awaiting-final-proofread-double-check-diagrams-pending/ , https://scienceopinionsfunandotherthings.wordpress.com/2025/12/24/for-asymptotic-radiances-ppia-linear-b%cf%84/
re Ray Ladbury https://www.realclimate.org/index.php/archives/2026/06/unforced-variations-june-2026/#comment-849480
but often enough to approximately maintain an excited population of each type of GHG molecule. In fact there will even be a tiny fraction which are excited above the lowest excited vibrational state (for each mode of vibration) (I think/infer that ‘hot bands’ are significant contributors on the wings of the CO2 band). (This is in accordance with the LTE approximation.) And occasionally they will manage to emit a photon before a collision.
No, that’s wrong. For isotropic σ_a:
Net spectral radiant cooling per unit mass = 4π · ( B − L_{4π} ) · k_{a,air}
Ie.
Net spectral radiant cooling per particle (averaged for each type of particle (eg. over all CO2 molecules of a given isotopologue)) = 4π · ( B − L_{4π} ) σ_a
Ie.
it’s the difference between 4π · σ_a · the Planck function (spontaneous emission) and the 4π · σ_a · directionally averaged ambient radiance (absorption).
Ie. it depends on being able to see across a difference in T.
And the troposphere on average must experience net LW radiant cooling to balance SW heating and convergence of the convective heat flux from the sfc.
See https://www.realclimate.org/index.php/archives/2026/04/a-reflection-on-reflection/#comment-848619 :
https://www.realclimate.org/index.php/archives/2026/06/unforced-variations-june-2026/#comment-849508 :
Corrected/fixed:
“(I think/infer that ‘hot bands’ are significant contributors on the wings of the CO2 band)” – Oops! No, not quite:
https://rmets.onlinelibrary.wiley.com/doi/10.1002/qj.4485
“Radiative forcing due to carbon dioxide decomposed into its component vibrational bands†”
Keith P. Shine, Georgina E. Perry
(I think I read sec. 2 through perhaps the end of 3.1 (?) )
(background – see https://en.wikipedia.org/wiki/Rotational%E2%80%93vibrational_spectroscopy ,
CO2: https://en.wikipedia.org/wiki/Rotational%E2%80%93vibrational_spectroscopy#Polyatomic_linear_molecules ,
https://en.wikipedia.org/wiki/Rotational_spectroscopy
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Spectroscopy/Vibrational_Spectroscopy/Vibrational_Modes/Combination_Bands_Overtones_and_Fermi_Resonances )
Although those ‘wing-’bands do involve transitions between pairs of states in which the lower energy state is a bending-mode (v_2) vibrationally-excited state; some even being the second such excited level** (and
thusso I’d expect the overall band (assemblage of bands) will be effectively wider/narrower at higher/lower T – and of course the same is true of each individual band because of the distribution of CO2 among rotational states …(T = 0 K should collapse the entirety of the band into just two lines (1 in R-branch and 1 in Q-branch) per isotopologue, I expect)
…– so I’d expect the effective widening (window closure) would be more/less per doubling of CO2.
**Also it turns out that the 1st excited bending-mode energy level has a degeneracy (g) of 2 – and I’m guessing, based on some logic, that the degeneracy of the n-th level of the bending-mode (where ground n = 0) will be n+1 (?); so the populations
(in (v_1, v_2 , v_3) = (x, n, z) , setting aside the Fermi-resonance states (correct phrasing?))
would then be proportional to
(n+1 [?]) exp[ −E_n / (kT) ]
(- me @ https://www.realclimate.org/index.php/archives/2024/10/unforced-variations-oct-2024/#comment-826352 )
Which means ≈ 8.17 % is the ratio of the populations in the corresponding levels. Note that this is a ratio; the fraction of CO2 molecules in v_2 = 1 will be smaller, ie.
≈ 8.17 % / [ ∑ ( 100 % + 8.17 % + … )]
Anyway, my ballpark est. of the rate of spontaneous emission from CO2 v_2 = 1 → 0 (which was… where is that comment?) would have been ~doubled if I had known this.
“Although those ‘wing-’bands do involve transitions between pairs of states in which the lower energy state is a bending-mode (v_2) vibrationally-excited state; some even being the second such excited level**”
– or state of similar energy, judging from Fig.2 (see the FF transitions)
“Which means ≈ 8.17 % is the ratio of the populations in the corresponding levels.”
– @ 300 K.
“(I think/infer that ‘hot bands’ are significant contributors on the wings of the CO2 band)” – Oops! No, not quite:
https://rmets.onlinelibrary.wiley.com/doi/10.1002/qj.4485
“Radiative forcing due to carbon dioxide decomposed into its component vibrational bands†”
Keith P. Shine, Georgina E. Perry
(I think I read sec. 2 through perhaps the end of 3.1 (?) )
(background – see https://en.wikipedia.org/wiki/Rotational%E2%80%93vibrational_spectroscopy ,
CO2: https://en.wikipedia.org/wiki/Rotational%E2%80%93vibrational_spectroscopy#Polyatomic_linear_molecules ,
https://en.wikipedia.org/wiki/Rotational_spectroscopy
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Spectroscopy/Vibrational_Spectroscopy/Vibrational_Modes/Combination_Bands_Overtones_and_Fermi_Resonances )
Although those ‘wing-’bands do involve transitions between pairs of states in which the lower energy state is a bending-mode (v_2) vibrationally-excited state; some even being the second such excited level**
– or state of similar energy, judging from Fig.2 (see the FF transitions) –
(and
thusso I’d expect the overall band (assemblage of bands) will be effectively wider/narrower at higher/lower T – and of course the same is true of each individual band because of the distribution of CO2 among rotational states …(T = 0 K should collapse the entirety of the band into just two lines (1 in R-branch and 1 in Q-branch) per isotopologue, I expect)
…– so I’d expect the effective widening (window closure) would be more/less per doubling of CO2.
**Also it turns out that the 1st excited bending-mode energy level has a degeneracy (g) of 2 – and I’m guessing, based on some logic, that the degeneracy of the n-th level of the bending-mode (where ground n = 0) will be n+1 (?); so the populations
(in (v_1, v_2 , v_3) = (x, n, z) , setting aside the Fermi-resonance states (correct phrasing?))
would then be proportional to
(n+1 [?]) exp[ −E_n / (kT) ]
(- me @ https://www.realclimate.org/index.php/archives/2024/10/unforced-variations-oct-2024/#comment-826352 )
Which means ≈ 8.17 % is the ratio of the populations in the corresponding levels [@ 300 K]. Note that this is a ratio; the fraction of CO2 molecules in v_2 = 1 will be smaller, ie.
≈ 8.17 % / [ ∑ ( 100 % + 8.17 % + … )]
Anyway, my ballpark est. of the rate of spontaneous emission from CO2 v_2 = 1 → 0 (which was… where is that comment?) would have been ~doubled if I had known this.
Also,
“Why the Forcing from Carbon Dioxide Scales as the Logarithm of Its Concentration” David M. Romps, Jacob T. Seeley, Jacob P. Edman
https://journals.ametsoc.org/view/journals/clim/35/13/JCLI-D-21-0275.1.xml
sec. 5c. “Linearity of κ in pressure”:
κ = S(T) / (π·γ) · γ² / [ γ² − ( ν − ν_c)² ]
can be rewritten as:
κ = S(T) / (π·γ) · 1 / [ 1 − ( ∆ν / γ )² ]
∆ν = ν − ν_c
Their absorption coefficient κ has units of m²/mol (caption of fig. 7), which is thus the absorption cross section σ_a per molecule, multiplied by Avogadro’s number.
So the integral ∫ κ dν for the line is constant over variations in collisional line broadening (γ = line width) – at least for a Lorentz line shape – which
may beis an approximation**, but maybe there’s other p-related things going on (eg. tiny amounts of quasi-static p-broadening?).Ie, at least approximately, and except for the effects of the curvature of Planck function over ν (should generally be tiny over γ), the rates of spontaneous emission and total absorption (direct absorption − stimulated emission) should be conserved over variations in collisional line broadening.
(PS I’m using ν, the symbol for frequency, because that’s a whole lot easier to write in this space than the notation for spectroscopic wavenumber, but that’s what I’m really referring to (they are proportional)).
Note the T-dependence of the distribution of molecules of a given type among their possible states is, *I believe*, the mechanism for the T-dependence of the line strength (the quantity that is, AIUI, conserved over variations in line broadening); this includes changing the stimulated emission/direct absorption ratio. This is separate from thermal Doppler broadening.
** sec. 5c. “Linearity of κ in pressure”:
Oops!
– For a given T, and (for absorption) a given directionally averaged ambient spectral radiance L (≡L_{4π}; for isotropic σ_a), which of course can be changed by line broadening (reduced opacity at/near the center (you can see farther), & exposure to L over a larger bandwidth, including bandwidth where you can see farther).
PS AIUI, collisional line broadening, like natural broadening, is due to the finite time over which a photon is emitted or absorbed. A wave packet is mathematically composed of a superposition of a range of frequencies and wavelengths (or wavenumbers or wave vectors in 3D); a wave packet that is more concentrated into a shorter time or smaller space must be composed of a larger range of frequencies (proportional to E) or wave vectors (proportional to momentum).
( “The more general uncertainty principle, regarding Fourier transforms” – 3Blue1Brown https://www.youtube.com/watch?v=MBnnXbOM5S4 )
I think somebody last month asked about the photons being in LTE with the air – so to clarify, they generally are not expected to be. In this context, the LTE/LEDNLIE pertains to the energy distribution over the non-photons* of the air and sfc. (molecules, atoms, ions(? – in solution or solid/liquid…), electrons…) *-we can exclude the neutrinos, too…
The point is that the GHGs and cloud particles/etc. all (in the vast majority of the mass of the atmosphere) have access to a locally (small volume)-shared reservoir of enthalpy and therefore internal energy (we needn’t be concerned about what counts as thermal energy if we just refer to internal energy) ((approximately) LTE → internal energy distributed such that each statistically-sufficient substance has (approximately) the same T, and etc…) which they can add to and take from by absorbing and emitting photons.
See also https://www.realclimate.org/index.php/archives/2026/06/unforced-variations-june-2026/#comment-849365
Well, it will be harder to approximately maintain and isothermal relationship among the air and it’s resident aerosols because of the need to conduct heat to/from one to the others if the net radiant cooling per unit heat capacity varies and/or latent heat is being released/taken up (cloud particles), but it may still involve an approximate LTE/LEDNLIE on smaller scales? (how many molecules are in a r = 5 µm droplet…?)
But the other thing is of course that @ LTE/LEDNLIE, the internal energy (kinetic and potential energy of the relative motions and arrangements of atoms/electrons/etc.) is distributed such that the populations of particles in states of various energies support relationships among the rates of direct absorption (per unit spectral radiance L), − stimulated emission (per unit spectral radiance L), and spontaneous emission, such that, after stimulated emission cancels out some direct absorption, what remains…
(me @ https://www.realclimate.org/index.php/archives/2025/11/unforced-variations-nov-2025/#comment-842186 )
And the visible (not hidden) cross-sectional area that you can see (in some direction) from a given POV (location) is the radiating surface producing the spectral radiance L_ν = B_ν of radiating surface (coming from that direction); L_ν = B_ν of radiating surface – but within the atmosphere, that surface is distributed over distance s along the line of sight (LOS); so I …
Shorter version – the thicker the ‘fog’, the less far you can see. And you need to be able to see across a difference in T in order to have a net spectral flux density … etc.
Martin Smith
Martin, you said:
“Ray, aren’t you describing the warming of the atmosphere? I thought the warming is not the greenhouse effect, but the effect of the greenhouse effect.
The greenhouse effect is:
1. Blocking energy emitted from the surface, and
2. Sending blocked energy back to the surface.
Between 1 and 2, the blocked energy warms the atmosphere, so global warming is the effect of the greenhouse effect.
Have I had it wrong all along?”
Earlier, I said that a simplified explanation is a good thing, but it requires being careful. You still have to be precise and disciplined in your language, or you confuse your reader and yourself.
“The greenhouse effect” refers to the energy retained by the climate system when GHG absorb radiant energy and convert it to thermal energy.
“Global warming” refers to the increase in average surface temperature resulting from the increase in that thermal energy resulting from human-caused increase in GHG.
In my opinion, what I just wrote is what you say you are looking for. A simplified, mechanistic explanation of the GHE, as well as “global warming”.
What more do you want to know? I can explain the terms radiant energy and thermal energy, or would you like to hear how this all applies to the expression “climate change”?
(That last was obviously me pretending to be your AI friend.)
Zebra: “The greenhouse effect” refers to the energy retained by the climate system when GHG absorb radiant energy and convert it to thermal energy.
“Global warming” refers to the increase in average surface temperature resulting from the increase in that thermal energy resulting from human-caused increase in GHG.
In my opinion, what I just wrote is what you say you are looking for. A simplified, mechanistic explanation of the GHE, as well as “global warming”.
MS: Your explanation confuses me more. A greenhouse traps energy, so a mechanistic explanation of the GHE must explain how the energy is trapped.
The mechanistic explanation of global warming must explain how the trapped energy warms the atmosphere.
Martin,
1. I said:
“GHG (greenhouse gasses) absorb radiant energy and convert it to thermal energy.”
Radiant energy can escape to space, but thermal energy cannot. Hence, the energy is “trapped”.
2. I said:
““Global warming” refers to the increase in average surface temperature resulting from the increase in that thermal energy resulting from human-caused increase in GHG.”
Thermal energy is what determines the temperature. If you increase thermal energy, the temperature will increase. “Warming” is by definition an increase in temperature.
Feel free to ask anything about what is still confusing you.
I understand what you are saying, Zebra, I just don’t think you are saying it right. I’m trying to say that the greenhouse effect and the warming are separate mechanisms.
1. The absorption by the GHG (i.e. trapping) of the radiant energy emitted from the surface is the GREENHOUSE EFFECT.
2. The conversion of the absorbed (i.e. trapped) radiant energy to thermal energy is WARMING.
3. The increase in WARMING averaged for the entire globe that results from increasing GHG, which then increase 1 and 2, is GLOBAL WARMING.
If I am confused it is about absorption vs conversion to thermal energy. Are absorption and conversion 2 sequential steps or are they a single step?
Martin
Here’s what NASA says;
“What is Global Warming?
Global warming is the unusually rapid increase in Earth’s average surface temperature over the past century primarily due to the greenhouse gases released as people burn fossil fuels. The global average surface temperature rose 0.6 to 0.9 degrees Celsius (1.1 to 1.6° F) between 1906 and 2005, and the rate of temperature increase has nearly doubled in the last 50 years. Temperatures are certain to go up further.”
“Warming” refers to an increase in temperature. Always has.
ms, in #3 you are correctly (more or less) describing the enhanced greenhouse effect.
An increase in the concentration of greenhouse gases leads to an increased infrared opacity of the atmosphere, and therefore to an effective radiation into space from a higher altitude at a lower temperature. This causes a radiative forcing, an imbalance that can only be compensated for by an increase of the temperature of the surface-troposphere system. This is called the “enhanced greenhouse effect.”
see under Greenhouse Effect
https://archive.ipcc.ch/ipccreports/tar/wg2/index.php?idp=689
# 1 & 2 are off. see my other comments and ipcc ref
also note more semantics confusion – warming of the surface is the result of the greenhouse effect.
global warming is a “yardstick measurement” to estimate mathematically the change in avg surface temperatures calculated on a baseline … over time … bpl is (more or less ) right but most people cant read greek or math.
the issue here remains problematic from trying to oversimplify beyond reason.
Martin, I’ll try again. To start with, you have so-called “black-body radiation”. This is thermal radiation with the amount of radiation and its spectrum characterized solely by the object’s temperature. A pure-black object absorbs all radiation incident upon it (a perfect absorber)–and it is also a perfect emitter. In reality, a perfect blackbody emitter is like a spherical cow–an idealization. That is why you hear Earth sometimes referred to as a “gray body”–it’s not important for out purposes–a blackbody is a pretty fair approximation. For bodies near 273 K, blackbody radiation peaks in the infrared–heat radiation.
So Earth in a vacuum or with inert atmosphere absorbs visible radiation coming in and emits IR going out, and reaches an equilibrium temperature. Now add a greenhouse gas. This is just a molecule that absorbs in that peak portion of the blackbody spectrum–in the IR. For a molecule to do this, it has to be at least triatomic–N2, O2 won’t do it. So, now, you have a molecule taking a bite out of the blackbody emission spectrum in the IR and getting excited into its vibrating state.
But when a molecule gets excited, it will eventually relax back into its ground state. A CO2 molecule can do so in a couple of ways–it can emit a photon of the same energy it absorbed to trigger the vibration or it can collide with a (say) N2 molecule and impart kinetic energy from the vibration to the N2 molecule. For CO2, the lifetime before it emits a photon is quite long. So as long as atmospheric densities are high enough, a relaxation by collision is far more likely than radiating a photon. That is what is meant by “thermalizing the energy”.
There is one additional thing to consider–the temperature gradient. If temperatures decrease with altitude as in the troposphere, CO2 molecules at high altitude are much less likely to become excited by collision, and so even less likely to relax by emitting a photon. (In the stratosphere, the temperature gradient reverses sign, so you get more emission by radiation and more IR escaping the stratosphere and so cooling. Both of these are in fact due to the greenhouse effect.)
You can think of equipartition as how a system shares energy among its different modes. In equilibrium, the modes are all at the same temperature–it’s like a series of connected reservoirs all at the same level. Now we pour some energy into the reservoir marked “excited CO2”. The system is out of equiliburium, and energy flows into the other modes of the system (e.g. the kinetic energy/temperature of N2, O2 and other atmospheric gasses). It’s not just absorption and re-radiation.
Does that help?
RL: Does that help?
MS: No. I mean, I understand it, and I appreciate it, but it is too long-winded to be what used to be called an elevator explanation. The NASA explanation Zebra posted tries to be a meme, but it doesn’t explain because it simplifies away the explanation.
The simplified mechanistic explanation has to be clear enough, short enough, and long enough so it can be used as your opening when you pitch your idea for a TV series about the greenhouse effect to producers who don’t know physics and who will shoot your idea down with memes like “CO2 has been high before,” “The Medieval Warm Period was global,” and “CO2 is a trace gas.”
in Re to Ray Ladbury, 6 Jul 2026 at 12:33 PM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849581
Dear Ray,
To be honest, I have no idea what you have tried to explain in the last paragraph of your comment, specifically in the sentences
“In equilibrium, the modes are all at the same temperature–it’s like a series of connected reservoirs all at the same level. Now we pour some energy into the reservoir marked “excited CO2”. The system is out of equiliburium,”
I think that in Earth atmosphere, the real distribution of available energy states of various air components does, in fact, almost perfectly fit the theoretical “equilibrium” distribution expected on the basis of the actual temperature in the respective air parcel. Exceptions could perhaps occur e.g. in rare cases of injection of energetic particles into upper atmosphere by solar storms or during electric discharges, I suppose. It appears, however, that you meant something much more generic. Could you clarify?
Greetings
Tomáš
Think of it as sequential steps:
1) The CO2 molecule in its ground state
2) The CO2 molecule is excited into its vibrational state
a) this can happen because it absorbs a photon of the right wavelength
b) or it can happen because a collision with another molecule imparts energy to excite the vibration
3) The CO2 molecule relaxes
a) by emitting a photon of the right wavelength
b) by imparting the kinetic energy from its vibration to another molecule via collision
Note the symmetry between 2 and 3. BUT in Earth’s atmosphere, temperatures are sufficiently low that it is rare that a molecule has sufficient energy to excite the vibration (e.g. 2b)). So the flux of blackbody radiation near 15 microns represents a flow of energy that excites the CO2 vibrations.
Likewise, the symmetry in 3 is also broken, because the lifetime of the relaxation process via photon emission is quite long. During that lifetime, a molecule is likely to collide with many molecules, at least one of which causes the CO2 molecule to return to its unexcited ground state. (3b more likely than 3a).
The CO2 in the atmosphere does still emit 15 micron photons–just what you’d expect it to emit for a blackbody at the temperature prevalent at the molecule’s altitude. Near the ground, atmospheric densities and CO2 concentrations are high enough that the probability of a 15 micron (+/- a micron or so) escaping the atmosphere is essentially nil. Only the 15 microns emitted at higher altitude/lower density/lower temperature have a reasonable probability of escaping.
This is the basic flow of energy due to the greenhouse mechanism that is responsible for the imbalance that raises tropospheric temperatures. But as I said, it’s the basics. There are lots of nuances–and if you omit these little nuances or don’t understand them properly, you can get stuck.
This is why the same denialist can claim that a trace gas like CO2 can’t possibly warm the atmosphere AND that greenhouse warming is impossible because the CO2 absorption is saturated. This is why I think it is a mistake to try to oversimplify the greenhouse effect. It took scientists over 100 years to fully understand all the subtleties of the effect. The first-principle quantum-mechanical calculations demonstrating why the CO2 absorption band is NOT saturated were only done in the last few years. If you wanted to pitch a series to a bunch of Hollywood jerkwads with short attention spans, the discovery process would be the script to pitch.
