RealClimate logo


Unforced variations: May 2020

Filed under: — group @ 1 May 2020

This month’s climate science open thread.

188 Responses to “Unforced variations: May 2020”

  1. 151
    Piotr says:

    Snape (149): “convection removes excess heat from the earth’s surface. Without it, it has been calculated that the average surface air temperature on earth would be somewhere around 125° F rather than the current liveable 59° F.”

    1. beware of sources using °F and feeling the need to explain to its reader that 125° F is not a “liveable” temperature. Really?

    2. if we ignore feedbacks (there is no indication that your source accounted for them) then the presence of thermals (24W/m2) cools Earth by under … 5C, a far cry from your warming by …37C (= 125-59 °F)

    3. IR emissions from Earth – 390W/m2, back radiation – 324W/m2, IR flux out out of atmosphere – 235 W/m2, albedo – 107W/m2, evapotranspiration 79W/m2, and you chose … 24W/m2 of thermals to talk about making the Earth liveable?

    4. Last but not least – in your original reason for bringing up thermals – larger extremes of temp. on Moon than Earth – you talk about thermals and … not about the heat capacity of the oceans? That’s like pontificating about the importance of a tree and missing the forest just behind it.

  2. 152
    Karsten V. Johansen says:

    In my view, there are very strong limitations in the (widespread) use of climate models to *accurately* predict future AGW (and it’s consequences), including our “carbon budget” etc.

    “Additionally, atmospheric CO2 concentration may also exert an impact on terrestrial and ocean biospheres and, hence, on surface albedo; as a result, climate change would be modified22,23,24,25. However, due to *the absence of a biogeochemical cycle in our modeling* (my markings KVJ), such modifications of atmospheric CO2concentration dynamics on climate change were absent. Thus, our study has not comprehensively considered all the impacts of atmospheric CO2 concentration dynamics on climate changes. Moreover, historical climate change was combined with the effects of external forcing and internal variability. In comparison to the real complex process of the earth climate system, we only focused on the radiation-related impacts of fossil fuel CO2 emissions, and the modeled climate is not comparable to observations.”

    https://www.nature.com/articles/s41598-019-53513-7

    The authors of this study nonetheless conclude that “we have overestimated” AGW (“by 10 pct.” sic! How can they even pretend that that number has any connection to reality?), and of course exactly that will be the typical media spin arising from this type of studies. Which is probably precisely what is intended by the flow of money to this type of “science”: to give an impression of “scientific basis” for continuing for the foreseable future the fossil business as extremely usual.

    The uncertainties in our knowlegde of both current ongoing and future AGW seems to me to very often be hugely underestimated, and moreover, all uncertainties are rather systematically seen as always playing out to let society even further relax it’s hitherto very limited – in fact completely absent – efforts to mitigate AGW. In fact, human use of fossil fuels shows no sign whatsoever of slowing down, on the contrary:

    https://i0.wp.com/runelikvern.online/wp-content/uploads/2018/06/fig-1-world-energy-consumption-1800-to-2017-vs-world-gdp-1980-to-2017-e1528939247704.png?ssl=1

    https://runelikvern.online/2018/06/14/the-powers-of-fossil-fuels-an-update-with-data-per-2017/

    So what we until now have seen regarding climate mitigation in reality, is only *symbolic politics*, ie. political media spin, almost only pure public relations. To put it bluntly: Media chatter from and among the chattering classes.

    Fiddling while Rome is burning.

  3. 153
    Snape says:

    @CCHolley

    “This NY Times article based on Hansen’s work shows how summers are getting hotter–gives the actual bell curve shifts over time”

    The article is behind a paywall, but I would definitely like to see the “actual” bell curve shifts. Hopefully an improvement over the ones I previously linked? And remember, I never claimed summers are not getting hotter – Tmins can increase and bring up the daily mean all by themselves. Dew points can rise and raise the heat index.

