In a new GRL paper, Svensmark et al., claim that liquid water content in low clouds is reduced after Forbush decreases (FD), and for the most influential FD events, the liquid water content in the oceanic atmosphere can diminish by as much as 7%. In particular, they argue that there is a substantial decline in liquid water clouds, apparently tracking a declining flux of galactic cosmic rays (GCR), reaching a minimum days after the drop in GCR levels. The implication would be that GCR can affect climate through modulating the low-level cloudiness. The analysis is based on various remote sensing products.
The hypothesis is this: a rapid reduction in GCR, due to FD, results in reduced ionization of the atmosphere, and hence less cloud drops and liquid water in low clouds. Their analysis of various remote sensing products suggest that the opacitiy (measured in terms of the Angstrom exponent) due to aerosols reaches a minimum ~5 days after FD, and that there is a minimum in the cloud liquid water content (CWC)
minimum occurring ~7 days later than the FD. They also observe that the CWC minimum takes place ~4 days after the fine aerosol minimum (the numbers here don’t seem to add up).
The paper is based on a small selection of events and specific choice of events and bandwidths. The paper doesn’t provide any proof that GCR affect the low clouds– at best -, but can at most only give support to this hypothesis. There are still a lot of hurdles that remain before one can call it a proof.
One requirement for successful scientific progress in general, is that new explanations or proposed mechanisms must fit within the big picture, as well as being consistent with other observations. They must also be able to explain other relevant aspects. A thorough understanding of the broader subject is therefore often necessary to put the new pieces in the larger context. It’s typical of non-experts not to place their ideas in the context of the bigger picture.
If we look at the big picture, one immediate question is why it should take days for the alleged minimum in CWC to be visible? The lifetime of clouds is usually thought to be on the order of hours, and it is likely that most of the CWC has precipitated out or re-evaporated within a day after the cloud has formed.
In this context, the FD is supposed to suppress the formation of new cloud condensation nuclei (CCN), and the time lag of the response must reflect the life time of the clouds and the time it takes for new ultra-fine molecule clusters (tiny aerosols) to grow to CCN.
Next question is then, why the process, through which ultra-fine molecule clusters grow by an order of ~1000 to become CCN, takes place over several days while the clouds themselves have a shorter life time?
There is also a recent study in GRL (also a comment on May 1st, 2009 in Science) by Pierce and Adams on modeling CCN, which is directly relevant to Svensmark et al.‘s hypothesis, but not cited in their paper.
Pierce and Adams argue that the theory is not able to explain the growth from tiny molecule clusters to CCN. Thus, the work by Svensmark et al. is not very convincing if they do not discuss these issues, on which their hypothesis hinges, even if the paper by Pierce and Adams was too recent for being included in this paper.
But Svensmark et al. also fail to make reference to another relevant paper by Erlykin et al. (published January 2009), which argues that any effect on climate is more likely to be directly from solar activity rather than GCR, because the variations in GCR lag variations in temperature.
Furthermore, there are two recent papers in the Philosophical Transactions A of the Royal Society, ‘Enhancement of cloud formation by droplet charging‘ and ‘Discrimination between cosmic ray and solar irradiance effects on clouds, and evidence for geophysical modulation of cloud thickness‘, that are relevant for this study. Both support the notion that GCR may affect the cloudiness, but in different aspects to the way Svensmark et al. propose. The first of these studies focuses on time scales on the order of minutes and hours, rather than days. It is difficult to explain how the changes in the current densities taking place minutes to hours after solar storms may have a lasting effect of 4-9 days.
There are many micro-physical processes known to be involved in the low clouds, each affecting the cloud droplet spectra, CWC and the cloud life times. Such processes include collision & coalescence, mixing processes, winds, phase changes, heat transfer (e.g., diffusive and radiative), chemical reactions, precipitation, and effects from temperature. The ambient temperature determines the balance between the amount of liquid water and that of water vapour.
On a more technical side, the paper did not communicate well why 340 nm and 440 nm should the magic numbers for the remote sensing data and the Angstrom exponents, calculated from the Aerosol Robotic Network (AERONET). There are also measurements for other wavelengths, and Svensmark et al. do not explain why these particular choices are best for the type of aerosols they want to study.
For a real effect, one would expect to see a response in the whole chain of the CCN-formation, from the smallest to the largest aerosols. So, what about the particles of other sizes (or different Angstrom exponents) than those Svensmark et al. have examined? Are they affected in the same way, or is there a reason to believe that the particles grow in jumps and spurts?
If one looks long enough at a large set of data, it is often possible to discern patterns just by chance. For instance, ancient scholars thought they found meaningful patterns in the constellations of the stars on the sky. Svensmark et al. selected a smaller number of FDs than Kristjansson et al. (published in 2008) who found no clear effect of GCR on cloudiness.
Also, statistics based on only 26 data points or only 5 events as presented in the paper is bound to involve a great deal of uncertainty, especially in a noisy environment such as the atmosphere. It is important to ask: Could the similarities arise from pure coincidence?
Applying filtering to the data can sometimes bias the results. Svensmark et al. applied a Gaussian smooth with a width of 2 days and max 10 days to reduce fluctuations. But did it reduce the ‘right’ fluctuations? If the aerosols need days to form CCNs and hence clouds, wouldn’t there be an inherent time scale of several days? And is this accounted for in the Monte-Carlo simulations they carried out to investigate the confidence limits? By limiting the minimum to take place in the interval 0-20 days after FD, and defining the base reference to 15 to 5 days before FD, a lot is already given. How sensitive are the results to these choices? The paper does not explore this.