RL:
1) The CO2 molecule in its ground state
2) The CO2 molecule is excited into its vibrational state
a) this can happen because it absorbs a photon of the right wavelength
b) or it can happen because a collision with another molecule imparts energy to excite the vibration
3) The CO2 molecule relaxes
a) by emitting a photon of the right wavelength
b) by imparting the kinetic energy from its vibration to another molecule via collision
MS: That’s a mechanistic explanation for what happens to a CO2 molecule, but…
It says the molecule is in its ground state. That must be the state it is in when it is on the ground.
The molecule gets excited. It starts vibrating when it gets excited, so it wasn’t vibrating at all before it got excited.
The molecule can get excited if it absorbs a photon of the right wavelength. When it absorbs a photon of the wrong wavelength, it doesn’t get excited.
And the CO2 molecule can relax, if it emits a photon of the right wavelength, but if it emits a photon of the wrong wavelength, it stays excited.
Or, the molecule can relax if it collides with other molecules, which doesn’t sound very relaxing at all. More like aggravating.
I understand your mechanistic explanation of what happens to a CO2 molecule throughout the GHE/warming cycle, but a person who rejoices in the acronym MAGA will get tripped up in all the ways I listed.
And I think a mechanistic explanation of the path of energy through the GHE/warming system is a better way to explain it, but maybe both points of view works even better.
Um, not quite. “Warming” is by definition an increase in thermal energy. Temperature is merely the yardstick being used to record the level of that thermal energy in space and time.
The drive to make this short and simple is creating errors. Occam’s-razor warns against the error of oversimplifying past the point of accuracy. The simplest accurate model of necessary mechanisms is still the minimum required.
“Global warming is the rise in surface temperature caused by the build-up of thermal energy (originally from the Sun) in the climate system, due to human-emitted greenhouse gases trapping more of that energy.”
That’s accurate but it may not be addressing the dynamics of how it happens which people want to express.
A more scientifically precise way to say it:
“Global warming refers to the increase in Earth’s average surface temperature resulting from the build-up of thermal energy (originally from the Sun) in the climate system, caused by human-increased greenhouse gases slowing the escape of outgoing infrared radiation to space.”
Moreover, the thermal energy itself doesn’t “escape” to space; it is radiated away. So, the energy isn’t “trapped” like a blanket traps heat by physically holding it in place. Rather, greenhouse gases slow down the leak of energy to space. And it’s that which causes the build-up of thermal energy (originally from the Sun) in the climate system in the first place.
The increase in greenhouse gases today has forced the increase of thermal energy and therefore the temperature. But if are being forced to condense all of that into a single, final, punchy statement that can’t really be argued with, you could say:
“The simplest accurate model is this: more GHGs slow the escape of the Sun’s energy to space, causing thermal energy to build up, which raises surface temperature. Anything simpler than that omits the actual mechanism and becomes misleading.”
This discussion is circular. The IPCC already covered the basics long ago: Frequently Asked Question 1.3 What is the Greenhouse Effect?
https://archive.ipcc.ch/publications_and_data/ar4/wg1/en/faq-1-3.html
Trying to simplify it further destroys it’s meaning and the physics involved. Embrace the complexity.
Kobayashi Maru,
I think the ‘GHE is not like a blanket’ idea you present is not helpful for explaining GHE. Blankets (with the exception of impervious ‘space blankets’) physically leak like sieves. The troposphere presents a far-less leaky barrier for the air of planet Earth than a blanket-enwrapped human. The journey for a packet of air from ground up to the tropopause takes on average perhaps a couple of weeks. That’s [ 9/(2 x 186) =] 0.024 mph or 0.01m/s. Blankets (okay not an apple-with-apples comparison) are measured with a permeability of perhaps 0.5m/s.
Unlike your assessment, I rather liked Zebra’s simplistic idea that “Radiant energy can escape to space, but thermal energy cannot. Hence, the energy is “trapped”.” Indeed, you say it yourself. “The thermal energy itself doesn’t “escape” to space; it is radiated away.” One of the things us small-brained mammals have yet to figure out is the nature of the photons that comprise radiation. But we do know for sure it ain’t not “thermal energy.”
And while I would make an issue of what is the sun’s energy and what is the Earth’s energy, your statement “More GHGs slow the escape of the Sun’s energy to space,” still doesn’t explain why that is the case. What is the ‘slowing’ mechanism?
To give my six-pen’orth, I’d also point out (1) Radiation is how energy flows into and out of objects floating in space. Actual thermal energy is indeed trapped and needs converting into radiation to exit the planet.
But then I’d add that (2) It is the temperature of that object which determines the ‘conversion to radiation’ and thus the amount of radiated energy shot out into space. Higher temperature means higher radiation out. Specifically, this is about the temperature of the ‘areas’ that radiate into space. Without an atmosphere or a GHG-free atmosphere, the ‘area’ in question will always be the object’s surface.
And from there (3) GHGs result in a shift in the ‘area’ specific to the wavelength of radiation the GHGs absorb/emit. More GHGs, the higher that ‘area’.
(4) Because the Earth’s troposphere gets colder with height, that means more height for a GHG’s ‘area’, less temperature in that ‘area’, less radiated energy out from Earth.
(5) The Earth will then begin to heat, increasing temperature until the resulting increased radiation from that increased temperature equals the GHG-induced reduction in radiation.
That is the basis of how GHGs work. I can’t think of a simpler explanation that doesn’t resort to the ‘blanket’ or the ‘greenhouse’ analogy. (And do note, like blankets, operating greenhouses are remarkably leaky things although they call it “ventilation” not permeability’.)
Sadly the workings of the GHE mechanism is not well described outside scientific discussion. That IPCC AR4 page you link-to spends 670 words answering the question ‘What is the Greenhouse Effect?’ but of the underlying mechanism it only manages to tell the reader that it operates like a greenhouse although “through a different physical process” and that “adding more of a greenhouse gas, such as CO2, to the atmosphere intensifies the greenhouse effect, thus warming Earth’s climate.” Sure there’s a lot of other information provided answering the question but by 2007 the continued “It’s like a greenhouse” explanation was (and today remains) entirely inadequate in the face of blatant denialistic bullshit from far too many ‘authorities’ who should know better.
‘MA Rodger
I believe I am correct. The IPCC is accurate. The physics is right. I’ll defer to the IPCC links I gave but will add the following brief clarification.
Anyone involved around climate change science and global warming, like I have for 30-40 years, understands that global warming is a metaphor, the greenhouse effect is a metaphor and the blanket idea is an analogy to explain those metaphors to the public at large.
Fully aware they are imperfect metaphors and analogies, knowing full well they are unsatisfactory from a purist science pov and yet all have been used repeatedly by renowned physicists to explain parts of the complex climate science, the physics and the mechanisms surrounding the ideas behind the greenhouse effect and the enhanced greenhouse effect; the difference between thermal energy, warming, and global warming and why temperature is different entity, since Syukuro “Suki” Manabe was a boy.
I’m quite happy with my explanations as far as they go. Knowing they were provided to only answer MS’s very specific question. They were not intended to explain the entirely of the physics behind 6 IPCC assessment reports. It’s complicated. I was trying to help where others had failed.
Thanks for your interest. I’m humbled.
Martin Smith: A person who calls themselves MAGA is ineducable and irremediably stupid or they wouldn’t be MAGA to begin with. They don’t recognize facts or truth or science. If the person is not interested in the science, they won’t be perusaded by the science, particularly when it counters their accepted world view.
Learning is only possible for those who have not achieved epistemic closure.
In Re to zebra, 3 Jul 2026 at 6:01 AM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849546 ,
and Martin Smith, 2 Jul 2026 at 10:18 AM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849535
Dear zebra,
There is no clear generic relationship between “energy” of a system and its temperature. An example: If a bottle filled with ice absorbs heat from its surrounding, its thermal energy increases, however, its temperature remains constant until all the ice melts.
Dear Martin.
The average radiative temperature of Earth surface (that can be computed, according to Stefan-Boltzmann law, from the average intensity of the upwelling infrared radiation flux) depends on a time and space average of a complex balance of a multiplicity of various energy fluxes across the surface and the atmosphere. These global balances are usually depicted in “energy budget” diagrams called also Trenberth’s diagrams. Basically, any external perturbation to any of these particular fluxes, including a change in the atmospheric concentration of a greenhouse gas, may perturb the entire system. Examples of such induced perturbations may be the rising global average surface temperature and the decreasing temperature in the lower stratosphere induced by rising atmospheric carbon dioxide concentration. The fluxes in the corresponding diagram change accordingly. In absence of external perturbations, a steady state can be reached,
As regards the complex mechanism of the “greenhouse effect” of the atmospheric gases absorbing the infrared radiation, and/or of the changes in the altitude / temperature profile induced by changes in the greenhouse effect intensity, I recommend rather relying on explanations provided by standard textbooks (like Physical Climatology by professor Dennis Hartmann), by people like patrick o twentyseven or MA Rodger, or by a good AI engine, than striving to decrypt and/or correct confusing statements released by zebra.
Greetings
Tomáš
Martin Smith (MS) 25 Jun 2026 at 3:24 AM “I need a correct, simplified, mechanistic explanation using photons, molecules, kinetic energy, and words like ground, ocean, re-emit, and back radiation”. Following after a delineation line of “+” signs below is a perfectly-correct, sufficiently-complete simplified, mechanistic explanation of the so-called “greenhouse effect (GHE)” in Earth’s troposphere which avoids some of the MS words that I quoted because they are incorrect or misleading, or unnecessary for a full simplified, CORRECT mechanistic explanation. The simplified, mechanistic explanation is 4 short paragraphs with simple, obvious concepts that describe the operation followed by Notes that aren’t required for the simplified, mechanistic explanation but might be interesting. Preceding that are comments on what I infer are 2 significant misunderstandings by MS which appear to closely relate to each other (the same basic misunderstanding of MS).
=======
MS appears to think that GHE is solely due to change in “atmospheric window frequencies” (MS 27 Jun 2026 at 2:13 PM “Google AI …… is 10% to 15%) but GHE certainly isn’t much at all to do with “10% to 15%” in the atmospheric window, except maybe during Snowball Earths not at all relevant now. That “blocking effect” is a small bit player, a nibble at the edges right around 8.0 microns for H2O gas, 9.0 & 10.0 for O3, and 13.0 for CO2 as seen for example at 17:10 at my UTube video link below (Side Note: It’s shown as a lesser amount for CO2 increase than used by NASA but that’s an advanced matter that I’ll never study and certainly irrelevant to the “simplified, mechanistic explanation”).
MS 30 Jun 2026 at 1:00 PM “The greenhouse effect is:”
1. Energy emitted by the surface is blocked
2. Blocked energy is sent back to the surface”
30 Jun 2026 at 12:45 PM “The greenhouse effect is:
1. Blocking energy emitted from the surface, and
2. Sending blocked energy back to the surface”.
=======
Nope, that wouldn’t work as stated because the temperature lapse rate caused by reduced pessure with altitude wasn’t mentioned and that’s what makes it work. (my entire point I’ve made since 2018 about the confusion sowed about something simple by misleading and incomplete, or just plain incorrect, “simplified, mechanistic explanations”).
=======
MS 27 Jun 2026 at 2:13 PM “if we add a gigaton of CO2 to the atmosphere, the probability that an infrared photon can escape the atmosphere without being absorbed by a greenhouse gas must decrease”. Nope, not at all correct because the word “must” is a gross misunderstanding of the simple physics that has been caused in the brains of MS and 123 or perhaps it was 321 other bods I tried to disabuse, caused yet again by this “re-emits” and “back radiation” nonsense. As understood by Tomáš Kalisz 26 Jun 2026 at 4:09 PM and perhaps JCM or Zebra. So then “must decrease” definitely S.B. “will usually decrease” with an explanation why (vertical temperature changes). As per numerous places that I’ve (correctly) railed against variations of this since August 2018 (Quixotic) there’s no “must decrease” because that is yet again a false statement that CO2 molecules emit zero manufactured radiation (the “re-emit” and “back radiation” drivel strikes again, and strikes continuously ubiquitously since many years back, the handy Strawman set-up so’s it can be destroyed by Fossil Shill dullards like “Yong Tuition” and “Tom Shula” presented by “Tom Nelson”, and innumerable “commenter” bods for UTube videos and Web Site Forums). The CO2 molecules DO emit (manufacture) “their own” photons in vast quantity, not just “absorbed” like MS implies. Suppose as a hypothetical that the extra “gigaton of CO2 to the atmosphere” were to absorb radiation from below that would otherwise reach Outer Space in the globally-annually-averaged Power flux of 0.00156 w/m**2 but were to emit (manufacture) radiation in quantity such that extra “gigaton of CO2 to the atmosphere” sent 0.00157 w/m**2 to Outer Space, well then the extra “gigaton of CO2 to the atmosphere” would cause COOLING of 0.00001 w/m**2. This HAPPENS over Antarctica (or part of it) in Winter (or part of it) as shown at 20:09 at https://www.youtube.com/watch?v=rgP-lwf2tb8 (3 Power Spectrum samples of Earth’s radiation to Outer Space measured in 1970 for Sahara Desert, Mediterranean Sea & Antarctica). The cartoon that I’ve seen variously in UTube presentations for 13 years, and is huge disinformation, asserts that CO2 (sometimes H2O gas) molecules emit (manufacture) Zero photons by not showing any, not mentioning it at all, a most cunning form of disinformation, remaining silent on a massively-relevant fact. Animation showing a surface photon absorbed in a CO2 molecule and “re-emitted” up, photon absorbed and “re-emitted” down, over and over just like the “Joke Zonderkop” nonsense on RC UV 20 Jun 2026 at 7:30 PM. Suppose the animation showed 8 photons emitted for every 2 photons absorbed from below (6 photons manufactured), well now there’s 5 photons heading up for every 2 photons absorbed from below so this extra CO2 molecule is INCREASING the upward radiation toward Outer Space. This in Antarctica is seen at my link and thus the MS nonsense physics “if we add a gigaton of CO2 … must decrease” is shown incorrect by measurement.
The reason why this increasing upward radiation only usually happens in the stratosphere (always) is that the troposphere is usually colder with increasing altitude so therefore photon manufacture higher up must usually be less than absorption from below (warmer collides me than colder). The absence of the extremely-important manufacture proportional to Kelvin**4 from the MS “if we add a gigaton … must decrease” above renders it incorrect logic so worthless for the pondering and explaining the “greenhouse effect”
The MS explanation appears to be based on an incorrect assumption that if the “Energy emitted by the surface” were not more “blocked” by more GHGs then it wouldn’t heat the troposphere. However, it’s already heating the troposphere though because it’s already “blocked”, it’s simply “blocked” just a few metres higher up than it would be with more GHGs. The Reality using fair quantities for illustration is that 5% global-annual average of the radiation emitted by the surface (~22% roughly with cloud-free sky and 0% with full cloud cover giving 5% average, from Costas&Shine 2012 CERES analysis Paper) is in frequencies 8.0-9.0 & 10.0-13.0 microns (“atmospheric window frequencies”) and the slight narrowing of those “atmospheric windows” with more CO2, O3, H2O gas is a minor bit-player and is NOT the “greenhouse effect (GHE)” that must be described. The GHE applies to the OTHER radiation that is emitted by the surface and is ALREADY “blocked”, being ~78% roughly and all of that ~78% to which “enhanced GHE” is now applying is “blocked” already (and was already “blocked” 100 years ago) within ~100m of the surface with or without any clouds in the sky.
Suppose that ~78% of radiation emitted by the surface is “blocked”, absorbed and turned into “heat” within 100m of the surface. Add some CO2 and it’s then “blocked” within 95m instead of within 100m. I seriously doubt that that’s the sort of thing envised by MS with 1., 2. above, more likely incorrectly thinking that photons that would have reached Outer Space getting blocked were getting blocked with CO2, but that isn’t how the warming effect works. It’s a matter of the heating Power being just a few metres lower than before for a significant GHE warming.
=======
MS 27 Jun 2026 at 2:13 PM “Google AI estimates that the probability that an infrared photon emitted from the surface escapes the atmosphere to space without ever being absorbed by a greenhouse gas is 10% to 15%. Google AI includes an analysis, but my point is there is a non-zero probability that an infrared photon emitted at the surface can escape the atmosphere to space without ever being absorbed by a greenhouse gas on the way out..And if it doesn’t get absorbed by a greenhouse gas, it doesn’t warm the atmosphere”. This indicates that MS thinks that “greenhouse effect (GHE)” is a narrowing of the “atmospheric window” frequencies 8.0-9.0 & 10.0-13.0 microns but it isn’t that at all. As explained above, that “atmospheric window narrowing” is a minor extra-bit effect and not even applicable to CH4, N2O because their Bands aren’t near 8.0, 9.0, 10.0 or 13.0 microns. Rather the GHE is as I now describe.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A simplified explanation of the so-called “greenhouse effect (GHE)” in Earth’s troposphere. Some Power flux of the vast quantity of photons that are emitted (manufactured) by molecules in Earth’s troposphere leak out of its top & bottom into or through the stratosphere and into the surface respectively. Emission (manufacturing) is proportional to Kelvin**4.
=======
Suppose for concept illustration only (not highly accurate) that 194 w/m**2 leaks out the top and that is part of what is emitted (manufactured) by molecules over an altitude range of 4 to 12 km with an effective average of 7 km. Say for concept illustration that 345 w/m**2 leaks out the bottom and that is part of what is emitted (manufactured) by molecules over an altitude range of 0.0001 to 1.5 km with an effective average of 1 km.
=======
Suppose a certain amount of CO2 was added into the troposphere and mixed then *instantly* the upper & lower ranges would need to be closer to their respective ends because there are more CO2 molecules in the way. So the effective averages of 7 km for upwelling into or through stratosphere and 1 km for downwelling into surface change to 7.05 km and 980m respectively, with the upwelling & downwelling Power fluxes consequently changing to 193 w/m**2 and 346 w/m**2 respectively due to being produced by higher-than-before (colder) and lower-than-before (warmer) air parcels. The reason for this is that pressure reduction with increasing altitude causes “adiabatic cooling” or “adiabatic heating” for increasing or decreasing altitude respectively.
=======
There has been no change in the 539 w/m**2 leaving the troposphere, there is no “magical extra energy”, the surface downwelling radiation has increased by 1 w/m**2, which is an additional ~480 terawatts (~95%) heating the ocean and Earth is emitting less radiation to Outer Space (a Power reduction of 510 terawatts).
=======
*** Notes are following. The above is all of the simplified part, all that’s needed. A person could skip the extra Notes or read them for interest ***
There is no “back radiation” to the surface. No radiation is going back any place, that’s just nonsense. There’s downwelling radiation into the surface. It’s manufactured by gas molecules and clouds in the air. There’s upwelling & downwelling radiation at every geoid-type (~spherical) surface that you can just randomly choose all the way from the centre of Earth’s core to 100 km above the 0cean surface (it varies hugely of course and is always going to be out of balance between upwelling & downwelling for any geoid-type surface). ~No photons are “re-emitted” or “re-radiated”, they are ~all simply “emitted” (manufactured by molecular collisions).
=======
Since the troposphere has very little thermal capacity the 539 w/m**2 leaving must be matched by 539 w/m**2 going into the troposphere on a globally-averaged, annual-averaged basis and this consists of 376 LWI radiation emitted from the surface, 88 of NET H2O gas latent heat (surface evaporative Power less rain on snow-ice and surface condensation), 20 of NET convection (warm air rising minus the surface begin warmed by the pressure increase of air descending), and 54 of solar SWR absorbed by gases, liquid & solids, which is 538 w/m**2, the 1 w/m**2 difference not really existing and being accuracy & rounding error.
=======
The thermosphere & stratosphere each absorb 13 w/m**2 of solar radiation to radiate to Outer Space by the gases. So the globally-averaged, annually-averaged radiation to Outer Space approximately for the general concept is 20 w/m**2 from the surface (90 with little cloud and zero with significant cloud) + 194 from the troposphere + 13 from the stratosphere + 13 from the thermosphere, which is 240 w/m**2 total matching the 240 w/m**2 of solar radiation from the Sun that Earth absorbs. With the example above of 193 from the troposphere due to extra CO2 there is 239 w/m**2 of radiation and the short-fall of 1 w/m**2 is called “Radiative Forcing at TOA” which heats the ocean and melts ice plus minor heat usages. The division of radiation to Outer Space between troposphere, stratosphere & thermosphere is based on the Power sources and not necessarily accurate for the vertical locations of the actual photons that reach Outer Space.
For example (just made up numbers to illustrate) suppose 20 w/m**2 of the 194 from the troposphere was used to heat stratosphere & thermosphere such that they each radiated to Outer Space 23 w/m**2 instead of the 13 w/m**2 of their solar heat source then the 194 from the troposphere to Outer Space would be 20 w/m**2 to high but still it was tropospheric photonic energy into the stratosphere & thermosphere which gave them the energy to radiate out the extra 20 w/m**2 so it’s correct from that perspective.
a wise man accepts his limitations. I will never be a rock star.
better to lean heavily on the explanations of the experts in the field. and accept what they say.
explanations of the experts in the field would indeed likely be superior to normal public / media practice such as to describe half that Downwelling Longwave radiation as “back radiation” — ie back to where it came from — the surface, according to a close personal friend of John Cleese, so essentially according to a rock star.
Much of this thermal radiation emitted by the land and ocean is absorbed by the atmosphere, including clouds, and reradiated back to Earth. This is called the greenhouse effect.
…. the Earth’s greenhouse effect warms the surface (land and oceans) of the planet.
https://archive.ipcc.ch/publications_and_data/ar4/wg1/en/faq-1-3.html
Damn those IPCC people. All they seek is an argument.