    My claims were specifically about how the trends for Tmaximums during summer are so much smaller than the others. Here again,

    CONUS, 1950 -2019
    June-August Tmax: +0.16F/decade
    Dec.- Feb. Tmin: +0.43F/decade
    Annual Tmean: +0.31F/decade

    https://www.ncdc.noaa.gov/cag/national/time-series/110/tmax/3/8/1950-2020?base_prd=true&begbaseyear=1901&endbaseyear=2000&trend=true&trend_base=10&begtrendyear=1950&endtrendyear=2020

    (I don’t have the global trends but I’m guessing they’re in the same ballpark.)

  4. 154
    Alastair B. McDonald says:

    Snape @149 quotes:
    “Besides creating the above-mentioned weather events, convection serves another purpose — it removes excess heat from the earth’s surface. Without it, it has been calculated that the average surface air temperature on earth would be somewhere around 125° F rather than the current liveable 59° F.”

    This is the answer to your original question which I think was: Why was there record temperature in the USA during the 1930s?

    Up until the 1930s, the plains were ploughed releasing the water in the soil. The dry ground was no longer cooled by evaporation. The plains are now irrigated with groundwater but when that runs out?

  5. 155
    CCHolley says:

    Thank you Kevin KcKinney @145 & MA Rodger @150

    So Snape assumes that since the overall average temperature of Canada isn’t increasing at a significantly higher rate than the rest of the global land mass then it would be a mistake to claim it is one of the fastest warming countries. I guess that’s a valid point; however, he does not back this claim up with the actual warming rates of other countries so it is only an assumption.

    Regardless, I believe the claim of Canada being one of the fastest warming countries mostly refers to its northern land mass and not necessarily the country as a whole.

    Note from CCCR 2019 in addition to the 1.7 C country wide average increase we also have:
    “Annual mean temperature over northern Canada increased by 2.3 C (likely range 1.7 C–3.0 C) from 1948 to 2016, or roughly three times the global mean warming rate.”

    Canada’s Changing Climate Report
    https://www.nrcan.gc.ca/sites/www.nrcan.gc.ca/files/energy/Climate-change/pdf/CCCR_FULLREPORT-EN-FINAL.pdf

  6. 156
    CCHolley says:

    RE. Snape @153

    The article is behind a paywall, but I would definitely like to see the “actual” bell curve shifts.

    I believe you get 20 on-line articles per month free from the New York Times, so you should be able to view it unless you’ve already viewed your allotment. If so, wait and try again, the article animates the shifts so it is well worth viewing.

    Harder to view and understand than the Times, but here are Hansen’s charts:

    http://www.columbia.edu/~mhs119/PerceptionsAndDice/

    My claims were specifically about how the trends for Tmaximums during summer are so much smaller than the others.

    As expected, winters are warming faster than summers for the reasons already explained.

  7. 157
    mike says:

    May 17 – 23, 2020 416.97 ppm
    May 17 – 23, 2019 414.72 ppm
    May 17 – 23, 2010 393.46 ppm

    some good news: https://www.maritime-executive.com/editorials/study-plankton-may-absorb-twice-as-much-co2-as-previously-believed

    but there is still a lot of extra CO2 ending up in the atmosphere and more CO2 equals more heat. I think it’s going to be a long hot summer.

    Warm regards

    Mike

  8. 158
    Snape says:

    @Alistair #154

    “Up until the 1930s, the plains were ploughed releasing the water in the soil. The dry ground was no longer cooled by evaporation. The plains are now irrigated with groundwater but when that runs out?”

    Right. This goes to my original “moon” argument, though. Water vapor is a major component of the GHE, and according to Gavin Schmidt, the atmospheric concentration increases about 7% with every 1 degree of warming:

    https://www.giss.nasa.gov/research/briefs/schmidt_05/

    Yet extreme heat events, like the dust bowl, were created by a LACK of water vapor. This is the sort of plot twist that for me makes climate science so interesting.