For a claimed ‘FD strength of 100 %’ (whatever that means) the change in cloud fraction was found to be on the order 4% +-2% which, they argue, is ‘slightly larger than the changes observed during a solar cycle’ of ~2%. This is not a very precise statement. And when the FD only is given in percentage, it’s difficult to check the consistency of the numbers. E.g. is there any consistency between the changes in the level of GCR between solar min and max and cloud fraction and during FD? And how does cloud fraction relate with CWC?
Svensmark et al. used the south pole neutron monitor to define the FD, with a cut-off rigidity at 0.06GV that also is sensitive to the low-energy particles from space. Higher energies are necessary for GCR to reach the lower latitudes on Earth, and the flux tends to diminish with higher energy. Hence, the south pole monitor is not necessarily a good indicator for higher-energy GCR that potentially may influence stratiform clouds in the low latitudes.
In their first figure, they show a composite of the 5 strongest FD events. But how robust are these results? Does an inclusion of the 13 strongest FD events or only the 3 leading events alter the picture?
Svensmark et al. claim that the results are statistically significant at the 5%-level, but for the quantitative comparison (their 2nd figure) of effect of the FD magnitude in each of the four data sets studied, it is clear that there is a strong scatter and that the data points do not lie neatly on a line. Thus, it looks as if the statistical test was biased, because the fit is not very impressive.
The GRL paper claims to focus on maritime clouds, but it is reasonable to question if this is true as the air moves some distance in 4-9 days (the time between the FD and the minimum in CWC) due to the winds. This may suggest that the initial ionization probably takes place over other regions than where the CWC minima are located 4—9 days afterward. It would be more convincing if the study accounted for the geographical patterns and the advection by the winds.
Does the width of the minimum peak reveal time scales associated with the clouds? The shape of the minimum suggests that some reduction starts shortly after the FD, which then reaches a minimum after several days. For some data, however, the reduction phase is slower, for others the recovery phase is slower. The width of the minimum is 7-12 days. Do these variations exhibit part of the uncertainty of the analysis, or is there some real information there?
The paper does not discuss the lack of trend in the GCR of moderate energy levels or which role GCR plays for climate change. They have done that before (see previous posts here, here, and here), and it’s wise to leave out statements which do not have scientific support. But it seems they look for ways to back up their older claim, and news report and the press release on their paper make the outrageous claim that GCR have been demonstrated to play an important role in recent global warming.
A recent analysis carried out by myself and Gavin, and published in JGR, compares the response to solar forcing between the GISS GCM (ER) and the observations. Our analysis suggests that the GCM provides a realistic response in terms of the global mean temperature – well within the bounds of uncertainty, as uncertainties are large when applying linear methods to analyse chaotic systems. The model does not include the GCR mechanism, and the general agreement between model and observations therefore is consistent with the effect of GCR on clouds being minor in terms of global warming.
As an aside to this issue, there has been some new developements regarding GCR, galaxy dynamics and our climate (see the commentary environmentalresearchweb.org) – discussed previously here.
409 Responses to "Still not convincing"
You’re wrong RodB: “Mark (113), et al, except that the magnitudes were for the most part determined from the observations, not the other way around.”
The magnitudes were taken originally from the first person to use a computer powerful enough to do the calculations: Gilbert Plass, in 1956.
Increasing CO2 alone produces about 6C warming per doubling.
A GCM produces less than that because it includes cloud feedbacks and a change in the adiabatic lapse rate which Plass’s computer wasn’t designed to answer. It was designed to answer just “Does the effect of CO2 plateau because of Beers Law operating?” and the answer was “no”.
I admire Svensmark for his creativity and willingness to test new theories that go against the grain. Scientists willing to work against the dominant paradigm ensure that science progresses even when the masses might happen to be partly or wholly incorrect. I also think that the correlation between cosmic rays and cloudiness (and to a lesser extent, that between solar cycle length and temperature when the right averaging length is applied) is just compelling enough for me to reserve an ounce of skepticism regarding the *magnitude* of anthropogenically-induced global warming, which I consider to be theoretically obvious (how could absorption and re-emission of terrestrial radiation but transmission of solar radiation possibly not cause at least some degree of warming?). The recent 2003-2008 temperature drop could have been due to La Nina alone, or perhaps to some combination of factors that included the low solar activity, if the amplification mechanisms are true. The arguments against his theory are, in my mind, no more convincing than his arguments in its support. I remain undecided and unconvinced. However, the following is certain. The fact that the transient July 2009 upward spike in mean global, satellite-induced temperature is approaching record territory *despite the lull in solar activity and the presumed increase in cosmic ray intensity* does NOT work in his favour. The satellite trend is really starting to look more and more like continued AGW warming with noise introduced by oceanic effects! I’m nearly back to being pro-AGW… but I’m a born skeptic.
Barton Paul Levenson says
George Tobin writes:
The latest evidence is that cloud feedback is positive:
Clement, A.C., Burgman R., and J.R. Norris 2009. “Observational and Model Evidence for Positive Low-Level Cloud Feedback.” Science 325, 460-464.
So cloud feedback can’t save the denialists after all.
Ray Ladbury says
Lulo says of Svensmark: “The arguments against his theory are, in my mind, no more convincing than his arguments in its support.”
Well, other than the fact that GCR fluxes have not changed appreciably in 60 years–precisely the period when we saw the greatest warming. Oh, and then there’s the fact that he doesn’t have a convincing mechanism. Now maybe, just maybe there’s an effect there. It’s very interesting if there is. It just won’t save our sorry asses.
J. Bob says
114 – SecularAnimist – And GE is not putting out their own AGW agenda?
127 – Mark – How many aero engineers do you know? Having been involved with these engineers in modeling and designing helicopter blades, on hybrid and digital computers, we were all aware bees could fly. According to one aero drag equation, drag increases to infinity at Mach 1, but bullets didn’t have a problem breaking the sound barrier. We also were aware of that.