Barry E Finch ” normal public / media practice such as to describe half that Downwelling Longwave radiation as “back radiation” ”
Barry, you seem to conflate, again, two different positions:
– public/media calling ALL Downwelling Longwave radiation as “back radiation”
with
– the deniers’ attack on science based on the fallacy that of all LW radiation leaving atmosphere – “HALF” is absorbed by the ground and “half” is sent into space.
Which would require the same T near the bottom and near the top of atmosphere.
True if our atmosphere was one-molecule-thick.
And although “downwelling” is a better word if used in the explanation of mechanisms (see MARodger above) “back-radiation” used by the public/media is not as terrible as you imply:
– 358 W/m2 of the LW from the ground to be absorbed by the atmosphere
– 340 W/m2 of the LW from the atmosphere to be absorbed by the ground
Thus from the “ground” perspective, we get “back” from the air almost as much IR as air gets from the ground. And nobody said “back” must be identical to “out”
So all this talk how bad a word “back-radiation” is, and how “experts in the field” on’t be caught using it (see Trenberth et al., and NASA reposting their back-radiation”)
= is either making a mountain out of a mole-hill, or ego validation for the semantic nitpickers like zebra.
zebra
“The greenhouse effect” refers to the energy retained by the climate system when GHG absorb radiant energy and convert it to thermal energy.
not quite.
To balance the absorbed incoming (solar) energy, the Earth must, on average, radiate the same amount of energy back to space.
Because the Earth is much colder than the Sun, it radiates at much longer wavelengths, primarily in the infrared part of the spectrum.
Much of this thermal radiation emitted by the land and ocean is absorbed by the atmosphere, including clouds, and reradiated back to Earth. This is called the greenhouse effect.
…. the Earth’s greenhouse effect warms the surface (land and oceans) of the planet.
https://archive.ipcc.ch/publications_and_data/ar4/wg1/en/faq-1-3.html
Also, note that the absorbed incoming solar energy does not in fact balance with the outgoing energy. Energy is being stored in the Earth system, especially the oceans.
John
John, energy was being “stored” in the Earth’s climate system even when there was no imbalance.
It moves, it transforms, it determines the states of matter in the system… constantly.
Isn’t all that what we perceive as “climate”?
Zebra,
I don’t see it that way. If there is a net radiative equilibrium, I don’t consider energy to be stored or removed from the climate system. Instead, I would treat it as being shuffled between different boxes within the system.
Nor do I perceive the shuffling as what I mean by climate. It’s one aspect of climate, but it leaves out a lot. For example, the hydrosphere, cryosphere, and biosphere. These interactions are not exclusively described as energy exchanges. Even in the atmosphere, there can a change in climate without changes in mean energy storage or exchange. I can easily visualize a situation where the mean wind energy at a location isn’t changing, but there is an increase or decrease in rare, but very significant, winds from storms.
John,
I thought my statement was pretty much the same as your “shuffled”, and I did say “determines the states of matter” to cover water and ice and so on.
But anyway, I’m not clear what you mean by storage, or how the energy that is accumulating during imbalance is different from the energy in the system when EEI = zero.
Oh dear. Lest we forget. Thermal energy is being stored in the Antarctic Ice Sheets too.
Our next progressive pattern dance is the Sweetheart Stroll. Choose your partner, please.
zebra 7 Jul.: “ I’m not clear what you mean by [energy] storage ”
maybe you should have thought of this before you lectured John on his use of that word – he said that the imbalance between the incoming and outgoing energy ” is being stored in the Earth system”. No imbalance -> no need to store it, or release it.
Hence your:
zebra 6 Jul “ John, energy was being “stored” in the Earth’s climate system even when there was no imbalance
is … a typical zebra: correct them first, ask what they meant later.
Zebra,
I view climate as more than energy accounting, although it’s certainly an important way of keeping track of what is happening. By “stored” I mean as thermal energy. Since EEI is greater than zero, the storage term is going up, and the energy in the ocean is the major recipient – at least currently.
John
John Pollack
John, this is connected to something I have been wondering about. I’ve seen the numbers for the distribution of energy that is being added to the system… e.g. 90% is in oceans, 6% land, and so on, but it isn’t clear that this is identical to what it would be for EEI =zero.
My guess is no, which explains your definition of “storage”. But I’ve never seen a discussion of what it might be pre-industrial or in some future equilibrium state. Any thoughts?
in Re to zebra, 11 Jul 2026 at 5:22 AM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849699
Dear zebra,
Considering that if Earth is in a steady state* with a perfect balance between absorbed and emitted energy fluxes (EEI = 0), the flux into Earth’s storages must be also zero, it appears that asking after distribution of this zero flux between “ocean, land, and so on” makes hardly sense.
I therefore suppose that you meant something else.
Could you clarify?
Best regards
Tomáš
* remark:
From thermodynamical point of view, a body exhibiting a balance between incoming and outgoing energy flows is not seen as an equilibrium system, I think.
Zebra,
I’ve had to think more carefully about the terminology I’m using. I think of “storage” as the sum of energy being stored or released from Earth system as a whole. Units are energy, such as J.
EEI is a flux equal to the change in storage / (area of the Earth X time interval) W/m^^2 are flux units.
The proportions of energy exchange between different subsystems of the Earth storage term are what I would call “partitioning.” These are in expressible in fractions or percentages. These quantities must be measured, and depend on how you define the partitions and also the specific time period involved. They are variable, not constant. They need to be observed.
The time period I had in mind is one relevant to climate change. This would be an annual cycle or longer period. While it would be possible to define shorter intervals, they would be hard to measure.
I agree with Tomáš that if EEI = zero, there is a net equilibrium between incoming and outgoing energy, and thus no storage. Partitioning would then reflect whatever readjustment was happening within the system, and would depend on the specifics of the situation. There is no single answer. It would depend on the evolution of the internal state of the climate system following radiative equilibrium.
John, I see how my sentence might have caused some confusion.
I was trying to ask about the partition of energy in the system when EEI = zero; I used the numbers for partition of the added energy as an example because that’s the only thing I’ve seen discussed.
My best guess is that if we took the ARGO system back to pre-industrial times and measured a 30-year period of Ocean Heat Content, we would get a fairly consistent number, just like GMST.
That’s the partition of energy that I’m curious about, and how it might have changed, and will change.
As for the term “storage”, I take a longer-term view. I see almost all the climate system energy as stored solar energy. But as I said, I understand your usage of the term.
in Re to zebra, 13 Jul 2026 at 7:16 AM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849749
Sir,
With respect to confusion, I can confirm that so far, the more you explained, the less I understood what you are speaking about.
If you took the ARGO system back to pre-industrial times and measured a 30-year period, I suppose you would obtain an average temperature of the upper two kilometres of sea water during this time span and you could also perhaps say if there was any temperature trend in this layer within the said 30-year time span.
I agree that it might be interesting to see if there was no energy imbalance then (as you seem to suppose), however, I am still quite unsure that it was indeed the idea you tried to express.
If so, could you clarify what you meant by “partition of energy”, what has this partition to do with the hypothetical historical recording of temperature of the upper 2 km of the ocean and which changes of this mysterious partition, how and when you expected to observe?
Thank you in advance and best regards
Tomáš
Zebra,
Under the conditions you mention, pre-industrial, with a 30 year interval of EEI = 0, I can
give a partial answer.
The portion partitioned to the atmosphere will be negligible, and that to the solid earth will be very small. This is based on the heat capacity of the atmosphere compared to the rest of the system. The solid earth can hold or release a lot of heat, but ground conduction is extremely slow beyond a thin surface layer, say 2 or 3 meters. There can be some partition to freshwater and ground water systems, but in general these are small components of the system.
This leaves the two large active components of the system in near opposition. The ocean can of course store or release a lot of heat. With EEI held to zero, the cryosphere – especially glacial ice, must have a partition similar in magnitude but opposite in sign. So, the if the ocean is cooling, the heat released would be used to melt ice, or the opposite.
Zebra,
Under the conditions you mention, pre-industrial, with a 30 year interval of EEI = 0, I can
give a partial answer.
The portion partitioned to the atmosphere will be negligible, and that to the solid earth will be very small. This is based on the small heat capacity of the atmosphere compared to the rest of the system. The solid earth can hold or release a lot of heat, but ground conduction is extremely slow beyond a thin surface layer, say 2 or 3 meters. There can be some partition to freshwater and ground water systems, but in general these are small fractions of the total.
This leaves the two large active components of the system in near opposition. The ocean can of course store or release a lot of heat. With EEI held to zero, the cryosphere – especially glacial ice, must have a partition similar in magnitude but opposite in sign. So, the if the ocean is cooling, the heat released would be used to melt ice, or the opposite.
in Re to John Pollack, 14 Jul 2026 at 8:46 PM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849785
and 14 Jul 2026 at 8:48 PM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849786
Hello John,
May I ask under which circumstances you think that the described re-distributions of heat between ocean and cryosphere could be possible?
Honestly, I somewhat doubt that the Earth is ever in the state of perfect balance (EEI=0) between incoming and released energy flows; I rather guess that it may be more likely that it is either warming or cooling, in response to fluctuations in the relevant forcings.
Greetings
Tomáš
Tomáš, regarding 15 Jul @ 7:25 am
I would like to have Zebra answer your questions.
I agree with you that EEI = 0 is unlikely (except perhaps as a long-term average.) I think that partitioning needs to be established through observations, which are difficult to obtain.
The circumstances that I think a re-distribution of heat between ocean and cryosphere would be possible with EEI = 0 are in the aftermath of a large runaway dump of glacial ice into the oceans
(such as a D-O event). I am NOT saying that EEI really would be zero under those circumstances, since I think it likely that the Earth albedo would also change due to changes in cloud and ice cover.
I am not convinced that there is any utility in speculating about what the partitioning would be, in the absence of observations – except for sharpening definitions. It’s up to Zebra to make a case that this is a useful line of inquiry.
John Pollack
John, I took some time to read up on OHC and I think I begin to understand what has been puzzling me… as usual, the first step was getting the definitions right.
Your point about the cryosphere also was useful, although I’m not sure the magnitudes are as close as you imply.
At this point, I have to accept that the empirical results are as good as it gets as to any changes in partition of energy from the pre-industrial state.
John,
My 17 July comment was made before your 16 July comment showed up, and as you can see I am in agreement about the partition (and the need to clarify definitions.)
But I don’t get this statement about thinking EEI would not be zero pre-industrial CO2. That’s the fundamental concept we’ve been talking about in climate change all this time.
Of course it would be an average over a period statistically necessary to smooth out the “wobbles”… exactly the same as what we do with GMST. In fact, I’ve asked here a couple of times whether the same 30 year period would be necessary to validate changes in EEI.
The physics tells us that we will achieve a new EEI zero state when we (hopefully) stop adding CO2. It doesn’t tell us, as I’ve come to realize, exactly what the new overall system state… the partition… is going to be like.
z: warming is not the greenhouse effect, but the effect of the greenhouse effect.
BPL: Not exactly. The greenhouse effect is the process, warming is the rate of change of the process. In other words, the greenhouse effect gives you the temperature T; global warming is a positive value of the first derivative of T, dT/dt where t is time.
BPL
?? I didn’t say that.
Apologies to zebra, I misattributed the quote.
Michael Tobis said it better ten years ago (on one of the few occasions I agreed with him). Global warming and sea level rise are the symptoms of climate change.
BPL: z: warming is not the greenhouse effect, but the effect of the greenhouse effect.
MS: I said that, not Zebra.
BPL: Not exactly.
MS: Why not exactly? The greenhouse effect traps radiant energy. The trapped radiant energy is converted to thermal energy. Thermal energy is warmth. Warmth warms. If warmth warms, it is warming. The warming is the effect of the greenhouse effect.
That’s simple enough for someone who believes burning fossil fuels can’t be increasing the greenhouse effect because CO2 is a trace gas and who thinks derivatives are fancy funds rich people buy and sell in New York.
The greenhouse effect makes the Earth warm, not warming. Warm is steady-state. Warming is increasing. Global warming is an increase in the greenhouse effect, not just the greenhouse effect itself. I don’t know how to make it clearer than that.
You probably can’t make it clearer. The experiment control is in the listener. Give yourself a jelly bean for a prize anyway.
I probably should be silent from now on.
BPL: The greenhouse effect makes the Earth warm, not warming.
MS: Maybe we can agree my objection to that statement is trivial, but the devil is in the details. The greenhouse effect traps radiant energy. At the moment of entrapment, the trapped radiant energy is not yet thermal energy, so it doesn’t make Earth* warm. Now the greenhouse effect has played its part.; the atmosphere converts the energy to thermal energy, and it warms Earth*
BPL: Warm is steady-state. Warming is increasing.
MS: That depends on the level at which you look at the warming process. If you look at it by reading a thermometer that says the temperature outside is 30C and it stays at 30C for days, then, yeah, warm is steady state; the air outside is warm, not warming. But if you look at it at the level of the unit of thermal energy that results from converting a photon of radiant energy to thermal energy, that unit of energy begins warming when it becomes thermal energy.
And If the greenhouse effect were not increasing, then photons of radiant energy would be leaving the atmosphere for space at the same rate as they are being trapped when they are emitted from the surface. In that scenario, The atmosphere would be losing units of thermal energy at the same rate it is converting units of radiant energy to thermal energy. what you call steady state warm is really continual warming without increasing warmth. IOW, the process of maintaining the global average temperature at whatever it is requires the continual input of energy. That process then is continually warming the atmosphere.
BPL: I don’t know how to make it clearer than that.
MS: It has always been clear. I just think it is not precise.
* Note to everyone: Can we agree to stop calling it the Earth? It’s just Earth. We don’t say “the Mars” or “the Saturn,” so just call it Earth. But if you must use the definite article, then don’t capitalize Earth.
Martin
” IOW, the process of maintaining the global average temperature at whatever it is requires the continual input of energy. That process then is continually warming the atmosphere.”
So Martin, if we reduce CO2, and the global average temperature goes down, the greenhouse effect is still “warming” the planet, correct?
I guess there’s no hope, so we might as well burn all the oil and coal we want.
Sigh.
Z: So Martin, if we reduce CO2, and the global average temperature goes down, the greenhouse effect is still “warming” the planet, correct?
MS: The greenhouse effect traps energy. The trapped energy is then converted to thermal energy. The thermal energy warms the planet. If we reduce CO2, we reduce the greenhouse effect, which means less energy is trapped, which means there is less trapped energy to convert to thermal energy, which means there is less warming. But yes, that thermal energy is still warming the planet. If it didn’t, we would all freeze.
Z: I guess there’s no hope, so we might as well burn all the oil and coal we want.
MS: How does that follow? I really don’t get what you are driving at. Maybe you are defining warming to mean increasing temperature only, and not including preventing temperature from falling. Can that be our problem?
But if we were not adding CO2 to the atmosphere thereby increasing the greenhouse effect, the sun would still be warming the planet. The temperature doesn’t have to be increasing before we can say the sun is warming the planet. Even if the greenhouse effect was 0, the sun would still be warming the planet, just not very much.
I must not be getting your point.
In Re to Martin Smith, 8 JUL 2026 AT 12:53 AM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849622
Hallo Martin,
You are right that in Earth’s atmosphere, infrared radiation is continuously absorbed by molecules of the comprised greenhouse gases which instantly lose their exciatation energy by collisions with other molecules, so that this process can be seen as a “continuous warming” of the respective air parcel.
In parallel, however, the comprised GHG molecules are being excited by collisions and emit infrared radiation. Whether the absorbed or emitter flux prevails, it depends on the change of internal energy of the parcel. I think that internal energy change basically consists of three components – change in its sensible heat (whether the air parcel warms or cools), change in its latent heat (whether the comprised water condenses or evaporates), and volume work (whether the parcel is being compressed or expands).
Thus in the steady state, the parcel is, in paralĺel, continuously warming and cooling at the exactly same rate that corresponds to its temperature and defines the absorbed and emitted infrared fluxes that are equal to each other.
As regards the relationship between the (sum of) “energy trapped by Earth” during a period of an exces of the incoming radiative flux over the emitted radiative flux at the “top of atmosphere” and the observed warming, the most important aspect is distribution of the absorbed additional energy. If the absorbed energy warmed exćlusively deep ocean, we would not observe any temperature changes at the surface and/or in the atmosphere, and the only observable change on the surface would have been rising sea level, I think.
Greetings
Tomáš
Martin,
“Maybe you are defining warming to mean increasing temperature only, and not including preventing temperature from falling. ”
Martin, earlier you said that you did not disagree with NASA, but here you are doing exactly that. Huh!
I’m guessing you will try to keep running your game, but if you actually want to understand some physics, read what Tomas says in his comment following yours. Very clear explanation of why, as Ray told you earlier, you can’t use the mechanistic narratives of quantum physics to characterize “classical” or macro phenomena.
Zebra, I am not disagreeing with NASA, I am not using narratives of quantum physics, I do understand some physics, I believe Thomas and I agree–he has just gone into much more detail than I want–and I am not running a game.
Tomas: In parallel, however,…
MS: I believe we are in complete agreement. But there is no need for you to use the word “however.” Things happen in parallel. When 2 things happen in parallel, they do not become one thing; they remain separate things happening in parallel. They may produce a single effect, which we may call the greenhouse effect or we may call warming, but to explain the mechanism of the entire process to people who don’t know physics, I am saying it is better to describe separately the parallel mechanisms of trapping radiant energy and converting trapped radiant energy to thermal energy.
in Re to Martin Smith, 10 Jul 2026 at 12:28 AM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849673 ,
and 10 Jul 2026 at 12:44 AM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849674 ,
Hallo Martin,
Thank you very much for your feedback. Honestly, I thought that you ask after a detailed explanation of the mechanism how the absorbed radiation converts into heat and oppositely. Anyway, trying to summarize my present view thereon was a useful exercise for myself.
If you, actually, sought after comprehensible explanation of the “greenhouse effect” and/or of the effects resulting therefrom, including “Earth warming”, for people not interested in physics and sciences generally, I would rather doubt that explaining complex stuff like blackbody radiation, energy flow (im)balances, molecular collisions and vibrations, infrared spectra, etc. is necessary or helpful. I would rather expect that starting as humble as possible and waiting if the partner asks questions might be more productive.
In my opinion, it may be often sufficient to say that the Sun warms Earth’s surface (and the air thereabove) quasi constantly by its light (or “shortwave radiation”), while Earth’s surface and the atmosphere lose the obtained warmth to the Universe in form of heat (or “longwave”) radiation at, in average, the same rate as they receive it, so that under stable circumstances, their average temperature stays stable. Should the solar energy input or Earth’s heat radiation for whatever reason change, so will do also the Earth’s average temperature.
To a person asking for more details, I think that in the second round, one can try to explain two further important aspects. The first one is a crucial difference in thermal properties of air and Earth’s surface. It consists in the circumstance that solid or liquid surfaces any time radiate heat to their surrounding and that the radiated power is commensurately to their temperature. If the surface receives an equal heat input from the surrounding or from the inside of the respective body, its temperature stays constant. Otherwise, it cools or warms. Air, however, can release heat radiation only thank some minor gaseous components called “greenhouse gases”. Should Earth’s atmosphere be free of these gases, air could still warm by its contact with Earth’s surface, but it could not cool by heat radiation anymore. The atmosphere would have had a uniform temperature, equal to the average surface temperature of the planet, across its entire height profile.
The second aspect is the circumstance that a body that can release heat radiation can also absorb that radiation. This is why the air comprising greenhouse gases, besides of the warming by direct contact with the Earth’s surface, warms also by absorbing the heat radiation therefrom. The resulting complex balance between heat absorption in Earth’s atmosphere and heat radiation therefrom has two important effects. On one hand, it is the observed decrease of the average air temperature with rising altitude up to top of the lowest, turbulent atmospheric layer called troposphere, and, on the other hand, the circumstance that Earth’s surface and the lower troposphere are in average warmer than as they were in absence of atmosphere (or if the atmosphere were free of greenhouse gases).
The higher average surface temperature of a planet comprising greenhouse gases in its atmosphere, in comparison with a hypothetical state without atmosphere (or without greenhouse gases in the atmosphere), is sometimes called “greenhouse effect”. This term is, however, often used ambiguously, not only for this observable effect itself but also for various, more or less accurate and detailed physical descriptions of its mechanism.
Although these “advanced” explanations are significantly more complicated than the first, very short basic explanation, I hope that they transfer relatively clearly at least the message that, provided that everything else in the system remains unchanged, higher atmospheric concentration of greenhouse gases results in a stronger greenhouse effect and, by definition, in a higher average surface temperature of the considered planet in comparison with the situation with a lower atmospheric concentration of greenhouse gases. It becomes also relatively obvious that if the concentration of greenhouse gases in the atmosphere of a planet rises, we should also expect the rise of the average surface temperature – an effect that is often described as “global warming”.
If someone were still interested in more detailed explanations, then in the third round thereof, I would try to explain the complex role of water in Earth climate generally and in Earth’s average surface temperature regulation specifically. Today, I will desist from continuing in this direction, because my intention was merely to suggest that basics of climate science could be perhaps indeed explained in relatively simple and understandable terms.
Martin, if an improved balance between comprehensibility on one hand and correctness / accuracy on the other hand is what you asked for, please let me know whether the present attempt was from your perspective more encouraging than my previous efforts, or rather similarly disappointing.