  9. 159
    Snape says:

    @Kevin McKinney #143

    “Also, on the ERL vs. surface question, it strikes me as a sterile distinction at best: surface conditions and TOA conditions can’t be delinked, even in simulations. So advocating that the greenhouse is “really” due to this or that aspect seems to me to be highly analogous to arguing which end of a pushrod is “really” doing the work.”

    This is my thinking as well, but a difficult position to prove.

  10. 160
    nigelj says:

    Snape has apparently created the ongoing impression he is a contrarian denialist by all this talk about summer extremes in America being generally less than in the 1930’s. However he said @110 “What interests me is the “why”. In this case, precipitation gives a clue:” Surely this is a fairly obvious clue hes not a denialist, and was talking about the counter balancing effect of increased precipitation? Come on people I’m a layperson, and I picked this up days ago!

  11. 161
    Snape says:

    @CCHolley #156

    Time for me to eat crow. In my struggle to understand the bell curves in the new link…..

    http://www.columbia.edu/~mhs119/PerceptionsAndDice/

    …… I realized I DID NOT understand the bell curves I originally criticized! Apologies to all.

  12. 162
    john r says:

    If someone could explain why the loss of summer arctic ice is significant I would appreciate it as surely:

    – in terms of absorbing sunlight the sun is still low on the horizon and therefore the bulk will be reflected rather than refracted.
    – the surface water is likely to be warmer than the surface ice and therefore will lose more heat to the atmosphere than the case where extensive ice coverage exists.
    – its a long way from anywhere significant (apologies to readers in Siberia and Alaska)

  13. 163
    MA Rodger says:

    The various comments up-thread regarding the moon’s temperature with/without atmosphere could do with some attention.
    I find the moon’s temperatures are not described at all well across the internet, probably because it isn’t a very complex or interesting climatological subject. Williams et al (2017) does provide a lot of data resulting from the Diviner Lunar Radiometer Experiment and some time back I scaled the data presented in Fig 9a to play with on a spreadsheet and which is where my lunar temperatures below originate.

    ☻ This lunar temperature issue kicked off up-thread with Snape @127 telling us “If you could introduce an Earth-like atmosphere to the moon, the mean temperature would increase but the maximums would fall like a rock.”
    Certainly the mean lunar temperature would increase from its present average of -73ºC, even if an introduced-lunar-atmosphere increased albedo significantly from the atmosphereless 0.12 of today. I’m not so sure with the “maximum”. If we take “maximum” to mean the equatorial noon-day temperature we can perhaps see what happens when the Earth’s atmosphere is removed. On Earth with an atmosphere, noon-day temperatures can reach something like +40ºC (eg the climatology here) yet with no atmosphere we have a model from contrarian Roy Spencer which shows a noon-day tropical maximum of 56ºF(= 13ºC).
    So an Earth with no atmopshere appears to have a lower “maximum” temperature. The moon with its 708-hour day has a noon-day equitorial temperature of 120ºC. Higher or lower with an atmosphere? Frankly I wouldn’t know what such a slow rotation would do to an earth-like atmosphere.

    ☻ Piotr @135 asserts that “it’s primarily the thermal inertia of the water in the oceans that makes Earth not having the temp. maxima like the Moon.” Of course water is a big complicating factor. Without long-lived GHGs in the atmosphere, water would end up relagated to part of the geology with the only melting under the noon-day tropical sun, that is if the water continued to be present in the tropics. And any daytime melting/evaporating with nighttime condensing/freezing would help spread the solar warming round the planet, reducing the diurnal range while also increasing the nighttime minimums. But would that make a difference in the drier parts of the planet? Possibly not.
    And surely the absence of water is not the ‘primary’ reason for the maximum daytime earthly temperatures being so low reltive to the lunar daytime maximums. The moon gets so hot “primarily” because it has a 708 hour daily cycle giving 359 hours of sunlight per day.