Richard Steckis says
Ray Ladbury says:
“Oh, and then there’s the fact that he doesn’t have a convincing mechanism. Now maybe, just maybe there’s an effect there. It’s very interesting if there is. It just won’t save our sorry asses.”
In the normal progression of science the next step will be to find the mechanism. Have you read the paper? Does he not address the supposed issue of unchanging GCR flux? Here we have a scientist who is developing a possible theory on the influence of GCRs on climate. Each step builds on the last and each step may lead to an explanation or to a dead end. That’s real science.
BPL – “The latest evidence is that cloud feedback is positive:”
The Clement et. al. paper is no slam dunk so I wouldn’t hang my shingle on it.
Rod B says
Dhogaza (146+), I don’t necessarily fully agree, but your answers to my publishing questions have some basis.
I don’t remember any muff dive or boot licking; I don’t even know what an earth bow is. I did not express any “appreciation” in the grand sense.
You answered, “No. AGW theory isn’t based on CO2 combusting” which is probably accurate (or maybe not..??) but has no relevance to my question.
You said, “Nothing skeptical in that comment” which proves my assertion that reading with eyes open is better.
You ask, “Then why doesn’t he even begin to discuss the carbon cycle?” It might be more complete in the full study, but the abstract does hint at that all too briefly and loosely.
His conclusion that CO2 lifetimes are likely considerably shorter than generally assumed is based in part on observation and supported by numerous other studies (which I can’t verify), and by uncertainties expressed by the IPCC. I think that is deserving of further thought and analysis despite it countering the AGW dogma. His further conclusion on the direct effect on AGW is short on credibility.
I’ve said thousands of times that I do believe in the holocaust.
Rod B says
Mark, other than one can not prove a negative by definition…
I will now claim that the Sun will rise in the NNE 100 years from now. Either accept that or prove I’m wrong. The onus is yours.
Robert Bateman says
Denialists are not going to cross your eyes and dot your t’s if you step out into the public and start telling them that clouds are going to boil the seas and fry the land. Everyday people are likely to cause you bodily harm after their intelligence has been insulted, given the misery that the last “we must act quickly” call has caused them.
Don’t try that in the local bar. Really.
Forget about the denialists being saved.
The public is growing largely denialist as they think you are tyring to pull the wool over thier eyes.
And they are growing agitated over the 24/7 media blitz that every weather event is Global Warming.
Take the public litmus test, if you don’t believe me.
They react just as badly to warnings of Deep Solar Minimum.
They don’t want to hear it any more.
Good thing climate science makes no such claims, then.
Or perhaps because they’re being lied to about climate science, just as you did above …
The observed warming from the observed anthropogenic increase in CO2 is already “significant”.
Indeed, the observed warming from the observed anthropogenic increase in CO2 is already “alarming”.
Your hypothetical Denier doesn’t merely need to support his assertion that warming “will not be significant” — he needs to explain what he thinks is going to reverse the significant warming that has already occurred, which is already having dangerous effects on the Earth’s climate, hydrosphere, cryosphere and biosphere.
Robert Bateman wrote: “Everyday people are likely to cause you bodily harm after their intelligence has been insulted, given the misery that the last ‘we must act quickly’ call has caused them.”
What in the world are you babbling about? What “call”? What “misery”? What “insult”?
What a lot of nonsense.
If you have something to say, please say it, and desist with the too-clever cutesy obscurities.
And why should anyone give the slightest credence to your assessments of public opinion?
Doug Bostrom says
Robert Bateman 6 August 2009 at 11:38 AM
The picture you paint sounds akin to some of the uglier phases of human history, such as the later period of the English Reformation. Certainly today we’ve got some unholy alliances in play featuring the deepest forms of cynicism exploiting the gullible in order to preserve the existing arrangement of cash flow, a feature in common with parts of the Reformation.
Your dark imaginings of bar brawls and an agitated publics’ strained patience on the verge of erupting into flames are something entirely new for me to read here. By any chance, are you yourself harboring deep resentment verging on violence, and if so why?
We live in a time when rhetoric found in our mass media is flirting with monstrous impulses, again in order to preserve the status quo. One needs to be very careful not to end up as a foolish foot soldier; the authenticity of one’s state of mind is worth pondering.
J. Bob wrote: “And GE is not putting out their own AGW agenda?”
No, in fact, General Electric is not propagandizing the public about the reality of anthropogenic global warming. They are certainly not spending many tens of millions of dollars to fund propaganda mills disguised as “conservative” think-tanks to deliberately and elaborately deceive the public with blatant lies and phony-baloney pseudoscience, as ExxonMobil has done for decades and continues to do to this day.
What General Electric is doing — along with Intel, Google and plenty of other corporations — is recognizing that there is plenty of money to be made from the clean energy, efficiency and smart-grid technologies that will drive the post-fossil-fuel, new industrial revolution of the 21st century. And they are aggressively working to be part of that revolution and make a lot of money from doing so.
Fossil fuels are the past. Clean energy is the future. Cast your lot where you will. ExxonMobil’s strategy of obstruction and delay won’t work forever. Their obsolescence is inevitable.
with respect to your comment (my italics):
It sounds like you’re praising the paper without having read it Richard! We can answer your question “Does he not address the supposed issue of unchanging GCR flux?” , with a straightforward “no, he does not address the issue of unchanging GCR flux, which, by the way , is not “supposed””. It’s a simple answer. He doesn’t address that question. The unchanging GCR flux (since 1950) is real and not “supposed”:
So there’s no influence of GCR on climate with respect the period of very marked warming of the last 30-odd years. We can extend the absence of evidence of a GCR effect on climate back through the last 1000 years.