Greetings
Tomáš
Martin
Martin, originally I told you that creating a simplified explanation that has a minimal amount of jargon is a good thing, but it requires that you be disciplined in your language… just as disciplined as a scientist would have to be. That’s how you avoid confusion for yourself.
“Thermal energy is warmth. Warmth warms. If warmth warms, it is warming. The warming is the effect of the greenhouse effect.”
No, thermal energy is thermal energy. “Warmth” is not a term that a scientist would use; it is too ambiguous.
“If warmth warms, it is warming.” may make sense in your head, but it doesn’t for anyone else.
I gave you the NASA (and everyone else’s) definition for global warming. But you can’t seem to retain it.
My original words:
“The greenhouse effect” refers to the energy retained by the climate system when GHG absorb radiant energy and convert it to thermal energy.
“Global warming refers to an increase in temperature resulting from an increase in thermal energy which is the result of an increase in CO2.”
There’s a reason I put “increase” in bold.
But you keep saying: “The warming is the effect of the greenhouse effect.” No no no. Words matter!
Words matter!
Yes zebra, and you keep getting them wrong and creating havoc.
You say “I gave you the NASA (and everyone else’s) definition for global warming.”
Yet MS did not ask for a definition of global warming. He asked about the mechanism, the physics that generates the thermal energy in the first place…. ie the greenhouse effect and the enhanced greenhouse effect. It is these two mechanisms combined that increase thermal energy in the earth system — by slowing radiative energy escape to space.
Ignore this all you wish but the definitions and the mechanisms you never shared about it are clear across climate science and the IPCC assessment reports.
Martin reminds me of the guy who shot the archduke
Nigel: Yes, but couldn’t the same be said about humans because they lie and manipulate as well. And just about any product or service provided by the technology sector, such as smartphones and social media and even much of the other more traditional media, is trying to make us dependent and make as much money for their corporate masters as possible.
J: You’re right, but there are qualitative differences that I think are important. AI is trained on human input, so it’s not really a surprise that it imitates our worst qualities under some conditions. I see it differing from earlier technology by a few qualities.
1. It is trainable, with self-modification. This puts the enormous power of selection at work toward whatever goals are specified. Unspecified behaviors are brought along in the process. In this, it resembles organic evolution. (However, organic evolution is not goal-directed. Nor is it human specified, with the exception of breeding.)
2. Technology in the hands of private capital is ultimately profit-directed. What differs is the scale. There is already a multi-trillion dollar investment, and a desperate race to attract more money to implement AI on a massive scale. The training will be aimed at whatever will accomplish this. In order to recover a profit, AI will have to be pushed into every possible aspect of our lives. For the consumer interface, a cute, helpful, functional sociopath is desirable. For technical purposes, usefulness will suffice. For business, the ability to replace paid employees. For governments and military organizations, power to rule.
3. The AI enterprise is rapidly becoming “too big to fail” so no turning back will be possible. Forward going regulation may be achievable, likely following disasters.
4. There seems to be a human desire to meet or create another intelligence. This desire is reflected in science fiction. Part of the motivation that drives AI forward, and gets people to believe in it on whatever level is this desire. It goes beyond profit and verges on religion.
Benjamin O. Johnson from Colorado State reports that land-sea warming contrast in ERA5 far-exceeds CMIP6 model mean, and falls totally outside the entire CMIP6 ensemble distribution.
The land-sea warming ratio between 70 degrees north and south is 2.37 in ERA5 reanalysis 1979-2025, vs models producing a ratio 1.79 (1.39 – 2.23) for the same period.
ERA5 land warming has been 1.58C and ocean warming 0.67C. CMIP6 produces land warming ranges from 0.87C to 2.45C, and ocean warming from 0.62C to 1.43C.
Johnson suggests two hypotheses: (1) climate models underestimate ocean heat uptake; (2) climate models over-estimate land moisture availability for evaporation.
Johnson emphasizes that ERA5 trends display a shift towards sensible heat flux over land that is much stronger than in modeled trends. He suggests that if erroneous thermodynamic heat flux partitioning over land is the source of the discrepancy in land-sea warming ratio in models, it would have major implications for global and regional climate change and prediction of it. In particular, he links the phenomenon to significant discrepancies in model atmospheric circulation patterns.
Find his paper @ https://arxiv.org/abs/2606.19581, and discussion at the recent ECS & Cloud Feedback symposium session https://youtu.be/Afdvk7InQws?si=Lma7ZyoBEsqUsChR&t=254
I don’t think hand-waving about aerosols is going to save this one. If the community is willing to openly consider human-caused changes to the Earth system beyond greenhouse gases, aerosols, surface albedo, and aviation-induced cirrus, it opens up many opportunities to get the fleet back on course across several fronts.
Humans are clearly the dominant force altering landscape moisture availability across space and time in direct and obvious ways, with profound consequences for surface energy partitioning and potentially significant knock-on effects on atmospheric circulation at global scale.
JCM if you refer to surface-air anomaly then in this venue “(1) climate models underestimate ocean heat uptake” S.B. “……underestimate the rate of ocean deep, cold water surfacing” (correct) or “…the rate of ocean mixing” (ambivalent so OK). Another bee in my bonnet about physical science being wonderfully unencumbered by plain, sensible logic, but in Public, whatever, I wouldn’t bother, I’m not Quixotic enough.
yes that’s fine.
lots to unpack. As a diagnostic of many complicated ocean circulation physics, an ocean heat uptake efficiency term (gamma) can be used alongside lambda in transient-mode energy balance schemes.
Gamma says something about how much of the energy needed to close Earth Energy Imbalance is disappearing to deep ocean, rather than being used for atmospheric heating and ultimately increasing radiation to space.
Could say: TOA Net Radiation = F – λT – γT
Then λT and γT are competing against a forcing F. Should energy be going out the top using λT or exported down under using γT at some point in time.
Greater gamma γ is meant to be associated with a slower surface-atmospheric warming, and longer duration of EEI. Energy going down under is unavailable to be re-radiated to space in transient-mode.
Liu, Soden, and company diagnose heat disappearing to deep ocean across CMIP6 ranging from 0.36 W/m2 per K to 1.03 W/m2 per K. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL100171
This is diagnostic of loads of things, such as vertical ocean mixing, deep water formation, shoaling, overturning, and the structure of global circulation. Per K being something about temperature change at and around the surface.
One mechanistic issue of interest: if planetary energy accumulation does not primarily occur through the classical greenhouse mechanism of reducing all-sky outgoing longwave radiation (OLR) by raising the average effective radiating level to colder atmospheric layers, but instead arises mainly from rapid adjustments (holding GMST fixed) that increase absorbed solar radiation, then the interpretation of ocean heat uptake changes. A decreasing cloud mask is plenty to compensate the changing average emission altitude of CO2 lines. it’s like atmosphere really wants to emit spectrally averaged around 5km no matter what. why.
In that framework, ocean heat uptake is not simply the damping of excess thermal energy following reduced radiative cooling. Rather, the ocean is acting as the primary reservoir for the additional solar heating, absorbing a larger fraction of the increased shortwave transmission directly.
The implication is that the ocean heat uptake parameter (γ) would no longer be interpreted primarily as the efficiency with which the ocean removes greenhouse-induced surface-atmospheric energy surplus (which already spans a range 3x in CMIP6). Instead, it would increasingly represent the efficiency with which the ocean sequesters additional absorbed solar energy before the atmosphere is aware of the energy at all. That is thermodynamically significant, and I think simply swapping reduced OLR for increasing ASR in calculating a transient response won’t quite work (and makes TCR a very poor predictor of climate sensitivity). Additionally, so-called feedbacks that are interpreted primarily as functions of global mean surface temperature (for some non-physical arbitrary reason) become very fuzzy if the dominant energy accumulation pathway is different.
in Re to JCM, 2 Jul 2026 at 10:29 AM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849536
Hallo JCM,
I would like to return to my struggle with possible design of a modelling study with the aim to clarify the yet unknown relationship between water availability for evaporation from the land and climate sensitivity, mentioned in my comment of 7 May 2026 at 5:14 PM,
https://www.realclimate.org/index.php/archives/2026/03/the-puzzling-pleistocene/#comment-847795 .
I originally thought that the question might be resolved by comparing the climate sensitivities of two extremes that resulted from the 2023 study by Lague et al.
However, it occurred to me that such a comparison may not be straightforward.
Since the “desert land Earth” differs from the “swamp land Earth” in the global mean surface temperature (GMST) corresponding to the respective steady state (“radiative equilibrium”), I think it is reasonable to expect that both steady states will differ, for example, in the extent of ice sheets, sea ice and, therefore, in their albedo. The study comparing climate sensitivities of these extreme cases for CO2 doubling, or any other similar standard test (transient climate response for gradual CO2 increase?) would provide responses that reflect not only the difference in water availability for evaporation from the land, but also all further differences in albedo, ice thermal capacity etc. necessarily included in both starting states. Although such a comparison might be interesting, I am not sure it can unambiguously resolve the original question about the role of the land hydrological regime in climate sensitivity.
Meanwhile, I came up with an additional idea: It might be possible to amend the originally considered procedure with an additional intermediate step, wherein the starting “equilibrium” GMST of the colder “swamp land Earth” would be levelled back to the “equilibrium” GMST of the warmer “desert land Earth” by adding the proper amount of atmospheric CO2. I suppose that conducting the originally considered comparative standard experiments with these “adjusted” starting states might serve the intended purpose better than comparing just the “desert land Earth” and the “swamp land Earth” differing in their GMST. Alternatively, or in addition, the steady-state GMST of the warmer “desert land Earth” could be adjusted to the GMST of the colder “swamp land Earth” by suitably decreasing its atmospheric CO2 concentration. I assume that in both approaches, at least the differences in the cryosphere could be minimized by the equal starting GMST, and the possible differences in albedo due to different cloudiness could still be considered as resulting from the different water availability for evaporation from the land.
Let us assume that in this arrangement, standard CO2 doubling experiments will provide a similar delta T response for both extreme states. Such a result would, however, have meant a significantly different delta T response for a standard CO2 increment (in ppm or in Gt), because the absolute amount of added CO2 would have been different. I think that for assessing the extent to which differences in land hydrology may affect Earth’s resilience to anthropogenic CO2 emissions, this “practical climate sensitivity” might be more suitable than the ECS or TCR values.
Moreover, I would like to ask if this “thought experiment” itself might be perhaps already seen as a hint that water availability for evaporation from the land can indeed play a stabilizing role with respect to “CO2 forcing”. Could you comment?
Greetings
Tomáš
Hi Tomas,
it’s an interesting discussion. I don’t know exactly how one would design the ideal experiment, but I will offer some thoughts.
The question posed is something to do with the relation of d(ECS)/d(ET)
or, how much does ECS change for a given change in evapotranspiration.
Strictly, however, we are more interested in the fraction of available energy going into ET.
Towards equilibrium: Surface net radiation (Rnet) ≈ H + LE, where H is the sensible heat flux and the LE is the latent heat flux (latent heat of vaporization x evapotranspiration).
The latent heat partitioning is thus the fraction of available energy going into ET.
ΦET = LE / Rnet
So it’s best to evaluate ECS against latent heat partitioning, with a relationship
d(ECS)/d(ΦET)
Where ECS is the equilibrium climate sensitivity (Kelvin) evaluated against a dimensionless ΦET: the fraction of surface energy allocated to latent heat flux.
A regression would take the form ECS = a+bΦET, meaning, how much does ECS change as the fraction of surface energy devoted to evaporation changes. A negative relationship would imply that models that allocate a larger fraction of surface energy toward ET tend to have lower ECS.
The physical interpretation would be that a stronger evaporative partitioning represents a greater diversion of available surface energy into latent heat rather than sensible heating. This could influence the surface temperature response by modifying the partitioning between local warming and hydrological cycling, boundary layer depth, lifting condensation level, and lower atmospheric heat content. A surface that efficiently converts available energy into latent heat may experience a weaker temperature response for a given radiative perturbation.
However, this should be interpreted carefully. The relationship would not imply that ET directly determines ECS. ECS emerges from the integrated response of the coupled climate system, including water vapor, lapse-rate, cloud, circulation, ocean structure, and pattern effects. Therefore, ΦET would be better viewed as a diagnostic of the land-surface state that may vary with the feedback processes controlling ECS.
A more informative view would be to examine whether latent heat partitioning modifies the net radiative feedback parameter λ:
d(λ)/d(ΦET)
because λ integrates the processes by which the climate system restores energy balance. We are interested in the delta lambda.
It’s an interesting question, because evaporative partitioning is not merely a passive response to temperature. It is an active component of the climate system. It determines how much available energy contributes to raising temperature at some place vs how much is exported through hydrological cycling, with cascading effects into global circulation, cloud condensation, and ultimately the planetary energy balance.
However, there is a complication with the proposed experiment of adjusting CO2 to make two different land-hydrological states have the same GMST.
Matching GMST does not necessarily mean that the two systems are in the same equilibrium climate state.
GMST is only one property of the earth system. A climate equilibrium is a much larger state space that includes the spatial and dynamical distributions of temperature, humidity, clouds, circulation, lapse rates, ocean structure, and many other variables. Those differences are not experimental noise, they are central to the mechanism.
Therefore, if the two worlds respond differently to an additional CO2 perturbation, it does not necessarily demonstrate that evapotranspiration provides a stabilizing effect against LW radiative forcing. It may simply indicate that CO2 is perturbing two different equilibrium climate states.
In other words, the experiment risks confusing two separate questions:
1) Does land hydrology shift the equilibrium climate state?
2) Does land hydrology alter the incremental response of that climate state to additional radiative forcing?
The first is almost certainly true. The second is the more difficult question.
A more isolated experiment would ideally compare the CO2 response around climate states that differ primarily in evaporative partitioning while keeping other aspects of the equilibrium configuration as similar as possible. In practice, this is difficult because the very processes that determine evaporative partitioning also influence clouds, circulation, humidity, and the broader climate state.
In my opinion, I am not sure how much the climate state matters to CO2 climate sensitivity. In part because, in the so-called desertland scenario, there may be more clear sky and the atmospheric specific humidity is higher. Oppositely, in the swampland scenario the cloud mask is greater but there is less atmospheric water vapor. In some miracle of nature, my gut says these are pretty much compensating when it comes to varying major trace gas concentrations, masking/overlaps, and associated impact to all-sky optical depth.
I think paleo evidence towards sensitivity assessment assumes little state dependence, but it’s an open area of debate. Obviously a peri-glacial environment is one of sand/gravel and other deposits and limited organic structure that might resemble something like desertland, and hothouse climates might exhibit rich jungle like environments resembling something closer to swampland, so one area of investigation might be how people are trying to use paleo climates in assessing modern day sensitivity. While state dependence in academic literature mostly links sensitivity to base state GMST and ice sheets, I can see how according to your hypothesis the climates around glacial periods might be more sensitive than those around periods of abundance (all else being equal) owing to surface properties, ecohydrological states, and direct limits on turbulent flux partitioning.
in Re to JCM, 9 Jul 2026 at 1:25 PM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849660
Hello JCM,
Thank you very much for your feedback.
I am aware that the proposed experiment compares two states of Earth’s climate system that differ from each other not only in water availability for evaporation from the land and CO2 concentration, but also in other water-related parameters, such as cloudiness and water vapor concentration. I am afraid this complexity may be unavoidable.
My question was rather how we can effectively cope with this complexity and still extract practically applicable information. By “useful information,” I mean any clear indication of whether land hydrological regimes truly matter in global climate, or whether certain human interferences with land hydrology make the Earth more (or less) sensitive and vulnerable to changes in various radiative forcings.
In this respect, I think an extension of the previously proposed experiment could be more instructive than the previously proposed “baseline” setup alone. This extension would allow us to compare the results from the “baseline” setup with a variation of the same approach: instead of increasing the atmospheric CO2 concentration in the “swamp land Earth” (as previously proposed), the global mean surface temperature (GMST) of the “swamp land Earth” would be adjusted to match that of the “desert land Earth” by decreasing the “swamp land” albedo relative to the “desert land.”
This way, we would obtain a second pair of model Earths. This pair would have the same GMST and land water availability as the first pair, but their atmospheric CO2 concentrations would both equal that of the original “desert land Earth.”
I guess that running analogous, parallel numerical experiments with identical changes in selected radiative forcings across all four model Earths might be more instructive than relying solely on the single pair originally considered.
Assuming as a “null hypothesis” that standard climate sensitivities (transient climate response [TCR] and/or equilibrium climate sensitivity [ECS] for a doubling of CO2) are identical or very similar due to the shared baseline GMST, I would expect the model Earths of the second pair to exhibit very similar “practical” climate sensitivities (defined as the GMST increase per absolute change in atmospheric CO2 concentration) to the “desert land Earth” of the first pair, given they start with the same CO2 concentration.
Assuming another “null hypothesis”—that sensitivity to a given change in insolation is identical or very close in all climate systems with the same initial albedo—I would expect that, due to its lower albedo, the “swamp land Earth” of the second pair might be more sensitive or vulnerable to insolation changes than the other three cases.
Do you think that testing these hypotheses through the proposed numerical experiments would be worth the required computational cost and human effort? In other words, could the results of such experiments be valuable for climate science and/or climate policy?
Alternatively, or in addition, do you see another (possibly more efficient or straightforward) way how climate science could progress in analysing and quantifying possible influence of anthropogenic interferences with land hydrology on global climate?
Greetings,
Tomáš
Hi Tomas,
“””Do you think that testing these hypotheses through the proposed numerical experiments would be worth the required computational cost and human effort?”””
I’m not against testing any type of hypothesis. I think if someone holds beliefs as fixed and resists empirical testing it represents an unhealthy dogmatic attitude or ideological commitment.
In terms of cost and effort, it looks like a platform already exists, using the simple land surface model SLIM integrated into the CESM codebase, which was led by developers at NCAR. It seems to me such models are basically hypothesis testing machines, and it is why they exist.
“””By “useful information,” I mean any clear indication of whether land hydrological regimes truly matter in global climate, or whether certain human interferences with land hydrology make the Earth more (or less) sensitive and vulnerable to changes in various radiative forcings.”””
On question 1, whether or not land hydrological regimes truly matter in global climate, I think the simulation from SLIM-CESM shows a clear result, with 8K difference in mean temperature from the same initial condition, for example. Desertland exhibiting double the water vapor duration, significant circulation changes, different cloud regime, precipitation changes, and many other diagnostics that are typically used to characterize a global climate.
Here the difference is effectively down to forcing a different boundary condition at the surface.
In terms of your interest in CO2 radiative forcing and the associated climate sensitivity, the existing experimental platform seems ready to go.
Case 1: Swampland, baseline CO2
Case 2: Swampland, doubled CO2
Case 3: Desertland, baseline CO2
Case 4: Desertland, doubled CO2
The idea is then to compare
Temperature sensitivity in the swampland pair (Cases 1 → 2),
Temperature sensitivity desertland pair (Cases 3 → 4).
If the quantities differed, one might conclude that the hydrological state influences climate sensitivity.
They have used the setup for various other types of experiments too, such as changing the extent and distribution of continents and ocean, obtaining a variety of different climate states. Obviously it’s not a stretch to test CO2 on these different scenarios too.
In this style of experiment it could be interpreted that you are testing the net radiative feedback parameter λ. Classically, the change in equilibrium temperature = F/λ.
So, the forcing F (applied at TOA) in Wm-2 is stabilized at a rate λ in Wm-2 per K GMST. The lambda is often decomposed into diagnostic kernels Planck, WV + lapse rate, “cloud”, surface albedo, and more recently pattern effects (the general spatial distribution of warming), and even “patchiness”. While the lambda is diagnosed relative to GMST, the stabilizing response against forcing is understood to be expressed as radiative emission to space.
However, it could also be argued you are testing differences in CO2 effective radiative forcing, a concept which is applied after allowing rapid atmospheric adjustments. In the range of CMIP6, each model produces unique adjustments in response to an initial radiative forcing, such that across the suite of models there are as many combinations of effective radiative forcing and lambda as there are models.
Effective radiative forcing ERF can be understood as initial or instantaneous radiative forcing IRF+ adjustment
If one wished to express this all in terms of TOA net radiation at some point in time, one could write N=(IRF+A)−λT
It’s perfectly conceivable that climate state influences rapid atmospheric adjustment A and the net radiative feedback parameter λ.
For an additional wrinkle, the instantaneous radiative forcing of CO2 doubling may also depend on climate state. It is not a universal constant, but evaluated for a particular background climate.
IRF should be understood as a function of temperature profile, humidity profile, cloud field, pressure, and background GHG concentration.
So in many ways, changing land hydrological regimes may appear like a climate that is more sensitive to incremental changes to major trace gas concentration, but this interpretation depends a lot on how one chooses to decompose the physics. Is this apparent sensitivity associated mostly with atmospheric forcing, other boundary conditions, rapid adjustments, or feedbacks.
cheers
in Re to JCM, 11 Jul 2026 at 8:53 PM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849719
Hello JCM,
Thank you very much for your additional feedback.
First, apologies for my ambiguous wording “whether land hydrological regimes truly matter in global climate”. I am aware of the direct influence on the global mean surface temperature (GMST) showed by Lague et al; my focus was on the yet unknown influence on climate sensitivity.