    ☻ The effect of wateriness on climate was converted into a discussion of the convection mechanism by Snape @149 with a citation of unknown reliability claiming the average Earth temperature would be boosted to 125°F (=52°C) in the absence of any convection. The atmospheric convection transports both sensible and insensible heat from the surface. Without such a flux, the surface IR would have to increase from ~400Wm^-2 to ~500WM^-2 to remain in equilibrium and thus (using S-B) an increase in average surface temperature from 17ºC to 33ºC, an increase of +16ºC. This is far smaller than the cited temperature of +37ºC.
    The prospect of adding climate feedbacks to boost the temperature increase suggested by Piotr @151 would not be appropriate as the primary feedback is contribution from water vapour. This short-lived GHG relies on the convection mechanism which we have switched off in this thought experiment. As a GHG water vapour contributes perhaps +24ºC to the present watery convecting climate. This perhaps suggests that the loss of convection, with the resulting loss of water vapour as a GHG, would actually cool the climate by a net -8ºC.

  14. 164
    Alastair B. McDonald says:

    Re 158 where Snape says: “Yet extreme heat events, like the dust bowl, were created by a LACK of water vapor. This is the sort of plot twist that for me makes climate science so interesting.”

    Snape, The dustbowl was caused by lack of water to provide evaporative cooling, not water vapour which is a function of specific humidity (SH). SH can be high even when relative humidity is less than 100%. Moreover, high air temperatures mean that SH can be greater without exceeding 100% relative humidity which also increases with temperature.

    The absolute humidity in the Sahara is 16 grams per cubic meter in August. See: https://www.worlddata.info/africa/western-sahara/climate.php

    Compare that with Greenland https://www.worlddata.info/america/greenland/climate.php

  15. 165
    zebra says:

    #162 john r

    Excellent question. But you have to understand that many of the comments/news articles you read on the subject are very poorly worded; it is often unclear what people mean by “summer” and/or “ice-free arctic”.

    What counts as “summer” to me is the period of most solar input, which goes from early May to early August.

    https://geography.name/insolation-over-the-globe/

    (See the fourth figure down.)

    It sounds like you are thinking of “summer” as the period of lowest ice extent, which goes from mid July to mid October. Go here:

    https://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/

    For the clearest picture, turn off the existing plots and click on the 4 decadal averages. (1991-2000, and so on)

    So, obviously, the high solar input during May, June and July is what is reducing the ice extent to the July to October lows. But you are then correct to point out that by September, when the ice is lowest, the solar input is greatly reduced.

    You are also correct that less ice means more energy loss to space, which is the mechanism by which the ice recovers.

    Sounds like you are someone who can figure it out from here. Some people tend to get overly excited about that very bottom minimum for September without thinking through the physics, which may be what you have seen in your reading.

    (And with respect to “why does it matter”… if we see the decadal drop start to accelerate, it will be an indication of more radical changes in global patterns.)

  16. 166
    CCHolley says:

    RE. john r @162 –The loss of summer arctic ice.

    – in terms of absorbing sunlight the sun is still low on the horizon and therefore the bulk will be reflected rather than refracted.

    This is simply not true. Neither the absorptivity nor the reflectivity of substances are dependent on incident angles. Although the intensity of the radiation is angle dependent and thus the amount of solar energy in the arctic is considerably less than that striking the equator, a much large percentage of that radiation is absorbed by the open water than by the ice. In fact, the loss of sea ice dramatically shifts the ocean surface from highly reflective to one that absorbs most of the sun’s energy. This ice loss will accelerate since the ice loss leads to warming of the ocean surface less ice will form and there will be even more ice loss.

    – the surface water is likely to be warmer than the surface ice and therefore will lose more heat to the atmosphere than the case where extensive ice coverage exists.

    And that is a big problem. The warmer open water warms the air and in turn raises regional land temperatures. Those higher air temperatures over land will eventually thaw permafrost thusly releasing vast stores of carbon—further amplifying climate change.

  17. 167
    Alastair B. McDonald says:

    Re #162
    Although the sun is low in the arctic during the summer, when the ice has melted the waves will still absorb the sunlight rather than reflect it.