It would be unfortunate if we were taken in by nonsense in press releases and on dodgy web sites, when the putative “CRF-climate link” is irrelevant to our present circumstances, however interesting it might be to study this…
Hank Roberts says
For Robert Bateman, you wrote
> clouds are going to boil the seas and fry the land …
> their intelligence has been insulted …
> misery that … “we must act quickly” call has caused …
> they think you are tyring to pull the wool over thier eyes.
> … the 24/7 media blitz that every weather event
> is Global Warming.
See, the serious posters here object to that crap just as much as the folks up in the mountains with their shotguns.
There’s no limit to nitwittery and it shows up out at the edges of every political dimension.
But ask yourself — where did you read all these claims?
Earlier you posted that you’d heard [somewhere] that RC censored everyone but scientists something-or-other.
That was wrong, as you said you’ve found from your own experience.
So — What sources are you relying on?
And why do you trust them?
This is a serious question. There is a whole lot of bad information, a whole lot of PR spin, and very few people who both understand the science and try to explain it even-handedly.
Some of those folks are available here. You can read their publications in the sidebar, in the science journals.
_Most_ of us here are just readers like yourself, no more to be relied on than any other guy in a bar until they’ve established some track record for reliability at honestly reading and discussing the science.
Remember — if you write polemics that attract flamers and net-wits, they’ll show up here. They aren’t ‘censored’ either, not til they prove themselves consistently useless.
So — think about where you were getting your information.
Question _every_ source and look for primary references.
This will help.
Patrick 027 says
Re Rod B. (although I went off on a tanget here that applies to some others more than you):
“Mark, other than one can not prove a negative by definition…”
What’s a negative and a positive here? A numerical predicted relationship based on paleo-evidence for that relationship and laws of physics
(PS as a system of equations to be solved, it is in some respects overdetermined – fewer variables than equations, unless we get too specific in our predictions (by predicting many dimensions) – of course with so many constraining relationships and so many possible variables to solve, such neat categorizations get a bit blury, so we end up with ranges of uncertainties rather than overdetermined vs underdetermined vs… and of course some contraints are actually inequalities… so never mind)
could be ‘falsified’ in varying amounts with two different signs possible for each dimension, and in fact some error is expected (for example, our best prediction might be 3.00 deg C per doubling of CO2 from 300 to 600 ppm given the present arrangements of continents and ice sheets and extant species etc., but we might also predict with large confidence that it will not be 3.00 deg C exactly).
The existence of any relationship – a boolean quantity – could be falsified out right but of course the mere existence of a relationship was long ago made almost necessary by basic physics – the only way out of it is some very precise counteracting mechanism that has yet to be discovered and this appears to be falsified by mountains of data.
“I will now claim that the Sun will rise in the NNE 100 years from now. Either accept that or prove I’m wrong. The onus is yours.”
Depends on latitude. With precession being quite slow with respect to 100 years, 100 years from *now* will be on the Northern Hemisphere summer side of the equinoxes, so the sun will rise north of east and set north of east everywhere that it rises and sets, but in many places this will be NE or ENE; at some latitudes NNE, at one latitude the sun could be said to rise and set in the same instant at due N, and north of that latitude the sun will neither rise nor set for a range of days centered about the Northern Hemisphere summer solstice.
That is of course a prediction that depends on several assumptions, including that most of us are not hallucinating most of the time, that what we have identified so far as the laws of physics are indeed laws of physics and not some 13-billions-year coincidental correlation that will stop soon, etc, and on the less esoteric side, that the Earth is not struck by some very large asteroid able to change rotation, tilt, and trajectory significantly, etc…
PS to whoever asked about science and burden of proof: Relationship of CO2 to temperature without feedbacks besides blackbody radiation feedback already firmly established, would feel comfortable betting life’s work on it.
Some immediate feedbacks established to varying degrees.
Thus the burden of proof mainly rests mainly with any claims that either shift the climate sensitivity in either direction from where it is now thought to be, or narrow the range of uncertainty from where it now stands.
And so on for what climate change means to ecosystems, economies, etc.
PS somewhere above I think someone implied that a dry adiabatic lapse rate would have T inversely proportional to p as in the ideal gas law for constant V – but V is not constant; the actual relationship is harder to derive because an adiabatic lapse rate has constant s (specific entropy), while v, p, and T change; the relationship is T/T0 = (p/p0)^exponent, where I believe (off the top of my head, here) ‘exponent’ is R/cp, (ratio of ideal gas constant to specific heat at constant pressure, the later being the coefficient of temperature in the formula for enthalpy (internal energy is cv*T, enthalpy is cp*T, the difference is the work done by expansion at pressure p; cp = R + cv for ideal gas). (T0 is the temperature at p = p0, and for p0 = 1000 mb, T0 = ‘theta’ = potential temperature).
An adiabatic process is isentropic (constant entropy) and thus is reversable. A moist adiabatic process is also isentropic and reversable when the entropy is that of the entire parcel of air including all phases of water, so long as their is no mixing or sorting – it ceases to be adiabatic upon precipitation (removal of water from the air), upon evaporation from water that was not part of the air before (from precipitation from other air or from wet surface), or when two air masses of different properties are mixed.
Barton Paul Levenson says
WHAT correlation? Take a look here:
Barton Paul Levenson says
Robert Bateman writes:
And what relevance does ANY of that have to whether AGW is really happening or not? “I am losing interest in this” cannot by any logical means lead to “This is not true.”