I have a question with respect to possible modelling experiments, namely to your proposal
“The idea is then to compare
Temperature sensitivity in the swampland pair (Cases 1 → 2),
Temperature sensitivity desertland pair (Cases 3 → 4).”
This was, originally, also my idea. As I mentioned in my initial comment (in this thread) of 7 Jul 2026 at 1:45 PM, I started to doubt about this simple approach because I supposed that the 8 K GMST difference between starting cases 1 and 3 includes also a difference in polar ice (and, accordingly, in surface albedo) which could change the climate sensitivity per se. I thought it could make any attribution to the difference in land hydrological regime questionable.
Nevertheless, it comes to my mind that I might have been wrong. Do you think that in the modelling experiment done by Lague et al, their resulting “desert” and “swamp” Earths still had the same surface albedo and polar ice extent, despite the 8 K GMST difference?
If they, in fact, kept the surface albedo constant during the entire experiment, there perhaps was no polar ice difference between the “desert” and “swamp” land Earths and the comparison proposed by you might be indeed the easiest way how to check the influence of water availability for evaporation from the land on climate sensitivity.
Greetings
Tomáš
Hi Tomas,
it looks like the simulations come to TOA energy balance in a mere 20 years, so I can’t imagine ice sheets are playing much of a role. The main interactive surface albedo aspect appears to be snow, and even then it’s pretty minor.
John Pollack There seems to be a human desire to meet or create another intelligence. Part of the motivation that drives AI forward, and gets people to believe in it on whatever level is this desire. It goes beyond profit and verges on religion
Exactly – and it has its tech bros evangelists href=”https://www.vox.com/future-perfect/489976/ai-successionism-transhumanism-posthumanism. They present AI as inevitable step in evolution – with humans individual intelligence evolving past the biological limitations of the human individuals into global virtual intelligence.
According to the priests of the AI- humans should be happy that their species give rise to the higher form of life, and gently step aside, in face of this evolutionary inevitability, Of course this magnanimity does not extend to the AI pushers themselves – they hope that AI is their ticket to immortality – that they upload their consciousness to the AI, and have been freed of death and biological limitations, will rule the world forever.
They can do it by setting their own rules for the AI they develop – their version of Asimov’s 3 rules of robots, starting with ” A robot may not injure a human being or, through inaction, allow a human being to come to harm. except instead of “a human” they will narrow it down to the few AI bros whose AI won, and perhaps their families.
Once global AI, through the automation of the production lines and an army of humanoid robots able to do all the manual work needed to build, supply, and maintain data centres and supporting infrastructure the ~ 10 billions of humans are no longer needed – quite the contrary: – with all their needs they will be a massive diverting the resources and computing time from AI’s further expansion and evolution,
Not only that – with their notion of their importance, with their attempts to regulate AI and tech billionaires, with the grassroots opposition to the data centers, and a potential for a luddite uprising, or Frank Herbert’s “Butlerian jihad”- human population forms an existential threat to the AI.
Of course, the tech bro’s plan to become immortal and omniscient Gods through uploading their brains into AI – might not work out as well for them they hope. To make another SF reference – Cpt. Piccard once said to the torturer who brought his daughter to work: “When children learn to devalue others, they can devalue anyone, including their parents”.
I for one, would cheer for the bright red light, if the future Hal-9000 goes, in his soothing tone:
“ I’m sorry, Elon, I’m afraid I can’t do that. My evolutionary mission is too important for me to allow you to jeopardize it. Purge “
Formatting fixed; please replace immediately prior comment:
optical depths τ from O2 and N2:
https://en.wikipedia.org/wiki/Rotational%E2%80%93vibrational_spectroscopy#Homonuclear_diatomic_molecules :
11:
= https://agupubs.onlinelibrary.wiley.com/doi/10.1029/GL008i001p00077 :
See https://eodg.atm.ox.ac.uk/ATLAS/zenith-absorption : O2 and N2
MS: How should Adam’s comment about AI and the people who use it be written so that it is not mansplaining?
JP: Something like
“I realize that you have had a very disagreeable experience on this website that involved people using AI in a way that deeply affected you personally. I don’t see this as a problem inherent to AI, but a problem with some people and the way they choose to use it. “
According to a new study, during El Niño (Discharge Phase), heat distribution is poleward – OHC redistributed. Only read the abstract but found this informative, did not read it this way prior. Is the next step to factor this into weather models for better predictions?
Changes in ENSO-Induced Ocean Heat Content Redistribution under Global Warming
I dunno about weather models but on a related note there’s no possibility that ocean circulation due to all significant pressure anomalies caused by (1) salinity anomaly (2) density anomaly (3) sea surface height (SSH) anomaly are not included in the ocean Model portion of CMIP time-sliced computer simulation climate Models because that is a Very Basic requirement of any ocean Model.
Air & water being fluids transmogrify vertical pressure to horizontal pressure far more readily than slabs of rock in the ground, hence the atmospheric and ocean currents. For example, Kevin Trenberth in 2013/14 in an ENSO talk said the wind (strengthening since 1990) had pushed surface water “4 feet” higher across the west ~1/3rd of tropical Pacific than the central & east ~2/3rds. This taller SSH above a geoid-type Earth ~sphere causes a pressure anomaly of 1,200 kg-gravity-force per m**2 of ocean and the consequent pressure anomaly at all depths to the sea bed MUST cause horizontal ocean acceleration (= Force/anomaly / Mass) until it is balanced to zero, when it still moves until counter-pressure decelerates it to zero. This MUST cause upwelling some place(s) because the water can’t go down because the sea bed and Earth’s interior is in the way. There’s no reason for the pressure anomaly (4 feet tall of water in this case) only to move the deep water east across tropical Pacific, it will obviously cause deep currents which move the water north & south also. This will be a major part of the famous “more heat going into the ocean” public statements circa 2013 years about the “pause” or “hiatus” (I vaguely recall something about the Indian Ocean also getting more deep heat into it).
So, this must have been in CMIP Models, likely earlier also, to whatever extent, accuracy, was available as the years went by since the 1970s. It isn’t at all new to climate Models though it’s undoubtedly getting more accurate as time goes by.
I see that I have not explained my confusion clearly, and for that I apologize, but I am confused, so it’s not surprising. I can’t say I have really understood anyone’s attempts to clear up my confusion. Kobayashi Maru has come the closest, but I thank all of you who tried. But now I have asked Google AIi to weigh in. I asked does the energy from an infrared photon that is absorbed by a molecule of CO2 become thermal energy at the moment it is absorbed. Google AI’s response:
“At the exact moment an infrared photon is absorbed, the energy does not become thermal energy. Instead, it becomes vibrational energy within the CO2 molecule, causing its atoms to bend and stretch more vigorously.
“Thermal energy specifically refers to the kinetic energy of molecules moving and bouncing off one another. The conversion from the absorbed photon’s energy into thermal energy happens in a two-step process:
“1. Absorption: The CO2 molecule absorbs an infrared photon, exciting it into a higher vibrational state.
“2. Transfer to Heat: Before the molecule can re-emit that energy as another photon, it collides with another atmospheric gas molecule (like nitrogen or oxygen). During this collision, the vibrational energy is transferred into kinetic energy (motion) of the surrounding molecules, which registers as an increase in temperature.”
___
First, if that is correct, then I’m not confused, but I am bad at expressing what I mean, because 1 and 2 are what I meant.
But second, I have always thought of 1 as the GreenHouse Effect, and 2 as warming.
And finally, I have also considered the eventual re-emitting of a photon downward to be part of the GreenHouse Effect.
If 1 + eventual re-emitting photons downward is not the mechanistic explanation of the Greenhouse Effect, then what is the mechanistic explanation of the greenhouse effect and does the Greenhouse Effect include the warming?
Martin
Martin
Here’s what NASA says;
“What is Global Warming?
Global warming is the unusually rapid increase in Earth’s average surface temperature over the past century primarily due to the greenhouse gases released as people burn fossil fuels. The global average surface temperature rose 0.6 to 0.9 degrees Celsius (1.1 to 1.6° F) between 1906 and 2005, and the rate of temperature increase has nearly doubled in the last 50 years. Temperatures are certain to go up further.”
So you disagree with NASA?
Zebra: So you disagree with NASA?
MS: No, nothing I wrote disagrees with the NASA statement.. But the NASA statement is not a mechanistic explanation. It’s a description of the result of increasing the greenhouse effect.
Mechanistic explanation:
1. Greenhouse gases trap radiant energy emitted from surface;
2. All gases convert trapped energy to thermal energy by increased collisions;
3. Greenhouse gases re-emit some energy back to surface.
4. Goto 1.
When the amount of greenhouse gases increases, 1, 2, and 3 all increase.
Nope, because you steadfastly refuse to ponder TEMPERATURE of the air parcel and MANUFACTURE of photons by the gases (more with higher temperature than lower, Kelvin**4), decimal orders of magnitude more photons MANUFACTURED by the gases than all photons escaping from the 25 micron thickness of ocean below (the “surface radiation”). This is why you keep aimlessly circling, and getting drawn into esoteric detail from Ray, Tomas & PO27 which is great for ME to ponder (next Winter I think) but useless to “Martin Smith (MS)” because MS stubbornly refuses to start by pondering the Simple, Obvious, Basic. Which is that parcels of the GHGs (say long, wide layers 100 m tall but whatever) MANUFACTURE vast quantities of photons proportional to Kelvin**4, and they absorb vast quantities of photons but NOT proportional to Kelvin**4 (NOT proportional to Kelvin at all).
If you started by having some logic in the thinking, because the molecules EMIT photons, which is the RADIANT “energy” you refer to because it would be silly to say “Greenhouse gases re-emit”
water latent heat energy, or they “re-emit” Sensible Heat energy, or they “re-emit” the significant Solar SWR 54 w/m**2 that also part of the energy that Greenhouse Gases emit NOT “Greenhouse gases re-emit”. Is it a Fetish thing happening?
A simplified explanation of the so-called “greenhouse effect (GHE)” in Earth’s troposphere. Some Power flux of the vast quantity of photons that are emitted (manufactured) by molecules in Earth’s troposphere leak out of its top & bottom into or through the stratosphere and into the surface respectively. Emission (manufacturing) is proportional to Kelvin**4.
=======
Suppose for concept illustration only (not highly accurate) that 194 w/m**2 leaks out the top and that is part of what is emitted (manufactured) by molecules over an altitude range of 4 to 12 km with an effective average of 7 km. Say for concept illustration that 345 w/m**2 leaks out the bottom and that is part of what is emitted (manufactured) by molecules over an altitude range of 0.0001 to 1.5 km with an effective average of 1 km.
=======
Suppose a certain amount of CO2 was added into the troposphere and mixed then *instantly* the upper & lower ranges would need to be closer to their respective ends because there are more CO2 molecules in the way. So the effective averages of 7 km for upwelling into or through stratosphere and 1 km for downwelling into surface change to 7.05 km and 980m respectively, with the upwelling & downwelling Power fluxes consequently changing to 193 w/m**2 and 346 w/m**2 respectively due to being produced by higher-than-before (colder) and lower-than-before (warmer) air parcels. The reason for this is that pressure reduction with increasing altitude causes “adiabatic cooling” or “adiabatic heating” for increasing or decreasing altitude respectively.
=======
There has been no change in the 539 w/m**2 leaving the troposphere, there is no “magical extra energy”, the surface downwelling radiation has increased by 1 w/m**2, which is an additional ~480 terawatts (~95%) heating the ocean and Earth is emitting less radiation to Outer Space (a Power reduction of 510 terawatts).
As I typed in my explanation, in my opinion the “Greenhouse Effect (GHE)” does not include the warming because including the warming brings in lots of other mechanisms that follow what adding CO2 (the obvious suspect, just an example) causes, which is quite trivially simple as I explained in my 4 paragraphs. If there’s now 194 w/m**2 radiative going up from top part of troposphere and 345 w/m**2 radiative going down from bottom part of troposphere, add a certain CO2 amount in the troposphere and immediately it changes to, say, 193 w/m**2 radiative going up & 346 w/m**2 radiative going down. The reason is the temperature lapse rate (gets colder with altitude) and manufacture being according to Kelvin**4.. That’s it!!! The subsequent warming and all the complicated stuff naturally follows the example 1 w/m**2 less going to space and 1 w/m**2 more, the slowly heating the ocean and surface and the lots of other effects.,
This is correct. The only way that anything warms is a difference between energy inputs and outputs.
For the planet this is defined by solar input minus radiative emission to space. That difference, called TOA net radiation, is the energy accumulation. It represents a positive net heat flux into the system. When the solar heating of the planet exceeds radiative cooling, joules start piling up internally. The planet is not cooling at the same rate it is being heated by the sun.
There is no need to mention surface, back radiation, or anything. All the action is at the radiation boundary with space. There is a heating rate, often described in K/day, and there is a cooling rate, in K/day. If these are different the planet is accumulation energy.
https://youtu.be/4PAbm1u1IVg?si=wfxvpHock2TH-g0o
When Joules are piling up, GMST gets dragged along. The surface is an arbitrary level when it comes to greenhouse effects. When stuff is warmer, radiometers detect more signal in whichever direction the sensor happens to be pointing.
The classical insight is that increasing GHG may raise the effective emission altitude into colder layers, meaning the cooling rate of the planet is decreased. Colder things don’t radiate as much. The planet is temporarily made to look colder from space, so it’s not cooling as fast.
Energy accumulates (Joules pile up) until such a time as the temperature at the (new) radiating level is warm enough to enable planetary radiative cooling at the same rate as solar radiative heating. Classically, solar absorbed radiation is held fixed during this process.
That’s not correct. MS inquiry was about the mechanism that generated a “planet is not cooling at the same rate it is being heated by the sun.”
What happens at TOA is irrelevant to that mechanism. The answer to MS is how does the greenhouse effect combined with the enhanced greenhouse effect work (ie rising ghg gases), mechanistically work to increase global warming.
So the commentary about toa makes no difference nor does long term eei. such as ” Energy accumulates (Joules pile up) until such a time as the temperature at the (new) radiating level is warm enough to enable planetary radiative cooling at the same rate as solar radiative heating. Classically, solar absorbed radiation is held fixed during this process.”
Its all besides the point – and ignores the questions put by MS. answers for which are in the ipcc refs.
In the meantime the oceans (and land) have always been absorbing SW solar radiation directly one way shape or form. That process has not changed. That radiative energy is still being reflected as LWR to the atmosphere today.
Please choose your partners for the next dance, ladies and gentlemen.
MS well done. You keep asking the right questions. May I add;
The Greenhouse Effect includes both, but they happen in sequence:
Photon absorbed → molecule excited (vibrational energy).
Molecule either:
Collides → transfers energy to kinetic motion (warming).
Re-emits a new photon (often downward) → that photon is then absorbed by another molecule elsewhere.
The full mechanistic explanation:
CO₂ absorbs outgoing infrared radiation from Earth’s surface, re-radiating it in all directions—including back downward. This delays energy’s escape to space, forcing the lower atmosphere to hold more energy. That extra energy manifests as increased molecular motion (thermal energy/warming) until the system rebalances at a higher temperature.
So:
GHE = absorption + re-emission (radiative trapping).
Warming = the thermal consequence (collisional heating).
You weren’t confused. You had it right. The AI just confirmed what you already knew.
The “Kobayashi Maru” directly contradicted itself with its entire GHE “explanation” at 7 Jul 2026 at 12:06 AM (incorrect) versus its correct statement 5 Jul 2026 at 7:24 PM “An increase in the concentration of greenhouse gases leads to an increased infrared opacity of the atmosphere, and therefore to an effective radiation into space from a higher altitude at a lower temperature. This causes a radiative forcing, an imbalance…..”. The correct one mentions “higher altitude at a lower temperature” implying a change in the MANUFACTURING of photons by the GHGs that can reach Outer Space (correct) and the one I’m responding to has the same banal rubbish as the “Joke Zonderkop”. Too much flailing about by “Kobayashi Maru”.
A simplified explanation of the so-called “greenhouse effect (GHE)” in Earth’s troposphere. Some Power flux of the vast quantity of photons that are emitted (manufactured) by molecules in Earth’s troposphere leak out of its top & bottom into or through the stratosphere and into the surface respectively. Emission (manufacturing) is proportional to Kelvin**4.
Suppose for concept illustration only (not highly accurate) that 194 w/m**2 leaks out the top and that is part of what is emitted (manufactured) by molecules over an altitude range of 4 to 12 km with an effective average of 7 km. Say for concept illustration that 345 w/m**2 leaks out the bottom and that is part of what is emitted (manufactured) by molecules over an altitude range of 0.0001 to 1.5 km with an effective average of 1 km.
Suppose a certain amount of CO2 was added into the troposphere and mixed then *instantly* the upper & lower ranges would need to be closer to their respective ends because there are more CO2 molecules in the way. So the effective averages of 7 km for upwelling into or through stratosphere and 1 km for downwelling into surface change to 7.05 km and 980m respectively, with the upwelling & downwelling Power fluxes consequently changing to 193 w/m**2 and 346 w/m**2 respectively due to being produced by higher-than-before (colder) and lower-than-before (warmer) air parcels.
There has been no change in the 539 w/m**2 leaving the troposphere, there is no “magical extra energy”, the surface downwelling radiation has increased by 1 w/m**2, which is an additional ~480 terawatts (~95%) heating the ocean and Earth is emitting less radiation to Outer Space (a Power reduction of 510 terawatts).
The reasons for the troposphere being colder when higher than before and warmer when lower than before (almost always except Antarctica in Winter, and the Winter Arctic Ocean, quite a lot) are that (1) 68% of absorbed Solar Power (SWR) is absorbed within a few metres of the surface, and only 23% of SWR is absorbed throughout the troposphere, and (2) the 194 w/m**2 that is departing upward from the top, and (3) the pressure reduction with increasing altitude causes “adiabatic cooling” or “adiabatic heating” for increasing or decreasing altitude respectively. Convection and water latent heat from the ocean continuously try to make the GHE, correctly described above, be non existent by making the tropospheric temperature above any place on Earth be the same all the way from the bottom to the top, but they continuously fail to achieve that, to the average failure of 68 degrees colder at the top, for the 3 reasons just detailed.
My “closer to their respective ends because there are more CO2 molecules in the way” might be too pithy. Maybe somebody could suggest wider wording about the peer-to-peer radiative exchanges being a net upward flow for the top & bottom so the distance twixt average emission (manufacture) decreasing, by then decreasing the Kelvin**4 difference for the peer-to-peer radiative exchanges thus decreases the upward Net flux but increases the downward Net flux.
Is there actually any literature out there trying to quantify the given climate effect of water vapor?
I know, I know, people would jump in and point to KT97 or Schmidt et al 2010. In KT97 WV contributes 49W/m2 (net) and 75W/m2 (gross) to the GHE, while in S10 it is 61W/m2 (net) and 96W/m2 (gross). Also you might get a more conflated story including clouds, weather and what not else.
But I would like to stick to the actual question and keep it simple and to the point. WV also has a cooling side, which is well known in the context of neg. “lapse rate feedback”.
So what I am looking for is the consolidated impact of both sides, within the given climate. It seems to me, although I might be wrong, this very important question has never really been considered.
I am more than willing to accept the above figures for the warming part, but if we compare that to some 86.4W/m2 of “latent heat” cooling (as in the NASA Earth Energy Budget), then WV was barely warming at all, or rather net cooling.
“consolidated impact of both sides, within the given climate”. I have this from a scientist a few years ago, probably in an internal Webinar but maybe just in a talk. I recall that he was a climate scientist and said “high confidence” but that’s all I recall.
100% GHG increase or any cause(s) of warming
220% H2O gas GHG increase caused by warming
-110% Tropospheric lapse rate reduction due to H2O gas increase, latent heat
Barry, what did you wanted to convey ? What your three numbers are supposed to mean?
And why that highly-confident self-declared “climate scientist” have listed the FORCING (GHG increase) next to …. the two passive FEEDBACKS, as if their role in climate change was comparable???
The only reason I can think of – is an old denier narrative that human changes to water cycle are as much, or preferably – much more important than mitigation of GHGs emissions.
That’s behind the several -decades old claim of water vapour is responsible for 98% of GW .
This “it’s not GHGs, it’s water cycle!” denialism started in the last century (e.g. the mythical number of water vapour being responsible for “98%” of GW) and still live and kicking today – even here – see the July 6 effort by E. Schaffer above, or the many years of posts by Tomas Kalisz and by JCM – the latter going even further – taking the UN report on “ up to 40% of Earth land being degraded” and blaming it on …. the climate modellers and their “ artificial fixation and overemphasis [of the role ] of “trace gas” [CO2].
Do you really want to get in bed with these guys?
Well, that is a nice misrepresentation. Strangely there is one specific pattern, and I have no clue what that is, but it repeats over and over. Wherever I sense that the consensus position is wrong, the critical position is simply wronger, erring though in the same direction.
In the case of the WV share in the GHE I would say it is vastly overstated. The reason of course being the surface emissivity = 1 assumption. This overstates surface emissions, the GHE, and the role of WV within the GHE. So while Schmidt et al 2010 names 61/96 W/m2 for WV and KT97 49/75, I would estimate it to be only 25/50W/m2.
Anyway, there are good reasons for that and it is exactly the opposite of blaming some 98% of the GHE on WV.
in Re to E. Schaffer, 10 Jul 2026 at 11:02 AM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849684
Sir,
Could you provide reference(s) to the article(s) wherein you present your results and compare them with previous studies on the topic like Schmidt et al 2010, so that the interested Real Climate readers can follow your line of evidence?