    Moreover, although the angle of incidence is low the day length is up to 24 hours thus doubling the effective time compared with the tropics.

    The emission of black body radiation is a function of the temperature in Kelvin, not Celsius etc. Therefore, the relative temperature difference will not be very great, e.g. 1C to 10C = x10, 274K to 283K = x 1.03.

    The arctic ice provides about 5% of global albedo. Without that, global temperatures will rise by 20%, I.e. about 0.2×288 = 55 C.

  18. 168
    Snape says:

    @MA Rodger #163

    I’ve read through your comment several times now – really impressive. What is your background?

  19. 169
    Piotr says:

    john r (162)”surely in terms of absorbing sunlight the sun is still low on the horizon and therefore the bulk will be reflected rather than refracted.”

    “Surely”??? Let’s see:
    1. the Sun is not _that_ low – at the polar circle at noon in late June – 47deg. in late September – still 23 deg.

    2. Days are much longer – more time to absorb heat

    3. Although through part of the day , particularly around midnight, the sun is quite low – but even then you the reflection is not as high as you claim: even with Sun just above the horizon – still MORE light is refracted into the water than reflected: http://www.seafriends.org.nz/phgraph/phdwg33.gif
    5deg – 53% vs 47%, 10deg. – 73% vs 27%.

    4. Further – p.3 is for flat water – when you have waves, the side of the wave facing the low hanging sun is effective at much higher angle – the Sun may be 5deg above the horizon – but it may be be 30 deg or more above the sufrece of the wave

    5. Long angles are problem only for direct light – if you have overacast or fog – the effective angle of radiation is MUCH higher- i.e. where the reflection is negligible.

    Let’s go now to your 2nd argument:
    “– the surface water is likely to be warmer than the surface ice and therefore will lose more heat to the atmosphere than the case where extensive ice coverage exists.”
    Again – not really – summer air is almost always much warmer than the Arctic ocean so in summer the net movement of heat is still down, not up. Yes – ocean would give away more heat accumulated in summer when the ice would be reforming in the fall – but the net difference between these two is probably insignificant compared to the MAIN DIFFERENCE – the much larger absorption of solar radiation in summer due to albedo of seawater being of order of magnitude smaller than that of snow and ice.

    – “its a long way from anywhere significant (apologies to readers in Siberia and Alaska)”

    hmm, it _only_ triggered the change from having a couple km of ice over many mln of km2 of North America and Europe and …not having it: http://cdn.antarcticglaciers.org/wp-content/uploads/2012/07/Vostok_420ky_4curves_insolation_to_2004.jpg
    where “insolation 65N in June” is used as a stand-in for the Milankovitch cycles.

    “Surely its a long way from anywhere significant” ;-)

  20. 170
    Piotr says:

    MA Rodgers (163): “Piotr asserts”
    let’s not overuse big words – I merely pointed the absurdity of Snape’s argument – Snape tried to “prove” the supposedly important effect of Earth thermals on temp. extremes by comparing Earth with the …Moon. So I have merely pointed out that there are much bigger players causing the differences in extreme temps between Earth and the Moon.

    MA Rodgers: “surely the absence of water is not the ‘primary’ reason for the maximum daytime earthly temperatures being so low relative to the lunar daytime maximums. The moon gets so hot “primarily” because it has a 708 hour daily cycle giving 359 hours of sunlight per day”

    Piotr: Strong opinions (“surely”) require strong proofs. Yours is not:
    – with Moon’s very small thermal capacity – it does NOT MATTER how long is the day there: Moon is covered with highly insulating regolith – and as result its daytime temperature very closely follows the _instantaneous_ radiation flux from the Sun – that’s why in Fig.9 of https://www.sciencedirect.com/science/article/pii/S0019103516304869
    in all latitudes you see maximum right at the NOON. Which means that your daily maximum depends ONLY on what’s the incoming solar radiation at Noon.
    Ergo – it DOESN’T matter whether the daytime lasts 358 hrs or 3.58 hrs – the max temperature (i.e the temperature at noon) would be practically the same. On the other hand if you have an ocean, with its high heat capacity then the nights would not be as cold, and the days would not be as hot. That’s why Earths record temperatures are over land, not ever ocean.