Peter Wilson says
oops.. I posted this in the wrong place: It ought to be here Not being an advocate of either the anthropogenic or the sceptic side, as I think both need to formulate convincing methodologies and experiments, there’s a lot of talk about the discovery of the heat trapping properties of c02, which supposedly is the ancestry of the modern consensus. However, in trawling the internet on “19th century c02 science”, I also came across this. The Woods experiment
Doug Bostrom says
Peter Wilson 6 August 2009 at 4:13 PM
The Roof Only Limits Loss.
If you keep looking you’ll find opinion blogs with an ignorance level way beyond “Woods proves there’s no such thing as global warming”. At some point you’ll come up against howlers such as “the 2nd law of thermodynamics proves there’s no such thing as global warming”.
Peter Wilson says
I’m only interested in the bandwiths of c02 and their saturation point. If for example two equal chambers were subject to the same temperature of 30C for the same duration such as half an hour, one containing 380ppm of c02 and the other 600ppm, the chamber with 380ppm should, under present climate theory, remain at around 30C whereas the one with 600ppm should reach a temperature of 34C, since the notion says that extra c02 increases temperature. The question is: Where does the extra 4C come from, given that the sourse of radiation is fixed at 30C?
[Response: This is rather confused I’m afraid. There is a good description of the greenhouse effect at Wikipedia. Read that and then come back if you still find something confusing. In your example you have confused the concepts of ‘temperature’ and ‘radiation’. – gavin]
You do realise that the term “greenhouse effect” is a metaphor, right? It doesn’t mean that the atmosphere is actually a greenhouse – there isn’t a big layer of glass all around the planet.
Have a look at this to see the difference between a greenhouse and the atmosphere.
Patrick 027 says
Re 170 – kudos to you for not ‘choosing’ before you know more. To help you know more:
I don’t know exactly what the Woods experiment is, but to cover the bases:
1. ‘greenhouse effect’: the basic idea is that when energy going into and leaving a system is of two different forms, the properties of a system can affect the energy inflow and energy outflow differently; for a greenhouse effect, the energy outflow is a loss of heat energy from the system in some way – radiative, convective, or conduction, or some combination. Depending on specifics, heat tends to flow spontaneously from higher to lower temperature (specifically, this is the ‘net’ flow of ‘heat’ energy), and in some way proportional to the difference in temperatures. If the energy inflow that adds heat the system is different than the heat outflow, the system must be gaining or losing ‘heat’ energy, and outside of phase changes and chemical reactions (or in extreme circumstances, nuclear), this tends to result in a change in temperature, which will tend to change the heat outflow to reduce the imbalance in energy fluxes. Thus, if the properties of the system are changed to reduce the loss of heat for a given temperature distribution, then the temperature will tend to rise within the system until balance is restored between the energy fluxes.
In the broad manner,
putting on a coat in the winter to stay warm (reduces conduction and convection (including perspiration), and radiation, from the skin to the cold air for a given temperature difference, so that the same metabolic rate and blood flow will result in a higher equilibrium skin temperature),
using a greenhouse (allowing a large fraction of solar energy in but inhibiting convection out (and maybe radiation, or not – depending on glass properties, perhaps?),
adding CO2 to the atmosphere (increasing optical thickness with greatest effect in a range of wavelengths between about 12 and 18 microns, so that the cooler upper layers of the troposphere become more visible from above at the expense of the visibility of the warmer surface below, and the cold darkness of space is less visible from all levels within the atmosphere and at the surface, so that for the same temperature distribution over height, there is a reduced net upward longwave radiant flux, so that the troposphere and surface system as a whole will tend to gain ‘heat’ energy – PS stratospheric cooling occurs at the same time because it recieves less radiation from below and also radiates more strongly to space due to increased visibility (which comes at the expense of the visibility of the layers below as seen from above)
these all follow the same pattern and the term ‘greenhouse effect’ makes sense even though there are differences among the phenomena.
With notable variations over latitude, time of day, time of year, etc, the general tendency is for radiative forcing by itself to make the surface+lower atmosphere unstable to convection; thus, convection occurs (not everywhere at all times, but heat energy is stored over time, and heat transported vertically can also move horizontally – air at high latitudes may carry heat from lower latitudes that came from the surface at lower latitudes). Air expands and cools as it rises to levels of lower pressure (dry adiabatic lapse rate)- less rapidly if water vapor is condensing due to release of latent heat (moist adiabatic lapse rate). Thus, when the air temperature decreases with height faster than the dry adiabatic lapse rate, the air overturns, and this happens so effectively that no such ‘superadiabatic lapse rates’ occur on large scales – they can be found in particular at the surface in the daytime (or over a warm ocean current with cold air blowing over it, etc.) because the surface slows convection (air has to stop in the vertical direction and spread or contract horizontally). Convection tends to maintain a lapse rate that is of neutral stability – within the troposphere, this tends to be a moist adiabatic lapse rate (except below cloud bases, where that applies) because water vapor evaporates from the surface and condenses and precipitates. Convection cannot penetrate to any and all levels of the atmosphere (because of cooling with height) and certainly cannot carry significant energy into space; ultimately the heat energy escaping to space must be almost entirely in the form of radiation. Convection does couple the various vertical levels of the the troposphere and surface so that the temperature at all vertical levels tend to shift together in response to changes in net radiative heating of the whole surface-troposphere system (which is proportional to the radiative forcing at the tropopause level) – although the rate and structure of convection may change depending on exactly how the radiative heating/cooling is distributed within the system. There are some latitudinal, regional, seasonal, and diurnal variations, etc, in this pattern, due to patterns of atmospheric circulation and feedbacks – for the present climate state, in any global warming forced by something not too idiosyncratic (so that the similarities in feedbacks are more important), the general tendency is for the mid-to-upper troposphere to warm more than the surface in the lowert latitudes due to the decrease in the moist adiabatic lapse rate with an increase in temperature (because the saturation water vapor pressure is roughly exponentially proportional to temperature, so at saturation (as in a cloud), there is more condensation per unit decrease in temperature at higher temperatures); at higher latitudes, the air tends to be more stable to convection because the air is heated from horizontal convection from lower latitudes – this is especially true in winter – and the snow-ice albedo feedbacks occur at surface level, so the greatest warming within the troposphere at higher latitudes tends to be near the surface, and the greatest warming is also in winter (though the seasonal timing mechanism is complicated – summer sea ice loss allows greater storage of solar heat in the water but without much temperature increase – the temperature increase occurs in the cold season because the water has to lose more heat before freezing can occur).