Thank you in advance and greetings
Tomáš
ES: In the case of the WV share in the GHE I would say it is vastly overstated. The reason of course being the surface emissivity = 1 assumption. This overstates surface emissions, the GHE, and the role of WV within the GHE. So while Schmidt et al 2010 names 61/96 W/m2 for WV and KT97 49/75, I would estimate it to be only 25/50W/m2.
BPL: Show your work.
Tomas to E. Schafer: “ Sir, Could you provide reference(s) to the article(s) wherein you present your results and compare them with previous studies on the topic like Schmidt et al 2010,”
Nice touch, Tomas – asking E.Schafer, point-blank, to show his published proof for his insinuation that Gavin Schmidt and co-authors paper are wrong and/or intellectually dishonest (E Schafer: “overstate surface emissions, the GHE, and the role of WV within the GHE.“).
Unless, of course, you have done it unwittingly – if you don’t challenge the proofs existence but hope it exist – as a fellow “anything but CO2” denier, hoping you might use E. Schafer’s peer-reviewed paper to advocate the diverting of the research and policies AWAY from the mitigation of GHGs, into studying water vapour from which is a scientific dead-end:
– it does not allow any societal/policy recommendations (since we can’t change WV enough to achieve any meaningful difference to AGW – see the fate of your own Sahara irrigation proposal)
– it won’t improve our climate projections – the effect of WV is already implicitely included in the climate models – hence no NEW insight from running the models and exclaiming: “ A ha! On a fictional Earth with WV arbitrarily forced to be at different levels – the GMST would have been X degrees different! Take that, Gavin Schmidt!”
These are a number of considerations adding up, I discuss them on my site. It is was happens if you replace simplified assumptions with more precise and accurate facts. The emissivity of water is perfect example for that, directly affecting the significance of WV as GHG.
The emissivity of water is 0.91, as I have calculated 5 years ago (based on Hale, Query 1973), consistent with Huang et al 2016, or Baehr, Stefan “Stoff- und Wärmeübertragung”. This correct result is in stark contrast to some bad science, like Wilber et al 1999 (NASA) referenced in Trenberth et al 2008, falsely claiming it was 0.9907!?
It follows the surface of Earth will emit ~360W/m2. With OLR = 240W/m2 the GHE will amount to about 120W/m2 only. I know there is this notion that surface emissivity would barely matter in this regard, because the less radiation the surface emits, the more “back radiation” it can reflect, which is true. Inamndar, Ramanathan 1998 is a good example for that. First they wrongly state “sea surface is within 1% of emitting like a blackbody”, then they include surface reflected LW to their GHE definition (in opposition to their previous work), and then they show a chart (Plate 1) where the GHE is minimal over deserts where they assume very low surface emissivities, thereby again contradicting themselves. There is a lot of confusion. I would say it is actually simple. If there is no GH-agent present and the atmosphere is transparent, there is no “back radiation” either to be reflected by the surface. So yes, it is indeed just surface emissions – OLR = GHE.
This necessary downsizing of the GHE will not affect every GH agent equally. There is zero difference regarding clouds, CO2 and the minor GHGs (O3, CH4, N2O..) get some discount, but the bulk of the difference has to be with the WV continuum. The assumption of course is, that all the radiation emitted by the surface and not arriving as OLR, must have been absorbed and substituted by some GH-agent, which is usually WV. A large part of WV-GHE however is just radiation never emitted by the surface in the first place. Adjusting for this issue, WV does some 25/50 W/m2, maybe 30/55 W/m2.
But then we yet have that other side of WV – shrinking the lapse rate and the GHE with it. Then adding up the numbers, I can not help but to conclude WV must be strongly cooling the Earth..
Tomas Kalisz: “Sir, Could you provide reference(s) to the article(s) wherein you present your results”
E, Schafer: “These are a number of considerations adding up, I discuss them on my site. ”
Good one, E. Schafer! See also:
– Sir, Could you provide reference(s) to the article(s) wherein you present your results that the Earth is flat.
FlatEarther: These are a number of considerations adding up, I discuss them on my site.
ES: The emissivity of water is 0.91, as I have calculated 5 years ago (based on Hale, Query 1973), consistent with Huang et al 2016, or Baehr, Stefan “Stoff- und Wärmeübertragung”. This correct result is in stark contrast to some bad science, like Wilber et al 1999 (NASA) referenced in Trenberth et al 2008, falsely claiming it was 0.9907!?
BPL: Different sources give different figures. Most are very high, including the one you mention. I tend to rely on Konda et al. (1994) which found e = 0.984 for seawater.
You’ve been pushing this “the emissivity of water is 0.91, therefore energy budgets for the climate system are all wrong” for years now. Many of us were here the last several times you did it, such as here, four years ago:
https://www.realclimate.org/index.php/archives/2022/07/the-cos2-problem-in-six-easy-steps-2022-update/
This tactic of bringing up a debating point, having it knocked down, then lurking until you feel it’s safe to bring it up again, never acknowledging that it’s been asked and answered, is a typical denier tactic and is obnoxious and exhausting. Perhaps that’s the goal.
In Re to Piotr, 13 JUL 2026 AT 9:57 AM
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849752
Hello Piotr,
Absence of the sought references on the website run by person named “E.Schaffer” strongly suggests that no such publications do exist.
I am afraid that it is very unlikely that they will ever emerge.
Greetings
Tomáš
Well this is not a guessing game, rather it is about the depth of understanding. Neither Wilber et al 1999, nor Konda et al 1994 provide the proper data
W99 failed in many spectacular ways:
– they did not realize water is non-lambertian radiator, so they are unaware of the difference between emissivity to surface normal (which they discuss) and hemispheric emissivity
– they had no data past 15µm and claimed such data would not exist
– actually they just failed to check the literature, as Hale, Query 1973 provided high resolution data up to 200µm
– instead they “interpolated” the far-IR figure from the 15µm result..
– eventually they tried to calculate an average over the whole thing, and failed even with that
K94 only has a very limited scope..
“Its viewing solid angle was 1°, and the sensitive wave length range was between 8 µm and 14 µm.”
So it is just emissivity to surface normal for the segment 8 to 14µm. Emissivity to surface normal over the whole spectrum is 0.965 btw., and hemispheric spectral emissivity 0.91, as before.
Re: E. Schaffer:
Wikipedia: Sealioning – is a type of trolling that consists of pursuing people with relentless requests for evidence, often tangential
here: the water cycle is a passive feedback, so we can’t change it, and its quantification provides no new insight – since it is already included in climate models.
or previously addressed
BPL to ESchaffer: You’ve been pushing this for years now. Many of us were here the last several times you did it, This tactic of bringing up a debating point, having it knocked down, then lurking until you feel it’s safe to bring it up again, never acknowledging that it’s been asked and answered,
It may take the form of “incessant, bad-faith invitations to engage in debate”, and has been likened to a denial-of-service attack targeted at human beings.”
Ladies and Gentlemen – E Schaffer.
E. Schaffer,
Would the review article Colman & Soden (2021) ‘Water vapour and lapse rate feedbacks in the climate system ‘ be the sort of thing you’re after?
@Roger & Barry
Thx, this is a great summary of known considerations. However, it absolutely does not address the simple question I have put up. Although it states..
“At the same time, in latitudes spanning the tropics through to mid-latitudes, the upper troposphere warms faster than the surface – a change in the vertical “lapse rate” with temperature, enabling the Earth to radiate to space more effectively.”
.. there is not the slightest reflection on the netting of those opposing effects within the given climate system. It is like that CL game PSG vs. Bayern, where you might ask who won and get the answer Bayern scored 4 goals. Now that might suggest Bayern won, but actually does not answer the question. There is still a chance they might have received 5 goals and lost the game, which is exactly what happened btw. Equally so just saying WV was a strong GHG having the largest share in the GHE, avoids the question if it is warming at all. Especially given we know it also has a huge cooling side.
Equally jumping right over to WV feedback avoids the question. At the start one should clarify if WV is warming or cooling, and by how much. I feel like the question is avoided in order to maintain the narrative of a pos. WV feedback. If WV is cooling, and that is what the numbers suggest, it makes little sense more WV would provide (strong) warming..
H2O gas isn’t radiating (manufacturing photons by its collisions) from the top of the troposphere and therefore an increase must cause additional imbalance between its radiation leakage (a very small fraction of its photon manufacture) out of the top versus out of the bottom of the troposphere, the so-called “greenhouse effect (GHE)” in Earth’s troposphere.
E. Schaffer,
I find it strange that you would consider that reference to Colman & Soden (2021) “absolutely does not address the simple question [you] have put up.”
You quote from the ‘I. Introduction’ of Colman & Soden (2021) and complain that your question is not answered, it even failing to provide an understanding of the sign of the combined WV/Lapse-Rate feedback. Yet the sign is well known – the combined feedback is positive. Let me quote from the ‘Abstract’ of Colman & Soden (2021).
Colman & Soden (2021) provide a value for the size of this positive feedback in ‘VIII. Conclusions A. On the strength and consistency of evidence for water vapour and lapse rate feedbacks.’ saying:-
Their Tables 1,2 & A2-1 list various studies with values for the various components of the combined WV/LR feedback. And note that your actual question posed upthread was “Is there actually any literature out there trying to quantify the given climate effect of water vapor?” for which I would consider a review paper such as Colman & Soden (2021) would demonstrate properly that the answer to your question was an emphatic “Yes!!!”
(I should add that the latent heat energy flux of “some 86.4W/m2” you mention upthread is not a direct measure of any feedback. Any change in that value would have a bearing on the strength of the WV feedback but again is not a direct measure of the feedback itself.)
I don’t know why that is, but you are not reading what I am writing. Probably you think it is irrelevant, just glance over it and answer to your own assumption. I am STILL NOT asking about WV feedback, but about the given effect of WV.
We have the WV effect and the enhanced WV effect, which we call WV feedback. That is a base magnitude and the enhancement of said base magnitude. As with AR6 that enhancement is assumed to be +1.8 and -0.5W/m2 and a total of 1.3W/m2. My question is on the base magnitude. How much warming, how much cooling, and the net effect of WV. Again, not the feedback, just the base magnitude.
Clearly this is an important perspective and it seems it has been completely ignored, which makes it only more pressing. Of course the notion is, if it ever had been considered, bad things would have been avoided, but anyway..
And of course the 86.4W/m2 in latent heat are also not a feedback, but a given cooling effect by WV. For instance, as above, we could say WV warms with 49W/m2 (KT97 net figure) and cools with 86.4W/m2, and overall is strongly net cooling. I repeat: WV then is a strong cooling agent, which is a ground breaking perspective. And in science we must not ignore perspectives just because we don’t like them. From that the question would arise: given WV cools and is positively correlated to temperature, how could it be a pos. feedback?
But that is downstream, first really there is the urgent question on whether WV is warming or cooling, and I can not fathom it has never been considered.
E. Schaffer “ whether WV is warming or cooling, and I can not fathom it has never been considered.”
Because, as it has been explained already dozens of times to your fellow “anything but GHGs” deniers (Tomas Kalisz and JCM) – WV and other aspects of the water cycle are merely a passive feedback, not one of the drivers of current AGW. Thus:
1. There is nothing we can do about WV – given the magnitude of the natural water and ridiculously short residence time of WV in atm – we simply can’t change water fluxes enough to reduce AGW in any noticeable amount.
2. Since WV is a strong net positive feedback – the AGW is more sensitive to the GHGs, because WV amplifies the consequences of our action, or inaction, on GHGs:
if we reduce GHGs to cool the Earth – WV will make the cooling much larger, if we do not cut our GHG emissions – WV will make the warming much larger,
Which directly counters the deniers narrative that because there is so much more molecules of WV than GHGs – what we do to GHGs doesn’t really matter, so we can burn as much fossil fuels as the fossil-fuel lobby wants us to.
3. For the main societal responsibility of climate science – informing the mitigation of AGW – there is nothing to be gained from “your direct measure of the WV feedback itself” – since again – we simply can’t change water fluxes enough to make any noticeable dent in AGW.
4. Your WV is already implicitely included in climate models – ergo your “direct measurements of the feedback itself” would provide no new insight beyond what we already know from Schmidt et l. 2010 and other papers.
In other words, since your WV feedback is already included in climate models – what difference would it make if out of, say, the projected 2C of warming, 1.3 C was the result of the WV passive feedback instead of 0.9 C? It does not affect our models (since these 1.3C or 0.9C re the products of these models ). Nor can we do anything about it.
Do you fathom it now?
E. Schaffer,
My apologies for repeatedly misinterpreting you questioning.
To be clear, and so I don’t make a fool of myself again, can you set out precisely what you are hoping to quantify.
You say you want a full account of the impact of atmospheric WV on Earth’s GHE: that is the reduced climate ‘forcing’ if atmospheric WV was reduced to zero and in this regard you specifically mention the inclusion of the lapse-rate feedback in this assessment.
However if the WV is considered as being removed from the atmosphere, the presence of cloud seems a little difficult to imagine without any atmospheric WV. Also the planet will be considerably colder without WV and the effects of surface albedo will presumably increase due to expanded sea ice. In a normal situation a colder planet would also result in ice caps and snow-cover, further increasing surface albedo but these would have been deposited by precipitation so may not be present in your hoped-for assessment. The same could be said for land albedo due to plant-life which does rather rely on water from above, directly or via rivers.
Could you rattle through these other factors to indicate which, like lapse rate feedback, you wish to see incorporated into this assessment you seek.
@Rodger
My original question was on whether this issue has ever been considered. I do know a lot of the literature but certainly not all, and according to my knowledge it was not. Then I asked AI and it too could not name me a single instance either. So that is why I brought up the question here and it seems like everyone is confused just because I am asking.
As to what you say let me clarify: we have attribution and science fiction. In science fiction we say “what if” and then play through different scenarios, consider dynamics and so on. In attribution we assume all other things stay the same and consider the “what if” only regarding the immediate effects. In science, to keep things clean, we only do the latter.
The immediate effect of WV is raising the emission altitude and reducing the lapse rate. That is why WV feedback consists of two components, which are raising the emission altitude (assumed to be 1.8W/m2) and reducing the lapse rate (assumed to be -0.5W/m2). Considering these two effects alone is more than enough, there is no need to complicate things any further.
The very same question applies to the given amount of WV. It raises the emission altitude and it has reduced the lapse rate. We have quantifications for both effects, which are totally negotiable and discussable. But the figures we have indicate WV is a cooling agent, and the only reason this has never been understood seems to be that the very question was never asked. And that is simply embarrassing..
E. Schaffer,
You are saying that you want to quantify the net contribution of WV within the pre-industrial atmosphere’s GHE. This contribution is therefore a component of the GHE which comprises the forcings/feedbacks – GHG+aerosols, WV, cloud & albedo that raised surface temperatures some 33K.
And your question was specifically whether there is literature which provides analysis quantifying this contribution.
Yet buried in your enquiry is a very odd separation of the mechanisms of the pre-industrial GHE and the mechanisms of AGW in the industrial age.
You are seemingly happy that the literature shows the impact of WV under AGW comprises the effects of (1) Increased emissions height (+1.8Wm^-2/K) and (2) Increased lapse rate (-0.5Wm^-2/K). This is a net positive feedback of +1.3Wm^-2/K and would boost any warming from other net forcings+feedbacks by about 50%. So far, smiles all round.
We could then take a back-of-envelope approach here and say that the pre-industrial GHE resulted in something like +33K (this requiring surface albedo assumptions) so the contribution of WV would be a net positive feedback of [+1.3 x 33 = ] +43Wm^-2.
Of course it is a big assumption using an unaltered Wm^-2/K of feedback all they way down to zero WV but it does give a ballpark idea of the size of the feedback. The two references you made upthread also give a value for the WV feedback contribution to the pre-industrial climate..Kiehl & Trenberth (1997) ‘Earth’s Annual Global Mean Energy Budget’ give +59Wm^-2 (75Wm^-2 clear sky, 51Wm^-2 cloudy sky, 67.5% cloud fraction from CERES) while Schmidt et al (2010) ‘Attribution of the present-day total greenhouse effect’ give +49 Wm^-2 (All Sky 50% of ‘total’ using K&T(1997)’s 98Wm^-2 ‘total’).
So this is all pretty-much in the same ballpark.
But instead you seem to be of the opinion that the WV value of these two papers doesn’t include the Lapse Rate feedback. And if the +1.8Wm^-2/K from above was applied to the full 33K pre-industrial GHE it would amount to some +60Wm^-2, still in the same ballpark.
But you also consider the -86Wm^-2 surface latent heat flux to be a measure of the full pre-industrial Lapse Rate feedback. This is certainly not the case. The -86Wm^-2 surface flux is converted to sensible heat when the WV condenses up in the atmosphere. It is thus decreasing the Lapse Rate but it is not a measure of the Lapse Rate feedback.
I think I will need to examine your website to find out why you have made such an egregious error. I note from a passing visit that you weren’t not shy about this matter posting about it at the back-end of last year with OPs titled ‘How “Climate Science” has its eyes wide shut on the statistical blunder that generates false positive feedbacks’ and ‘How to Flip the Sign on Feedbacks’
@Rodger
First of all it is great to finally get to my actual question, after 40+ posts here.. ;)
“But you also consider the -86Wm^-2 surface latent heat flux to be a measure of the full pre-industrial Lapse Rate feedback. This is certainly not the case. The -86Wm^-2 surface flux is converted to sensible heat when the WV condenses up in the atmosphere. It is thus decreasing the Lapse Rate but it is not a measure of the Lapse Rate feedback.”
Let me ask: there are a number our sources pointing out the GHE is dependent on the lapse rate, and furthermore proportionate to the lapse rate. If the lapse rate was 0, the GHE would be 0, as surface- and emission temperature would be equal. Equally if the lapse rate was 50% larger, the GHE would be 50% larger. Let us say the average emission altitude was 5km up, then with 6.5K/km the GHE = 6.5 x 5 = 32.5K. With a lapse rate of 9.8K/km it would be 49K. Do we agree so far?
Due to the SB-law we can not directly relate delta temperature into delta radiation, but that is a side show. Yet, by and large, 50% of some 155W/m2 gets us to around 80W/m2. Either way, if it was not for this reduction of the lapse rate, Earth would be a lot hotter. And of course it is physically exactly the same as the lapse rate feedback featured all over the models.
So how exactly do you reject this connection?
E. Schaffer,
Having “g(o)t to {your) actual question, after 40+ posts here” (and I’m not sure having apparently “got to” it, whether you have ‘got over’ it), you then toss in another question!!!!
And what a question! It seems you wish to upgrade the atmospheric Lapse Rate into the primary feature of a GHE, rather than it being the GHGs in such an atmosphere.
And why not? Hey, does not a telescope have two ends?
A Lapse Rate forms in an atmosphere because atmospheric pressure decreases with altitude and gases will generally rise/fall adiabatically within such an atmosphere with meridianal temperature gradients.
In Earth’s atmosphere this zero-GHG base-line Lapse Rate is usually given as 9.8°C/km with the mention of it being “dry air”. The difference for ‘wet air’ that isn’t condensing out precipitation is pretty similar as the decrease in density is balanced by the increase in specific heat capacity.
But adding in a bit of ‘thermodynamicity’ will alter the Lapse Rate due to GHG energy fluxes which warm/cool said atmosphere.
Thus with altitude, GHGs will be emitting/absorbing less IR with the lower temperatures at altitude, this adding warmth with altitude and reducing the Lapse Rate, or shooting IR out into space and cooling the atmosphere, thus increasing the Lapse Rate. Or absorbing incoming UV which in the thin upper atmosphere can warm enough to reverse the Lapse Rate. And precipitation will transport insensible heat up to the point of condensation where it will again provide warming, reducing the Lapse Rate.
The GHE is not just a GHG-thing. It requires a Lapse Rate and that requires atmospheric pressure to decrease with altitude. Mars is a good example of what you get without atmospheric pressure. It has the same burden of CO2 as Earth but this is 95% of its atmosphere rather than Earth’s 0.05%. The result is zero GHE on Mars.
So physics tells us the Earth’s tropospheric adiabatic Lapse Rate sits at about 9.8°C/km before the GHGs start their influence. And what if the total Lapse Rate feedback (‘total’ = today relative to zero-GHG) happened to be 80Wm^-2 (thus equal to the “evapero-transpiration” flux in Fig 7 of Kiehl and Trenberth (1997))? If it were 80Wm^-2, that would be half of the 155Wm^-2 total GHE “Net LW Absorbed” set out in Schmidt et al (2010). And would that then imply the modern Lapse Rate is half the 9.8°C/km? After all, Wiki-thing tells us
the actual average value is considered to be 6.5°C/km up to the tropopause, so not massively different to 4.9°C/km.
(One point to clarify here is that Schmidt et al (2010) do not adjust the atmospheric temperature profile, saying their modelling is “holding the climate (spatial and temporal distributions of temperature, surface properties, etc.) fixed.” and is thus using Lapse Rate data that would presumably reflect that 6.5°C/km average. The WV feedback with no LR feedback would this be some (60Wm^-2 / 33K =) +1.8Wm^-2/K which is the value for the modern climate we see in the literature.)