    Surely you see now that daylength on the Moon does not really matter, right? ;-)

  21. 171
    Piotr says:

    MA Rodgers (163): “The prospect of adding climate feedbacks to boost the temperature increase suggested by Piotr @151 would not be appropriate as the primary feedback is contribution from water vapour.”

    Again: I didn’t “propose to add feedbacks to boost the temperature”, quite the opposite – I have carried the calculations for the most simplistic case – NO atmosphere hence no GHGs or albedo feedback. I.e. I did the same what you did later yourself, except that I have used Snape’s “convection of heat” in its narrow sense (thermals), while you have expanded it also on evaporative heat flux. As a result my increase in temp. was only +5C, yours was +16C (makes sense given that the evaporative heat transport being 3xlarger than by thermals). And we both noted that our results were _much_ lower than the +37C by Snape.

    And since neither my nor yours model included water vapour feedback – I am not sure how you can dismiss is my statements that if we included feedbacks – the temp. would have been higher.

    In other words – you CAN’T dismiss my statement that inclusion of feedbacks X,Y and Z may increase temperature in my model by saying that this statement “is not appropriate as … the primary feedback is X”.

  22. 172
    Piotr says:

    Snape: “Right. This goes to my original “moon” argument, though. Water vapor is a major component of the GHG, and according to Gavin Schmidt, the atmospheric concentration increases about 7% with every 1 degree of warming”

    But wasn’t your moon “argument” – an attempt to defend … your earlier “playing” a denier: “Playing contrarian……..23 states set their all-time high temperature in the 1930’s, compared to only 4 states where the record was set this century”

    When this was called out by several people who proved that you cherry-picked the local (Dust Bowl) data to suit your thesis – then not being able to prove them wrong – you went to … the Moon, as if Moon’s climate was a good analogy for the Earth’s.

    The problem is that in the process you … shot your _original_ claim in the foot – because if you admit that water vapour is a major, and increasing, GHG – then you help explaining why globally we have now MORE extreme heat records than in the past – NOT that we FEWER AS YOU CLAIMED ORIGINALLY, when you brought up the “US in 1930 ies” and used it “to start a conversation about the underwhelming trends in extreme heat”.

    To sum up – first you were proven wrong/dishonest about “underwhelming trends” and now you shoot yourself in the foot by providing mechanism to explain why there more heat records recently (warmer temp -> more vapour -> more heat extremes).

    Hey, maybe Nigel is right about you after all – maybe you are not a denier, but only pretend to be one to discredit them and their favourite claims? ;-)

  23. 173

    Questions from john r, @ #162:

    [Why is Arctic sea ice loss significant when]:

    – in terms of absorbing sunlight the sun is still low on the horizon and therefore the bulk will be reflected rather than refracted.

    Because:

    -“small” does not necessarily imply “insignificant”, much less “negligible”;
    -in any case, it’s almost certainly larger than you think. (I looked this up years ago, though I don’t presently have references handy. Reflection isn’t a linear function, the ocean rarely presents a planar surface, and a significant portion of ambient light is already diffused anyway, particularly in cloudy conditions–which, by the way, the Arctic is famously prone to.)

    And don’t you mean “absorbed” rather than “refracted?”

    – the surface water is likely to be warmer than the surface ice and therefore will lose more heat to the atmosphere than the case where extensive ice coverage exists.

    -Sure, and to some degree that will act as a negative feedback. But how much of that heat will make it to space, and how much will end up warming the atmosphere, and reradiating back to the ocean?

    -The temperature difference may not be very great in any case, as melt water is fresh, and therefore tends to create a somewhat persistent ‘lens’ of cold water at the surface.