You may have heard that the CO2 radiative effect is saturated. It is true that, at any given wavelength, except when temperature variations are over shorter distances, adding the same additional longwave optical thickness has a decreasing effect on net longwave fluxes when the starting opacity is greater. The effect of additional CO2 is less than it would be if there were less CO2 to start with, or less cloud cover (especially high cloud cover) or less water vapor (especially upper tropopsheric water vapor) (PS I’d expect CO2-water vapor overlap has a smaller effect on additional CO2 for tropopause level radiation than for the surface, because water vapor is concentrated near the surface). However, there is some small but nonzero opacity for CO2 outside the 12 to 18 micron band. The general tendency is for the range of wavelengths of significant CO2 opacity to expand in proportion to the logarithm of the CO2 amount.
J. Bob says
“And they are aggressively working to be part of that revolution and make a lot of money from doing so.” Sounds like evil Exxon, only they (GE, etc.) are formulating a revolution.
GE is like any other company, they want to make profits. Do you think that GE does not have a vested interest in wind turbines, power generators, nuclear reactors, etc. and is lily white? Check your pension fund, it may have significant shares of Exxon, BP, Chevron, Marathon, etc. Why? Because they pay good dividends to retired teachers firemen, police, retired government employees. That’s where a significant amount of their profit goes.
Rod B says
Patrick 027 (167), We’re talking of proving a negative concept, not that one mathematical part of the concept is incorrect. If I claimed the rise per doubling is NOT 3 degrees +/-, then that burden of a “negative” proof would be mine. But in maintaining the logic I would actually have to prove another positive, like say the rise is 2.4 degrees +/- to “disprove” the 3 degree rise. A concept doesn’t require numbers. We skeptics are being asked to prove that AGW kinda in its entirety is not and never will happen. That can not be done. It does not matter if the argument/evidence for AGW is zero or infinite. Like you can’t prove that the sun will NOT rise on the NNE horizon.
There are however where the charge is over a specific piece. In the example where the theory is unassailably shown. e.g. CO2 absorbs IR radiation to some degree, the onus is back on me to prove that it doesn’t, if I so claim. But in areas of specificity where it is not unassailably shown (the solid belief by some in it not withstanding). e.g. the specific degree of IR radiation by CO2 in certain circumstances, I would retain some burden of evidence or proof of its negative. But, lacking that, could reject and would not have to accept (and would be scientifically correct) the positive premise until it is finally shown to be unassailably correct.
This was much simpler when I was sparring with Mark! ;-)
Interesting post. (yours!)
Peter Wilson says
I’m not disputing the logic of the observations, Patrick. The way laymen like me understand the climate is that shortwave heat from the sun hits the earth, landmass, oceans and then longwave re-radiation leaves the earth and gets progressively cooler on its upward/outward transit. Some of this is intercepted and re-transmitted by c02 then heads back into the atmosphere, oceans, landmass etc.
Here’s where it gets tricky for me. In order for the hypothesis to be valid, the 3rd point of heat transfer – the greenhouse effect – would have to be at least as warm as ground based temperatures in order to cause global warming, or to increase the temperature above what it would be if there was less co2. yet surely optimum temperatures are already achieved from incoing shortwave radiation..
Kevin McKinney says
Peter, the Woods experiment is irrelevant to the AGW hypothesis because the actual mechanisms are different in each case. A physical greenhouse works by confining the air heated by the solar radiation; the atmospheric “greenhouse effect” works essentially by raising the effective altitude (and hence lowering the temperature) from the atmospheric layer which radiates IR to space. Simplified, the CO2 slows down the rate of cooling.
In your thought experiment you don’t characterize the “radiation” to which each is subjected, nor the chamber walls. But if the radiation were IR of the correct frequencies, and if the chamber walls were transparent to that IR, then the 600 ppm chamber would indeed warm faster. Note however that the characterization of the radiation is not specified in degrees!
But your two chambers would cool equally well from a given temperature, I think, because the cooling rate is going to be determined mostly by the chamber walls, not the gaseous content. And if they were both subjected to 30C temperature–*not* the same as radiation, as Gavin says!–for long enough, they would both end up at 30C. Period.
(You could “subject them to the same temperature” by, say, placing the chambers in a bath held at precisely 30C. Heat would then be transferred by conduction, not radiation.)
Peter Wilson says
in other words – i’m still trying to understand where the increase in temperature from more c02 comes from. I accept there’s a greenhouse effect – just not sure where increasing temperatures from this greenhouse effect takes place.
Patrick 027 says
Rod B – “A concept doesn’t require numbers. We skeptics are being asked to prove that AGW kinda in its entirety is not and never will happen.”
Well, not quite. There is much evidence to back up the mainstream/consensus positions on AGW. It cannot be proven in a mathematical/philosophical sense – what can (besides math and logic itself ??- or not)?