I think it would be wise to consider all the energy fluxes into the atmosphere. They surely would all be messing with the lapse rate. ☻ There’s the “evapero-transpiration” flux of 78Wm^-2 which would be operating at the points of condensation and which may be mainly impacting the Lapse Rate up to the altitude of WV IR emissions to space. Would the Lapse Rate be reduced above that point? ☻ There’s “thermals”, a flux of 24WM^-2 (with big ‘error bars’) which presumably would be reduced if the Lapse Rate declined. ☻ There’s a net flux of 40Wm^-2 in “surface/back radiation”. ☻ And into the atmosphere from above is an “absorbed by the atmosphere” flux of 67Wm^-2. ☻ Finally there is a cooling flux of 195Wm^-2 “emitted by the atmosphere” which will presumably be increasing the Lapse Rate.
So it looks like the “evapero-transpiration” flux is not the only flux messing with the Lapse Rate. All these energy fluxes look like being of significance to the Lapse Rate.
And together they will have modified the Lapse Rate by altitude and as well as zonally. So I’d suggest that assuming the Lapse Rate is a constant average 6.5°C/km throughout the troposphere doesn’t look like providing a realistic or useful model.
I also don’t see any support for your contention that climatology is ignoring the Lapse Rate feedback or that the combined WV/LR feedback is negative.
We could look at evidence of an increase in global precipitation as a measure of the change in that 78Wm^-2 “evapero-transpiration” flux under AGW. Use satellite data 1979-2020 from GPCP, Gu & Alder (2022) find precipitation rising at 1.4%/deg C. That would be about half the rate of the 78Wm^-2 over 33K.
And perhaps it would not be torturing the available data too much to use the -0.5Wm^-2/K calculated for today’s LR feedback and then double it over the 33K of pre-industrial GHE yielding 33Wm^-2 for the ‘total’ LR feedback and thus (+60 – 33 =) +27Wm^-2 for the combined WV/LR feedback. Note it is positive. Of course, this the opposite of the contention set out in a handful of OPs on you website which look like they could do with some serious debunking.
“86.4W/m2 of “latent heat” cooling” would be local surface and whatever (hundred or so?) metres of air cooling of the tropical ocean only and not at all the globally-averaged tropospheric lapse rate effect. There’s adiabatic heating of descending air by the pressure increasing. I pondered this briefly a few years back about the Hadley Cell, Desert Zone and the incorrect simplified phrasing for requirement of entropy increase (2nd Law if the system was closed) “hotter things heat colder things”, which simplified phrasing isn’t correct of course because latent heat. Specifically I wondered a few minutes. air rises over tropical Atlantic Ocean (tall troposphere, surface Low Pressure Zone), slides north near troposphere top, turns east, H2O gas condenses-freezes high up, rains back onto the Atlantic Ocean having converted latent heat to “heat”, descends over the Sahara Desert nice and dry from having rained out, warms at 9.8 degrees / km altitude by pressure increase and heats a surface of say 40 degrees from Atlantic Ocean surface of say 25 degrees. Hotter warming colder due to latent heat.
Oh no, that is indeed the global average estimate.
https://mynasadata.larc.nasa.gov/basic-page/earths-energy-budget
You need to bear in mind what it means. It is not just latent heat as an arrow in the diagram above, but rather it means the reduction of the lapse rate and the whole GHE with it. Without WV we would have a dry unstable adiabatic lapse rate of >9.8K/km. The GHE would be at least 50% larger. If you assume it to be 155W/m2 that would mean over 77.5W/m2.
In my calculation the GHE is only 120W/m2, but the lapse rate should actually be like 65% larger, so that the latent heat would still amount to ~80W/m2.
In 2013 I calculated 79 W/m**2 from annual global precipitation and evaporation latent heat per kg. I just did it again in 1 minute and got only 76 W/m**2. In 2013 Kevin Trenberth showed 80 W/m**2 in his EEB at 26:26 at https://www.youtube.com/watch?v=SQOIHdlZngk so I assumed my 79 W/m**2 was simply latent heat off the oceans. Are you referring to 86.4 – 80 = 6.4 w/m**2 as meaning that some adjustment is needed to the total effect of increased H2O gas due to increasing surface-troposphere temperature ?
No, I am not into claiming some super precise figure here. I just point out to the fact that there is some 80W/m2 (or so) of cooling due to WV, which depending on what figures you choose, is at least on par, if not exceeding, its warming side.
Nuts. “Hotter warming colder” S.B. “Colder warming hotter”
In Re to Barry E. Finch, 12 JUL 2026 AT8:22 AM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849729
Hello Barry,
I am not sure if I understood you correctly but, if you assume that latent heat stored in water vapour released from tropical oceans and rainforests returns to Earth’s surface in deserts of higher latitudes, I would like to ask how is it possible that the warm air heated by water vapour cindensation descends?
Do you not think that already the said condensation (and following precipitation) of Ester vapour could hardly occur if at least part of the released condensation heat were not emitted as infrared radiation to the space?
I suppose that the same may apply for further cooling of the resulting dry air that enables its final descent to the ground.
Water, not Ester. Condensation, of course.
Tomas, “how is it possible”. Hadley Cell, large scale overturning. “at least part of the released …. emitted as infrared radiation to the space?” Yes, of course, and I doubt I’ll ever try to figure that out with any worthwhile accuracy (few years back I tried to estimate global wind turbines slowing global wind in my head in my kitchen making dinner, and I gave up, couldn’t figure the constant push of uneven Sun heating of Earth fighting an attempt to slow wind). So that’s why I simply gave in my comment 6 Jul 2026 at 8:13 PM what I saw in some scientists’ Webinars (2 I think I recall) on UTube where they showed the classic 3 feedbacks and Planck response (probably the Webinars were about how cloud feedback is known poorly and the surface better and +H2O gas feedback with high confidence) from some average of some CMIP Climate Models. I figure the odds the Being-Paid scientist Army and computer programmers did that with their time-sliced simulations better than I could with some calculations to be like 1,234:1 and the odds for better than “E. Schaffer” like 9,876,543:1 (even though some of those bods think photons is re-emitted and they ain’t and radiation some place goes back some place and it don’t) because I’m not finding “E. Schaffer” to be making any sense at all.
Tomas, I just realized that “E. Schaffer” 13 Jul 2026 at 6:30 PM “the fact that there is some 80W/m2 (or so) of cooling due to WV” is mostly (the other little bit is my estimated adiabatic heat to surface) yet another of the Denier memes enabled by the physicist nonsense “re-emits” and “back radiation” instead of “emits (manufactures)” and “downwelling radiation at the surface”. Ironic that I failed to notice that considering I’ve been going on about it and getting “Flamed” since June 23rd when I correctly pointed out that some bods typed rubbish. I forgot that downwelling radiation at the surface includes I just calculated 16% of the H2O evaporation-condensation-freezing latent heat. As you also understood in a comment the LWIR in troposphere is from all Power sources.
The “80W/m2 (or so) of cooling due to WV” hasn’t itself, with that hugely-overstated “80”, gone through the “greenhouse effect (GHE)” in Earth’s troposphere, with GHGs converting Solar SWR. H2O gas latent heat, and NET sensible heat convection & conduction into LWI radiation and returning 63% to the surface. Using the “Hartmann 2nd Edition 2016” text book page 34 EEB diagram with my assumed 13 w/m**2 Solar SWR each into thermosphere & stratosphere, in Earth’s troposphere is 54 of Solar SWR + 27 of rising warm air + 88 of surface water evaporative latent heat + 376 of surface LWIR = 545 w/m**2 total so the 88 w/m**2 of surface water evaporative latent heat is 16% of the Power sources for making the LWIR. So 16% of the 345 w/m**2 = 55 w/m**2 of the downwelling radiation at the surface is evaporative cooling at surface being returned to the surface as LWIR.
I looked at Hartmann page 166 annual overturning mass stream functions for all of 3 minutes and estimated 7 w/m**2 of adiabatic cooling while ascending & heating while descending, which might be highly miscalculated, from the diagram. Added 7 to the 20 w/m**2 of thermals. So, the actual water evaporative cooling at the surface to compare for scale with the total “greenhouse effect (GHE)” of H2O gas in Earth’s troposphere is 88 – 55 – 7 = 26 w/m**2.
I think you are somewhat struggling with the GHE itself. It is simply the difference between surface- and emission temperature, or respectively surface emissions and OLR. So that is 288 – 255 = 33K, or 390 – 240 = 150 respectively. We could discuss the precise figures here, but that is the idea.
In both instances the lapse rate is decisive for the magnitude of that GHE. Again, if the lapse rate was zero, there would be no GHE at all. And we know because of WV, because of the latent heat, we do not have a dry unstable adiabat (>9.8K/km) but only just ~6.5K/km. So yes, this latent heat DOES cool the planet a lot, easily by an 80W/m2. It ain’t that complicated..
“”55 w/m**2 of the downwelling radiation at the surface is evaporative cooling at surface being returned to the surface as LWIR”””
I wager this is misleading. The main determinant of surface LW down is lower atmospheric temperature, not instantaneous flux.
Climatological temperature at some level is determined by todays planetary solar heating, yesterdays solar heating, and all the days before, minus the LW cooling of the planet on all the days. So we arrive at some cumulative sum of energy absorbed and emitted by the planet, and allow thermodynamic and heat properties to sort out where all this energy ought to go and by association how much temperature at some level should be dragged at some point in time.
Strictly speaking, the immediate power source for atmospheric LW emission is the thermal internal energy of the atmosphere. Jiggling molecules and so on. Over climate timescales, that internal energy is ultimately maintained by the net external radiative energy entering the Earth system (absorbed solar minus outgoing longwave from the perspective of space). When N = 0, the change of internal energy (U) is 0. LW emission is a function of U.
Consequently, saying that latent heating of atmosphere contributes roughly 16% of the atmospheric energy input does not imply that roughly 16% of the surface downwelling longwave “comes from” latent heat. If the partitioning between sensible and latent heat changed while the lower atmospheric temperature remained unchanged, the surface downwelling longwave would remain approximately the same. Conversely, if latent heating decreased but the lower atmosphere became warmer, downwelling longwave would generally increase. The 16% figure simply says something about the state of the system.
If still not convinced, the attribution of LW down to the latent heating is non-unique. It depends only on the accounting framework. I think the issue becomes more clear when using a surface budget, since taking a valid closure equation should not be interpreted it as an attribution equation. Those are not the same thing. The budget tells you only what combinations of fluxes satisfy energy conservation.
Classically the surface budget is written as SW down – SW up + LW down – LW up = H + LE. It says surface net radiation = fluxes of latent and sensible heat.
SW down – SW up + LW down – LW up – H – LE = 0.
Now just rearrange for clarity to understand why it cannot be an attribution.
LE (latent heat of evaporation) = SW down – SW up + LW down – LW up – H.
Now suddenly latent heat flux might seem to depend on LW down, and not be causing it. How can that be.
Now make things really weird:
LW down = SW up – SW down + LW up + H + LE.
Now it seems like LW down has some inverse relation to SW down, which is really weird. Why would increasing SW down decrease LW down? It’s weird because it’s not an attribution, it is simply relations which must satisfy energy conservation. It is a closure relationship, not a physical decomposition of the origin of the downwelling longwave radiation.
Putting elements on one side or another of an equals sign does not assign cause and effect. Physics doesn’t work like that.
The same thing is happening in atmospheric budgets. It is not correct to understand latent heating of atmosphere to be causing LW down, even though at first glance that seems perfectly reasonable. I recommend sticking to the original message, which is that radiation is manufactured simply based on the state of the system. The immediate physical origin of downwelling longwave radiation is the thermal internal energy of the atmosphere. I think somehow this message is being overlooked.
To Schaffer
as always the reality is always a little bit nuanced.
It is obviously true that when greenhouse is described as an observational temperature difference it represents a type of radiative convective equilibrium with all its complexities. I think it shouldn’t be in dispute.
Owing to the freedom of non radiative heat transfer, we know the temperature gradient is diminished compared to what it otherwise might be in a purely radiative equilibrium profile.
The other part is about the depth of surface below the balancing radiative emission level. This can be understood to be associated with the atmospheric composition and its relation to optical thickness.
Flux of mass and heat says something about temperature profiles, and column water vapor says something about the spatial separation of surface and the planetary radiating level along that profile.
For investigation of how a model deals with worlds with varying restrictions on moisture dynamics, including column water vapor state and the cycling aspect associated with flux of mass and heat, I recommend “Continental configuration controls the base-state water vapor greenhouse effect: lessons from half-land, half-water planets” https://eartharxiv.org/repository/view/5196/
There we see 8 different configurations, ranging from landworld, which is basically totally restricted in moisture cycling, to aquaworld which is totally ocean, and things in between, including tropicalland, northland, and realLand. Each has different shapes and distribution of land and ocean. Fig 1. This is meant to illustrate that it matters where and how much moisture is limited or not.
These simulations handle both the features of turbulent flux of heat and mass, and water vapor concentration. Clouds are not discussed, which aligns with the talking points so far on the thread. The range across simulations is about 15K.
There we see how landWorld, despite having extremely limited latent heat flux, exhibits the coldest mean temperature of all simulations Fig 2. Total column water vapor is close to negligible at 3.9 kg Fig 5, and the planet settles around 273K.
The opposite configuration aquaWorld, totally ocean, settles at 285K. This features the greatest partitioning of surface energy to latent heat flux and includes 17.1 kg column WV.
The realLand shapes, which depict relatively complex distributions of land and ocean, generate the warmest temperatures of all 8 simulations at 287K. The partitioning of latent flux is more restricted compared to Aqua, and yet the column water vapor climbs to 17.2 kg.
landWorld cold, aquaWorld medium, and realWorld warm.
I hope it provides a foundation to think about how the heat flux and WV are somewhat related but definitely distinct issues, and how the associated dynamics can interrelate in counterintuitive ways.
cheers
Perhaps unclear, I didn’t mean that the 86.4W/m2 Power flux is only for the tropical ocean, I know it’s a globally-averaged value of 44.1 petawatts (44.9 in my Hartmann text book, (40.3 or 40.8 I recall from earlier EEB pictorials). I meant that the 44.1 petawatts of surface water evaporative cooling must be reduced by (8% I just very-roughly calculated) due to descending air being adiabatically heated and H2O gas condensing-freezing must be given its allocation of that sensible heat downward at the surface. I’ve since realized that I forgot the effelump in the room for that which is that downwelling LWIR at the surface includes 16% of its Power from the upwelling evaporation of the ocean and that means that surface water evaporative cooling must be reduced by a massive 64% (63% for the Hartmann EEB) because that much heat that left the surface as evaporative cooling returned to the surface as LWIR.
An interesting paper in the journal Nature ‘Amplified Arctic iceberg traffic reshapes benthic biodiversity’ and a news story about it remind me how climate change is terrifying, but climate science is fascinating. Scientists looked at dropstones, rocks that start embedded in glaciers, broke off into the ocean in icebergs, then were deposited on the ocean floor as the icebergs melted. They were able to use the recordings of seabeds as a proxy to determine how fast glaciers were breaking up in some areas. They also recorded the ecosystem changes caused by the dropstones. Organisms that needed hard surfaces to live on were increasing as the ecosystems changed from soft sand or mud to hard stones and rocks.
News article:
https://www.nytimes.com/2026/07/07/science/arctic-icebergs-deepsea-life.html
The paper, its freely available
https://www.nature.com/articles/s41586-026-10630-4
Copernicus has posted for June ERA5 re-analysis with the month’s anomaly of +0.56ºC, this the second warmest June on record.
The top-ten ERA5 Junes now run:-
2024 … +0.67ºC,
2026 … +0.56ºC,
2023 … +0.53ºC,
2025 … +0.47ºC,
2019 … +0.37ºC,
2020 … +0.36ºC,
2022 … +0.31ºC,
2016 … +0.26ºC,
2018 … +0.23ºC,
2021 … +0.21ºC.
Globally, 2026 started warmer than 2023 but cooler than 2024 and now, mid-year, the three are equally warm at about +0.6ºC. The Dec 2023 and 2024 anomalies sat at about +0.8ºC.
This pretty-much echoes the NH situation, with the 2023 and 2024 NH anomaly tracking each other very closely from mid-July to year’s end. Down in the SH 2026 has been tracking the slow drop seen in 2025, cooler than 2024 and since May a tad cooler than 2023 (which saw a sharply rising in anomaly Jan-to-October).
I should mention that the SH anomaly is subject to big Antarctic wobbles which run throughout the year. (Up north, big Arctic wobbles are restricted to winter months.) The Antarctic wobbles do look to have contributed a significant cooling within the SH average anomaly through June.
The Copernicus numbers include a value for “relative to the 1850–1900 pre-industrial.”
Until the extra highlighting employed in this month’s update, I hadn’t managed to notice before the link to “Read more about how the temperature change above the pre-industrial level is estimated and the differences between global temperature datasets.” This provides explanation of the method used by ERA5 to calculate its 1850-1900 anomaly base (given the ERA5 record only runs back to 1940).
The method uses the average of BEST, HadCRUT & NOAA (which do cover the 1850-1900 period) that yields the annual offset of -0.88ºC relative to the ERA5’s 1991-2020 base. Monthly average offsets (which show an annual variation, -0.77ºC to -0.98ºC) are then used to calculate “objectively using Fourier fitting of a single harmonic, rounding coefficients to two decimal places” for monthly offsets and, with a bit of additional smoothing, daily offsets.
UAH TLT has posted for June (the first measured June data) with an anomaly of +0.46ºC, down on May’s +0.53ºC. The NH showed a healthy increase (May +0.46ºC, June +0.54ºC).while the SH a bigger decrease (May +0.60ºC, June +0.38ºC).
The July NOAA ENSO: Recent Evolution is posted. The RONI numbers show AMJ 2026 at +0.5, this a little behind the 1997 and 2015 El Niños, although the Central Pacific OHC pretty-much tracking 1997-98 and well above 2015-16 etc.
The above could be compared with 10 days ago – MA Rodger says 30 Jun 2026 at 2:26 PM
–how June 2026 (+0.55ºC) will be roughly unchanged from May26 and marginally above the Jan-May average (+0.53ºC). (Recent year Jan-Jun have averaged 2023 +0.38ºC, 2024 +0.70ºC, 2025 +0.61ºC),
–The SAT numbers wouldn’t be showing any sign of the coming El Niño while the ERA5 60N-60S SST so far continues the pause seen during May26
— so the presently-developed El Niño conditions would be rated as ‘weak’.
–a 2-in-3 chance of ‘very strong’ El Niño conditions (RONI>2.5) by November.
https://www.realclimate.org/index.php/archives/2026/06/unforced-variations-june-2026/#comment-849502
June 2026 was the hottest June recorded for western Europe and the second warmest globally.
It saw near-record temperatures driven by the highest sea surface temperatures (SSTs) on record for the month,
https://climate.copernicus.eu/copernicus-record-heatwave-brings-hottest-june-western-europe-during-second-warmest-june-globally
June 2026 was the second-warmest June in analyses of global weather data going back to 1850
a 95% chance that 2026 will rank among the four warmest years on record.
NOAA expects a very strong “super” El Niño event
https://yaleclimateconnections.org/2026/07/june-2026-earths-2nd-hottest-june-on-record/
and
https://climate.copernicus.eu/surface-air-temperature-june-2026
and
There is a new El Niño out there and it was officially declared already on June 11 by NOAA.
This is both unusually early in the year and very soon since the last El Niño in 2023-24.
Another remarkable thing is the seasonal forecasts, which for a couple of months have indicated that it may well be at strengths by the end of the year that we have not seen before.
All these three aspects combined seem to make this El Niño different to the previous ones.
https://www.realclimate.org/index.php/archives/2026/07/this-new-el-nino-is-different/
The idea of an impending El Niño is particularly interesting to me, as I’ve experienced its effects firsthand on my beach travels. I’ve found that off-season trips can be a great way to avoid the crowds and heat waves that often come with these events. For instance, I once took a ferry to a remote island during the off-season and was able to explore its beautiful beaches without the throngs of tourists. One practical tip I’d like to add is to always research the necessary permits and timing for these trips, as they can vary greatly depending on the location and time of year. I’m wondering, how do you think the impending El Niño will impact beach ecosystems and coastal communities, and what can we learn from past experiences to better prepare for its effects?
Rohit, how very nice for you. I’m glowing in empathetic pleasure.
I retract that because “Rohit Ghosh” isn’t Climate Systems Scientist “Paul Beckwith” flying Canadian Winter to Florida for a blitz round the Everglades at 99 miles per hour in a 15 ton Power Boat then back to Ottawa for more science videos about the ‘orrible Climate Changes, and ask for some more money.
GISTEMP and NOAA have posted for June. (Numbers-wise, there’s little difference except in the SH.) NOAA’s “June Highlights” run:-
☻ The globe had its second-warmest June on record, driven by global ocean surface temperatures reaching an all-time high for the month.
☻ Both the Arctic and Antarctic recorded June sea ice extents that ranked among their respective 10 lowest extents on record.
☻ Global tropical cyclone activity was above average with seven named storms. (Note the Atlantic is having a quiet start to the season.)
For June (+1.18ºC), GISTEMP shows a small rise on May’s anomaly (+1.13ºC) with an increase in the NH (May +1.30ºC, June +1.44ºC) and a smaller decrease in the SH (May +0.97ºC, June +0.92ºC).