    -If, in the contrary case, heat is mixed downward and warming at depth occurs, then you have long-term heating of the ocean. (Something, of course, being empirically observed everywhere.

    Relevant studies from a cursory search:

    https://journals.ametsoc.org/doi/full/10.1175/2010JPO4339.1
    https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009JC005849
    https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2010GL044136

    – its a long way from anywhere significant (apologies to readers in Siberia and Alaska)

    -Don’t forget readers in Nunavut, the Northwest Territories, the Yukon, northeastern Russia, and various parts of Scandinavia!

    -The value of the Arctic is not limited to humans; there is a whole unique ensemble of ecologies that have (many, including me, would assert) intrinsic worth.

    -Arctic conditions are believed, based on pretty strong evidence, to affect circulation on a hemispheric scale. “What happens in the Arctic does not stay in the Arctic.”

    Relevant study:

    https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-16-0257.1

  24. 174
    CCHolley says:

    RE. @166

    Neither the absorptivity nor the reflectivity of substances are dependent on incident angles.

    My mistake. This is mostly true up to a point.

    Reflectivity for water versus incidence angle: https://en.wikipedia.org/wiki/Reflectance#/media/File:Water_reflectivity.jpg

    For the summer solstice the incidence angle at the north pole is 23.5 degrees. For half of the day, half of the polar region has a solar incidence of greater than 23.5 degrees where reflectivity is still relatively low. For most of the summer, with open water far more of the solar radiation is absorbed than is reflected.

  25. 175
    Piotr says:

    – Kevin McKinney (#143) “Also, on the ERL vs. surface question, it strikes me as a sterile distinction at best: surface conditions and TOA conditions can’t be delinked, even in simulations.
    – to which Snape(159): “This is my thinking as well, but a difficult position to prove.”

    ??? Who cares about proving something that is “a sterile distinction”?

    And if you agree that “the ERL vs. surface question is a sterile distinction” why would you join this discussion to argue that … the surface is as importnat as ERL ???

    And do you often start discussion about things that you agree are … “sterile distinctions”? See your opening post in this thread:
    Snape (49)”believing that the increase in GHG’s nearer the surface also plays a critical role”.

    Thoughts?

  26. 176
    MA Rodger says:

    Piotr @170,

    Addressing your second point, you maintain the view that a lack of thermal inertia would give a moon spinning 100x faster than ‘actual’, a maximum noon-day temperature identical to the ‘actual’ temperature. Thus you consider the Earth spinning only 30x faster would also have such a max noon-day temp if it were a rocky planet like the moon.
    This contradicts my assertion @163. Note that @163 my use of the word “surely” is to indicate that I have no definitive answer but instead a strong answer, so a little more than “opinion.” And, yes, I presented no support directly for this assertion although the comment @163 does contain such.

    Your own argument relies on a visual inspection of Williams et al (2017) Fig 9a to assert that the maximum temperature at each latitude is seen at noon. But you will remember that I have scaled the data presented in this graph and while the timing of the maximum temperature is not apparent from such scaling, I could give you chapter-and-verse on the difference in temperature between sunlit am-warming and sunlit pm-cooling that is evidence of the thermal inertia measured on the actual 708hour spinning moon. The warmer nature of average sunlit pm temperatures can also be observed in Fig 10b when the difference is large enough to register (ie at higher latitudes).

    Now logic dictates that thermal inertia will become more significant as the spin is speeded up. Your assertion @170 is that this significance does not appear if the moon spins 100x faster. If you wish to model the impact of such an increased spin, I’d be happy to cast a jaundiced eye over it. You will note that I have already presented a modelled result @163, that provided by contrarian Roy Spencer (there is a link to the actual calcs), which suggests that a rocky Earth would not get anything like as hot as the moon does under the noon-day sun. If you find this model is flawed enough to overturn my assertion of a spinnier moon being cooler at noon and replace it with your own unchanged temperature on a spinnier moon, please do explain.