The ‘skeptics’ we seem to be dealing with are not simply saying – “well, that’s where the science is now, but it could change, though we shouldn’t bet on it” – instead, they are making claims that either we can bet a lot on the slim possibilities and expect all to be okay, or that the current understanding in the mainstream *IS* wrong – with evidence and/or theory that is either: 1. part of the same that actually supports AGW (for example, evidence that constrains climate sensitivity to being between 0 and 6 deg C per doubling CO2 does not at all conflict with other evidence that constrains climate sensitivity to being between 2 and 4 deg C per doubling CO2; for 100 different groupings of evidence that each have a 5 % chance of being misinterpreted or erroneous, we can expect that some of those groupings would not by themselves lead to the correct answer; etc.), or 2. wrong – mistaken, based on some poorly written document that is easily recognizable as such, drawn from thin air, from whole cloth, or in violation of the laws of physics that are firmly established (claims that AGW violates the laws of thermodynamics generally require violations of those same laws).
Patrick 027 says
“*IS* wrong ”
and furthermore, is wrong in one particular direction.
Justin Anderson says
Proof? Isn’t this a question about evidence and the weight of it? Tell me one thing that is proven. Probabilities are everything.
Philip Petch says
Hank Roberts, some Greek hydrologists had a go at validating a range of climate models. See “On the credibility of climate predictions”, D. KOUTSOYIANNIS, A. EFSTRATIADIS, N. MAMASSIS & A. CHRISTOFIDES, Hydrological Sciences–Journal–des Sciences Hydrologiques, 53(4) August 2008…..
Barton Paul Levenson says
Peter Wilson writes:
This is the “back-radiation violates the second law of thermodynamics argument.” It’s based on a misconception. Check here:
Bart Declercq says
@180 Peter Wilson:
It is really rather simple: Sunlight comes down to earth in UV and Visible spectrum, gets absorbed by the ground & the water. The consequence of this absorption is that these items heat up. Heating up produces infrared radiation which is sent back up.
However, while CO2 is transparant to visible light and lets it through, it absorbs infrared radiation.
So the energy from the sun comes down onto the planet, but cannot get out again –> this is where the warming comes from.
In the experiment with the two chambers, if you put a lamp emitting visible light outside the chamber, and a dark object inside the chamber, then that object will absorb the light, then re-emit it as infrared light. If the chamber contains more CO2, more infrared will be absorbed by the gas in the chamber and it will heat up more than if it contained less CO2.
This is essentially an experiment which could be done in the 19th century and which is the basis of the concept of the “Greenhouse effect”
Kevin McKinney says
Peter, the key concept you are looking for, I think, is the idea of the energy budget. (This is the part of the science that goes back to Fourier, ca. 1824.)
Consider Earth and its atmosphere as one big system. When the system is in equilibrium, the energy coming in from the sun will equal the energy radiated away in all directions into space from the “top of the atmosphere” (TOA).
The greenhouse effect works by affecting the cooling rate of this system. With higher concentrations of greenhouse gases, IR is effectively emitted from higher (=cooler) altitudes. Since cooler temperature means lower rates of emission, the outgoing IR energy is now a bit less than the incoming shortwave energy–currently, by about .9 Watts per meter squared. Over time, this extra energy warms the overall system, raising emission rates again, and eventually bringing the system back into equilibrium at a slightly higher temperature. An elegant feedback loop.
This is highly simplified but I hope the real experts here will correct anything that’s too misleading in this brief explanation. I hope, too, that it helps!
Kevin McKinney says
Barton, nice explanation, as always.
It occurs to me that maybe J & J learned their thermodynamics from Flanders & Swan. You know,
“Heat won’t pass from a cooler to a hotter.
You can try it if you like but you’d far better notter.”
Ray Ladbury says
Rod B., your entire argument is predicated on the proposition that if you express your doubts sufficiently vaguely (e.g. “the specific degree of IR radiation by CO2 in certain circumstances,”), then there is no way you can be shown to be wrong. The thing is that there are worse things than being wrong. Wrong can be corrected. That is why Pauli said of one particularly confused paper, “This is so bad, it’s not even wrong!” Being wrong at least takes the courage to take a position. Being vague is simply cowardly.
Kevin McKinney says
WRT my earlier comment: For those readers who have not yet reached a certain age, you can hear Flanders & Swan on thermodynamics here.
J. Bob wrote: “GE is like any other company, they want to make profits. Do you think that GE does not have a vested interest in wind turbines, power generators, nuclear reactors, etc. and is lily white?”
I have no problem with either GE or ExxonMobil wanting to make profits. And certainly General Electric has engaged in and continues to engage in industrial practices that are environmentally harmful — the massive pollution of the Hudson River being a good example, and a case in which GE did in fact engage in a campaign of denialist propaganda in an ultimately unsuccessful attempt to avoid being held to account for the cost of cleanup.
However, it so happens that among GE’s business interests are some — wind turbines, energy efficiency and smart grid technologies, for example — that are among the key solutions to the problem of reducing the CO2 emissions responsible for anthropogenic global warming. If GE can turn a profit while helping to avert catastrophic climate change, more power to them.
However, you specifically asked “And GE is not putting out their own AGW agenda?” — implying that GE has engaged in a campaign of deliberately, elaborately deceitful propaganda to frighten the public with exaggerated fears of global warming, comparable to ExxonMobil’s generation-long campaign of denialism and obstruction.
And the answer is no. There is no evidence that GE has done any such thing. On the other hand there is a voluminous record of ExxonMobil’s multi-million-dollar campaign of deceit, their funding of denialist pseudoscience from cranks and frauds and other denizens of phony “think tanks”, and on and on.