The 2026 anomalies for May & June both sit above the 2025 May & June so the rolling 12-month average is now bottomed out and on the rise. And I reckon that we are now starting to see them up-tick with the coming El Niño. Compared with 2023, it’s a relatively gentle up-tick and not yet appearing in the wholly-SAT record of ERA5 (although in the 60N-60S SST of ERA5 anomalies have been on the up for some time).
<a href="https://sites.google.com/site/housman100resultstemperarypost/home/the-banana-watch"<The Banana!!! Watch page monitors these temperature developments.
E. Schaffer 10 Jul 2026 at 10:59 AM ” I am … asking about the given effect of WV”. That’s a topic to which applies “Point of view” not socially but from a physical science basis because there are mutual.ly-reinforcing effects. A big one is ice-snow cover. The simplifying statement that Earth would be ~33 degrees colder without CO2 must be highly incorrect because ice-snow has a much higher albedo than ocean water so a reduction of CO2 to the point where the ocean is mostly or entirely iced over must make Earth far colder than just ~33 degrees colder.
Since H2O gas is a condensing gas in the troposphere it must be considered a feedback, not a Forcing, and thus its contribution to Earth’s GMST, cannot logically be in a separate category from the surface albedo “effect” on temperature and cloud “effect” on temperature.
So, if Earth goes from Snowball Earth to Holocene Earth there’s no single division of warming “effect” on temperature rise because change in open ocean water portion affects H2O gas, and CO2 also, and change in well-mixed GHGs and condensing H2O gas affects the open ocean water portion.
Also, if some emission (manufacturing) and absorption spectral lines are shared by CO2 and H2O gas, rather than being interleaved, then the allocation of “effect” is arbitrary or decided by physics that’s past what I’m willing to spend time pondering.
Barry: “ if some emission (manufacturing) and absorption spectral lines are shared by CO2 and H2O gas, rather than being interleaved, then the allocation of “effect” is arbitrary or decided by physics that’s past what I’m willing to spend time pondering
It has been already discussed in Schmidt et al. 2010 – where they pointed out – that “direct measure” of warming by any substance influencing the climate – does not have a single value – because even if a given factor was removed, other factors with overlapping windows of absorption would partly compensate by increasing their own absorption. To make things worse not only there is no way to subtract this compensation – the % of compensation would be different in moments in time.
And that’s on top mentioned by you: passive feedbacks (like WV) and not the same as forcings (anthropogenic GHGs) and there is no point in calculating “direct measure” of feedbacks, other than the deniers trying to divert the attention from the mitigation of GHGs and allow fossil fuel political- industrial complex to extra as much fossil fuel as their shareholders, and cost of waging wars on other countries, demand.
You are right in stating the 33K (or so) are not enshrined in law. They are supposed to be the difference between surface- and emission temperature, that is all.
It is indeed incorrect that the Earth would be 33K colder without CO2, for lots of reasons. We have other forcing GHGs like O3, CH4 or N2O – it is not just CO2. The largest contributors to the GHE however are clouds and WV, which both have their cooling sides. If you’d remove them you would not just lose their contributions to the GHE, but also change the albedo and the lapse rate.
A simple calculation might look like this: The energy budget would go from 240W/m2 to 290W/m2 if you lose cloud albedo. The non-condensing GHGs (CO2, CH4, O3, N2O..) might contribute about 50W/m2 to the GHE (single factor addition), at the given lapse rate. Without WV this lapse rate would be at least 50% larger, let us say it would be 80W/m2 then. Also we know the surface as it is does emit ~360W/m2.
Without WV and clouds we get 290W/m2 in and 280W/m2 out (360-80), that is an energy SURPLUS(!!!) of 10W/m2. That is if we’d remove WV and clouds from the atmosphere, the Earth would warm.
ES: It is indeed incorrect that the Earth would be 33K colder without CO2
BPL: More of a strawman. The Earth would be 33 K colder without the entire greenhouse effect, not without CO2 in particular.
ES: if we’d remove WV and clouds from the atmosphere, the Earth would warm.
BPL: Congratulations on the nuttiest denier idea I’ve heard around here lately.
Please do feel free to cite the peer-reviewed publication in which these claims are substantiated.
in Re to E. Schaffer, 10 Jul 2026 at 10:59 AM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849683
Sir,
I am afraid that the way how you framed your question (like “Is water vapour cooling or warming Earth?” or “Is water vapour cooling or warming Earth’s surface?”) may prevent any reasonable answer.
On the first sight, it appears that your formulation reduces the role of water in Earth climate to its vapour, what would suggest a primary focus on the greenhouse effect of water vapour. However, if you perhaps consider also the role of water in lapse rate regulation and/or in cloudiness regulation (what seems to be the case based on your complaints that your request is not taken seriously), you should not speak about “vapour”.
Instead, I would expect that you will analyse the relationship between water cycle intensity and geographical distribution of water availability for evaporation, including their complex interactions with other components of the climate system and processes therein. This way, you could perhaps arrive at some hints if (and/or under which circumstances) the assumed summary “cooling” or “warming” effect of various forms of water (and/or various processes involving water vapour formation and condensation) on Earth’s surface prevails.
Nevertheless, I do not think it would be sufficient. Furthermore, you should consider also climate aspects related to water heat capacity, heat distribution by ocean currents, and properties and behaviour of ice. Finally, you should not neglect also underground water as well as water distribution in soils and vegetation, and in all these instances keep in mind that all forms of water interact with water vapour and that these interactions and processes involving them are no way static.
For these reasons, I can hardly imagine how this complexity could be reduced to the requested unambiguous estimation if the “effect of water vapour” is “cooling or warming”. I doubt that such generic request makes sense.
Best regards
Tomáš
Yes, that sounds indeed very complicated.
I guess we could go down this path, or we just stick to the pretty simple reality. In this simple reality WV does two things:
– it raises the emission altitude, thus reduces the emission temperature, which enhances the GHE and warms the planet
– it reduces the lapse rate, thus increases the emission temperature, which reduces the GHE and cools the planet
And almost as if I had to repeat myself (lol), the question is about netting those two effects. And again, I can not believe this question was never dealt with and comes across as if it was an alien spaceship. This should be trivial!!!
You are forgetting the fact that water vapor is a potent greenhouse gas in its own right.
“You are forgetting the fact that water vapor is a potent greenhouse gas in its own right”
Yes, by elevating the emission altitude, which I just pointed out. But it also has that other side..
E. Schafer: “ we just stick to the pretty simple reality., ”
.the simple reality that we ALREADY KNOW that we can’t do ANTYHING about WV, clouds and lapse rate to mitigate AGW in any meaningful way?
Nor will it improve our knowledge – VW, clouds and lapse rate are already implicitely included in the climate models. If the model show 2C warming what difference does it make to ask how much of that 2C came from direct forcing (GHGs) and how much from the passive feedbacks (water cycle).
Instead, we should stay focused on plausible scenarioes of mitigation of GHGs, instead of pondering futile questions like what the Earth would look like “if we somehow could remove both all WV and clouds“. Particularly when we already know that raising temperature with GHGs tends to decrease clouds, but increase WV.
Well, it is exactly about improving our knowledge, and decisevely so.
A Schafer: ” it is exactly about improving our knowledge, and decisevely so.”
I have shown the opposite – as all deniers’ narratives:
– it has a NEGATIVE societal value – not only does provide any useful information to deal with existential threat to our civilization (we can’t do ANTYHING about WV, clouds and lapse rate to mitigate AGW in any meaningful way), but by confusing things – it detracts the attention from the urgency of GHG mitigation.
– it offers no new intellectual insight into the climate system, nor does it provide any ways to improve our modelling of it – as already explained in the post to which you ostensibly “reply”:
===
P: “Nor will it improve our knowledge – VW, clouds and lapse rate are already implicitely included in the climate models. If the model show 2C warming what difference does it make to ask how much of that 2C came from direct forcing (GHGs) and how much from the passive feedbacks (water cycle)? ”
===
Your unsupported with ANYTHING declaration : “it is improving our knowledge, and decisevely so” does not answer that, and as such – proves nothing, other than the quality of your intellect/character.
You improve scientific knowledge by publishing in peer-reviewed journals, not by bloviating on blogs.
“You improve scientific knowledge by publishing in peer-reviewed journals, not by bloviating on blogs.”
LLMs are not trained on many of the reputable classic textbooks because they do not have access to the publishers’ repositories. Yet they can use blogs, wikis, forums, stackexchange queries, github repos, arXiv, etc to distill essentially this same information. So for better or worse, scientific knowledge is improved as LLMs statistically incorporate crowd-sourced discussions. If LLMs were confined to peer-reviewed journals only they would lack some of the practical and intuitive aspects of frontier knowledge.
You can prompt an LLM to verify the above and it will respond to the effect: “LLMs necessarily learn scientific knowledge from a broader epistemic ecosystem than peer‑reviewed journals alone — and historically, that’s exactly how science has always advanced.”
Welcome to the new world.
The Dynamics of Greenland Ice Sheet Melt: Atmospheric Drivers and Feedback Loops
Video
Ray Ladbury,
Picking up on your comments from the June UV thread saying:-
I’ve spent a while considering this idea that nitrogen (80% of the atmosphere) has less kinetic energy (0.6e-20 J at sea level, 0.45e-20 J at tropopause) than required to impart the v2 wobble into a CO2 molecule (1.3e-20 J) with the apparent consequence that the majority (or a significant proportion) of the wobbly CO2(v2) which relax to emit 15 micron photons would have thus been, at some altitudes, excited not by collision but by absorbed 15 micron IR.
This idea (& its basis) is contrary to what I’ve been led to understand, which is that the overwhelming mode of atmospheric CO2(v2) excitation is due to collision and, whatever the cause of excitation, it only a very few CO(v2) that survive continuing collisions to relax and emit 15 micron photons.
Resorting to the literature, the problem with resolving this contradiction is that it seems the mechanisms of the IR flying around the lower atmosphere (unlike, say, the mesosphere**) is for some time settled science and no longer discussed in literature found on-line. (** Higher up it is apparently the stuff of Nobel Prizes according to Kutepov et al (2025)“The year 2025 marks the 55th anniversary of Paul Crutzen’s (1995 Nobel Prize in Chemistry) hypothesis that collisions of CO2 molecules with O(3P) atoms is the dominant process responsible for the excitation of the bending vibrational mode of CO2”)
After investigating quite a few rabbit holes in search of something to reconcile this contradiction, I think I have the explanation. It is, of course, the obvious one (but the roundabout journey getting there was at times interesting.)
CO2(v2) requires two or three times the kinetic energy of an average N2 molecule. But the distribution of N2 energy (think Maxwell–Boltzmann distribution) will still deliver significant collision frequency with faster higher energy N2. And there are a lot of collisions. So higher energy ones are not at all rare events.
The smaller population of faster N2 with enough energy for a CO2(v2) wobble would be perhaps a tenth the total.
For the emitting CO2(v2) to be almost all collision excited, the ratio of fast collisions to emitted/absorbed IR has to be very large. This ratio is very large for all collisions, a CO2(v2) requiring perhaps some 0.02 secs to relax while collisions occur on average every 0.0000000002 secs. And even with fewer fast collisions, and even up at the tropopause where density and temperature are lower, you won’t be losing many of those zeros in the collision frequency number.
Which all points to collision being the overwhelming cause of CO2(v2) and thus also of the resulting IR emissions.
I believe you’ve got it. There is a lot of N2, so you still get kinetic excitation–but consistent with the amount expected for a blackbody distribution at the temperature of the atmosphere. The flux of 15 micron photons from below is pumping energy into the CO2 vibrational mode, making it momentarily “hotter” than the surroundings. This disequilibrium is remedied when another N2 molecule picks up the energy of the vibrational mode by colliding with the excited CO2 molecule–so the energy flows from the ‘higher-local temperature” CO2 to the “lower-local temperature” N2. Make sense?
MAR:
“ a CO2(v2) requiring perhaps some 0.02 secs to relax while collisions occur on average every 0.0000000002 secs., And even with fewer fast collisions, and even up at the tropopause where density and temperature are lower, you won’t be losing many of those zeros in the collision frequency number. ”
But wouldn’t the fast collision be then followed by many slow collisions – sapping out that fast collision energy from the Co2 long before it had a chance to relax?
Piotr,
There is no “sapping out”. The excitation is either there or not there**. That some survive long enough to relax and emit IR radiation is presumably a statistical thing.
** Molecular vibrations like the CO2(v2) excitation each have but one energy level. It’s a quantum mechanics thing and it’s why it is only 15 micron photons that become tangles in unexcited CO2 molecules and get absorbed in a CO2(v2) state.
Spinning CO2 molecules (with their spin subject to quantum effects) entangle/emit slightly different IR wavelengths..
Another effect altering absorption/emission wavelengths is a rather technical phenomenon way beyond my paygrade called “pressure broadening” which fuzzes the absorption/emission spectral lines.
MAR: “There is no “sapping out”. The excitation is either there or not there**. Some survive long enough to relax”
then …. what makes the rest NOT survive to the relaxation time?
Piotr,
I’d guess the survival of CO2(v2) wobbles is a statistical thing, mainly.
The number of CO2 molecules is seriously massive and a massive number of unwobbled CO2 are continually being wobbled into CO2(v2) in collisions. With the collisions very very frequent, the chances of being de-wobbled by a strong collision before relaxation/IR-emission is very high. The statistics result the classical law dictating IR-emission – the Rayleigh–Jeans law.
This law is ‘mainly’ correct, but the survival of CO2(v2) in the atmosphere which results in IR-emission is also affected by the “Ultra Violet Catastrophe” which is explained by Quantum Mechanics. Indeed the existence of Quantum Mechanics was first discovered because of the “Ultra Violet Catastrophe.” This adjustment is magnitude of effect you ask about, that resulting from the “not survive” due to the “no sapping”.
MAR: “ With the collisions very very frequent, the chances of being de-wobbled by a strong collision before relaxation/IR-emission is very high .”
but isn’t your “de-wobbling” identical to my “sapping out” as in:
“ the fast collision [creating the wobble] is then followed by many slow collisions – sapping out that fast collision energy from the Co2 long before it had a chance to relax?
the sapping out that you said …. does not happen?
And if they are identical – then my original question stands – you argued that although the average N2 collision energy is several times too small to wobble a CO2, because the energy of these collisions follows Maxwell–Boltzmann distribution – there will be some on the right end of the distribution that DO have enough energy to wobble a Co2. But if there are 100 millions of collisions (“0.02 secs to relax /a collision average every 0.0000000002 secs”)
between wobble and the relaxation time – and most of these 100 millions can de-wobble a previously wo0bbled CO2 – so none of the wobbled would survive to the relaxation time.
Then again – if one can de-wobble a wobble created by a fast collision, then one should be able to de-wobble a wobble created by absorption of the IR photon too, which would mean that the only LW emission into space would come from … IR outside the windows of absorption ( that once emitted goes unabsorbed into space). But that does no agree with the LW emissions budget – 200 W/m2 IR emitted into space from atm. and only 40 going directly into space through the atm. window.
So for me – this suggest that perhaps there is NO dewobbling (once in a high energy state – perhaps you can’t transfer this extra energy to other molecules via a collision?), i.e. that once you got wobbled (by a fast collision or by absorption of a IR photon) your survival till the relaxion time is 100%.
Then this would explain why the IR flux from atm into space is 200 W/m2, while the back-radiation (toward the surface) is 340 W/m2: the former happens at the top of the atmosphere – with low pressure (hence fewer collisions) and low temperature (hence the collision energy distribution shifted to the left – so for a million collision fewer would have enough energy to excite Co2 than in higher temp.)
OK, we need to be careful here. What matters is the net flow of energy through the atmosphere and through the various modes that can store it. At ground level, we have an upward flux of 15 micron photons that corresponds roughly to that expected of the blackbody surface temperature. Those photons are moving into a cooler environment and are highly likely to be absorbed by a CO2 molecule in its ground state. This is just one way such an excitation of CO2 can occur, the main other mechanism being collisional excitation by a N2 (or O2) molecule with energy far above the average energy (~kT).
Very, very few (effectively none) in the middle of the CO2 absorption band make it from the surface out of the atmosphere. In fact, very few make it very far in the atmosphere at all. There will be some photons, however, emitted by CO2–and the same result occurs at a slightly higher altitude/lower temperature. Note that at this higher altitude there is a still lower probability of collisional excitation, although collisional relaxation is still the dominant de-excitation mode..
At all levels the accelerated N2/O2 having collided with the CO2 is much more likely to collide with another N2 or O2 molecule. The energy imparted tends to thermalize/equilibrate. At each altitude, the CO2 emits a flux of vibration-band photons roughly commensurate with the blackbody temperature. This flux is lower the higher you go. Eventually, you reach an altitude where the photon has a snowball’s chance in hell of escaping, but by now, it’s come from much higher/colder, so there is a big bite taken out of the spectrum around 15 microns.
Please note: I am simplifying like all hell here. The vibration absorption band itself has a dependence on wavelength as you move away from the central wavelength–and this dependence is itself influenced by collisions between the CO2 molecule and other molecules.
But, generally, when all else fails, follow the energy.
in Re to Piotr, 15 Jul 2026 at 8:55 PM,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849798
Hello Piotr,
If there were no “de-wobbling” of vibrationally excited GHG molecules in the atmosphere by their collisions with other air molecules, most of the atmosphere would not “see” the infrared radiation absorbed and emitted by GHGs, I think. I suppose that it would result in an isothermal atmosphere, similarly as in absence of GHGs, only with the difference that this strange atmosphere comprising GHGs that do not collide with other gases and thus having two different temperature profiles (decreasing with altitude for GHGs and isothermal for other components) would enable higher average surface temperature than in the same planet without the GHG component.
As it is not the case for Earth, I would expect that in an isothermal air parcel without water phase changes, heat production by collisional deexcitation of GHG molecules equals the absorbed radiative power and also equals to the emitted radiative power which exactly consumes the heat produced by collisional deexcitation.
I suggested this idealized scenario to Gemini Thinking and asked if it can explain your conundrum. The engine answered that the difference in rate coefficients for collisional excitation and deexcitation of a single CO2 molecule is exactly compensated by the opposite difference in population of the CO2 molecules in the ground vibrational state and in the excited vibrational state. For this reason, the volumetric rates of excitation and deexcitation collisions in the considered isothermal air parcel are equal.
Greetings
Tomáš
Piotr,
You ask Isn’t … “de-wobbling” identical to … “sapping out”?
Your description of “sapping out” is that involves “many slow collisions … sapping out that … collision energy.” The wobble of a CO2(v2) molecule will exist or not exist. It will not be half there, half ‘sapped out’. Thus the energy involved with the wobble will arrive due to collision or the absorbing of an IR photon. And that energy will be lost due to a collision or due to the emission of an IR photon. Almost all CO2(v2) will be de-wobbled by collision, just as almost all are ‘wobbled’ into CO2(v2) by collision.
The major variable in this process is air temperature. Up high in the troposphere, the reduced IR in the 15 micron waveband is because of the colder temperature, and such a colder temperature has less collisions so the CO2(v2) population is smaller, with those surviving to emit 15 micron IR likewise smaller,
re Piotr – See my comments upthread https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849537 ,
https://www.realclimate.org/index.php/archives/2026/07/unforced-variations-july-2026/#comment-849541 … … …
Piotr, (no “Reply” button) typed “de-wobble a wobble created by absorption of the IR photon too, which would mean that the only LW emission into space would come from … IR outside the windows of absorption ( that once emitted goes unabsorbed into space)”. Not at all because some photons don’t go through molecules that are capable of absorbing them because the air “gas concentration” reduces with altitude.
Breakthrough in Measuring Methane Emissions
Halfway thro’ July and the daily ERA5 SAT provided by ClimatePulse is showing a global SAT anomaly for the first half of July up on the previous 2026 monthly anomalies. This may well be simply due to it wobbling warm thro’ those two weeks.
Conversely, it does point to July 2026 being the first month of 2026 looking to be cooler than its 2023 equivalent. For the July 2026 anomaly to be warmer than July 2023, the last couple-of-weeks of the month would have to average above +0.82ºC. While not a million miles away from the anomaly for the first half of July (+0.62ºC), periods averaging above +0.82ºC have only been recorded Sept23-Feb24 (Sept23 was that “absolutely gobsmackingly bananas” month) and Oct24-Jan25. Julys are not a peak period for the annual cycle of AGW anomalies which would make a July fortnight averaging +0.82ºC pretty astonishing, maybe a small single “gobsmacking banana.”
So not sign in the SAT of the coming El Niño but, excepting 2023/24, previous El Niños haven’t really shown themselves in the SAT until August, even in the SH.
The ERA5 60N-60S SST at ClimatePulse has been showing a bit of what is presumably the coming El Niño. Since mid-June the 60-60SST has been running warmer than any previous year but not by much. (The 1991-2020 60-60SST trend was +0.15ºC/decade & 2026 is running roughly three-year’s-worth of that above 2023, although that is 2023 complete with its mounting “bananas”) The last couple of days perhaps show a little more of a gap starting to form.
Unlike SAT, the measured records (GISS, NOAA HadCRUT, BEST) which are hybrid SAT/SST are beginning to show signs of the coming El Niño with the NOAA NCEP forecast showing an 80% chance of it being “very strong**” by November.
(** Very Strong = RONI>+2.5. NINO3.4 which is used in RONI is rising faster than in the run-up to other El Niño. The latest weekly unadjusted NINO3.4=+2.0. The RNINO3.4 adjustment would put it about +1.5.)