This idea that global warming is not only a “hoax” perpetrated by “liberals” and “environmentalists” in concert with hundreds of climate scientists and dozens of major scientific organizations from all over the world, but is actually being funded and directed by General Electric and other clean energy manufacturers, seems to be the latest meme popular with the pseudo-ideological Ditto-Head denialist echo chamber — and it’s about the most absurd conspiracy theory I’ve heard yet.
Rod B says
Patrick (181), Evidence has a sliding scale. So what they “know”, or more accurately the degree to which they know also has a sliding scale. The burden of proof also varies between the arguing parties and is probably different for every specific aspect of AGW theory. the more complete the evidence the more the burden falls on the skeptic; the less complete the evidence the more the burden falls on the supporters — even if that evidence is none-the-less based on reasonable science.
My example is my claim that the evidence for a specific (within a narow range) temp increase per a doubling of CO2 at higher baseline concentrations is far from complete, even though it is based on a reasonable scientific projection. Now it would be neato if I could prove my contention. But I don’t have $millions of dollars of lab equipment, access to high-level libraries, or $millions of dollars for nor access to supercomputers. That does not make the supporters correct by default. As long as I’m not just flailing randomly, my contention is proper. In the general case. until the evidence is ironclad there is uncertainty on a sliding scale ranging from insignificant to monumental; making that evidence ironclad is primarily the onus of the supporters.
epilog: to head off a strawman argument that usually comes now, none of the above suggests that the supporters need to abandon their current position. They have to go with their best estimate and should not alter their position because Rod B has a problem. On the other hand they should not lose sight of the uncertainty and continue to work on it while simultaneously pushing what they currently think.
Rod B says
Ray (189), that’s just plain unfair (O.K. Wrong.) My example statement was crafted to be more specific (while still not taking a whole page), not vague. It was an attempt to confine my example to a specific area so others don’t try to deflect my assertion by arguing against a more general point that I didn’t make. Though I’m partly at fault as I intended to say, ” the specific degree of IR radiation absorption by CO2 in certain circumstances” — could’ve have been confusing.
Rod B says
Peter Wilson (180), I don’t know if you are looking the this basic level or not, but:
1) Infrared radiation emits from the earth surface, going the only direction it can — up, and cooling the surface in the process.
2) CO2 (or other GHGs) absorb some of that IR radiation. As this IR energy is stored in a molecule’s “internal energy”, this does not increase the temperature of the atmosphere.
3) The CO2 molecule then collides with another molecule (most likely O2 or N2) and transfers its internal energy to translation energy of the collidee. Translation energy is the energy of the whole molecule zipping through space and is the 1/2MV^2 that determines temperature. Ergo the O2/N2 molecules have a higher temperature. Ergo so goes the atmosphere.
4) The option other than collision is the CO2 emits IR radiation like that (but not the same — different photon) it absorbed. If it radiates upward and (let’s say) escapes the atmosphere the only total effect is the initial cooling of the surface; the temp of the atmosphere does not change. If it radiates downward and (let’s say) hits the surface, the surface is re-warmed; the temp of the atmosphere still does not change.
There’s a lot of other stuff going on that others have addressed here, but this is the basics.
Ray Ladbury says
Rod B. says, “It was an attempt to confine my example to a specific area so others don’t try to deflect my assertion by arguing against a more general point that I didn’t make.”
Except you don’t specify the conditions, the degree, or anything else that would be needed to address your contention that there is any significant degree of uncertainty about how CO2 behaves in an atmosphere. If you want to learn, you can’t be afraid of being wrong. You can’t be afraid to have others take issue with you. If they misunderstand then add detail and refine your expression. Vagueness is the enemy of understanding.
Doug Bostrom says
Rod B 7 August 2009 at 10:29 AM
May I suggest that once you’ve narrowed your point of inquiry to the point where it is sufficiently constrained as to be amenable to numeric analysis using uncontroversial facts, uncertainty may be reduced to relative insignificance?
Regarding “…evidence for a specific (within a narow range) temp increase per a doubling of CO2 at higher baseline concentrations is far from complete…”, perhaps it would be helpful to look at the subject through a slightly different prism and identify which real-world factors you believe would render numeric predictions less reliable. These could probably be prioritized as to the level of uncertainty they introduce. This approach has the advantage of showing a way forward in reducing uncertainty, and might also eliminate some redundant discovery effort.
Patrick 027 says
RE 194 – “As this IR energy is stored in a molecule’s “internal energy”, this does not increase the temperature of the atmosphere.”
To be clear, the ‘internal energy’ just mentioned is the kinetic + potential energy of excited rotational and vibrational states, and sometimes electronic states, and in extreme conditions, nuclear states.
This is distinct from the ‘internal energy’ that is (per unit material)equal to cv*T; this internal energy includes translational energy in addition to the others.
Rod B says
Ray (195), what you say here is correct. However the discussion wasn’t about my specific example per se, but more the process of skepticism (for lack of a better description). I was not looking for a scientific explanation for the specifics of my example; other than confine it to a specific area, there was no reason to explicitly define it.
My take would be
1, Denialist: “CO2 warming is not significant”
2, Alarmist: “Cite relative wikipage with an example (contains scintific sources).”
3, Denialist: “Uh, oh … blah blah”
Rod B says
Doug Bostrom (196) says
I think that is correct. I might prefer a term a bit stronger than “uncontroversial”, bit I’ll go with it for now.
Maybe the specifics of my example will help, though bear in mind, as per my last post to Ray, I’m not trying to actually scientifically resolve my concern here, just discussing the process of proof and skepticism. My skepticism: The current accepted estimate is that CO2 concentration going from 400 to 800 ppm will add 3.708 watts/m^2 forcing [5.35ln(800/400)]. I think the science supporting that projection from that level of concentration is sufficiently weak to warrant reasonable questioning.