  27. 177
    Adam Lea says:

    162: “If someone could explain why the loss of summer arctic ice is significant I would appreciate it”

    It is significant to me living in the UK because I think the UK climate has changed, and Arctic amplification is the cause. The UK is known for its changeable climate, that changeability on the scale of hours to days in a zonal weather regime with low pressure systems coming through interspersed by ridges of high pressure. In the last decade or so, the weather seems to have lost a lot of its high frequency variability, and now seems to more frequently get locked in place, and we get months of wet followed by months of dry. We had five very dull and wet months during autumn-winter 2019/20, culminating in the wettest February on record, and since late March, hardly a drop of rain has fallen up to today (https://metofficenews.files.wordpress.com/2020/05/rainfall-stats-march-april-may-2020.png), and nothing significant forecast for the next week at least. It is causing me problems with gardening, my allotment was flooded in February, and is now like a dust bowl (thankfully clay soils hold water well), and despite having a cubic metre of stored rainwater at the beginning of spring, I am now almost empty. If these locked in weather patterns are a manifestation of a shift to a new climate, UK authorities need to seriously start looking at building resiliance in the infrastructure and agriculture to sustained periods of drought and flood, but I hear no-one talking about this. This concerns me.

  28. 178

    ABM 167: The arctic ice provides about 5% of global albedo. Without that, global temperatures will rise by 20%, I.e. about 0.2×288 = 55 C.

    BPL: A 5% change in global albedo would reduce it from 0.3 to 0.285. S is 1361.5 W/m^2, so F (absorbed climate flux density, 0.25 S [1 – A]) would change from 238.2625 to 243.368125, and Earth’s radiative equilibrium temperature would change from 254.60 to 255.95 K, a difference of 1.35 K, not 55 K.

  29. 179

    P 170: daylength on the Moon does not really matter

    BPL: It matters to the distribution of temperature. A fast-rotating planet radiates heat from 4 pi steradians, but a slow-rotating one only from 2 pi steradians, absent atmospheric and oceanic heat transfer. The day-night temperature contrast on the Moon would be much less if it rotated faster.

  30. 180
    Killian says:

    Scientists are learning just how fast the ice margin of Antarctica can retreat in a warming world.

    They’ve identified features on the seafloor that indicate the ice edge was reversing at rates of up to 50m a day at the end of the last ice age.

    That’s roughly 10 times faster than what’s observed by satellites today.

    https://www.yahoo.com/news/climate-change-stunning-seafloor-ridges-115944147.html

    But what the eff do I know…?

  31. 181
    nigelj says:

    The following article on new research looks very important “Antarctic Ocean Reveals New Signs of Rapid Melt of Ancient Ice, Clues About Future Sea Level Rise” It relates to the material in the very good article posted at 180 and goes into more detail on sea level rise:

    https://insideclimatenews.org/news/28052020/antarctic-ocean-ice-melt-climate-change

    According the the article it doesn’t change IPCC sea level projections this century but could have “substantial implications” beyond that. Read possible multi metre sea level rise per century.

  32. 182
    Piotr says:

    MA Rdoger (176): “you maintain the view that a lack of thermal inertia would give a moon spinning 100x faster than ‘actual’, a maximum noon-day temperature identical to the ‘actual’ temperature/”

    Yes because without ability to store heat (no thermal inertia), the temperature reflects the instantaneous radiation balance (heat from the Sun = Moon radiation out). Since the solar heat is max at noon – the max temp is also at noon, and the other temps are symmetrical around noon: e.g.: T(11am) =T(1pm).

    On Earth we have thermal inertia – which means that Earth accumulates heat a.m. (more heat in than out) and release it p.m., That’s in tropics the max. temp is NOT at noon, but. 3pm http://www.chanthaburi.buu.ac.th/~wirote/met/tropical/textbook_2nd_edition/media/graphics/daily_temp_lag.jpg

    MAR> This contradicts my assertion @163.
    That was the point (If I agreed with you @163. it, I would have not questioned it)

    >MAR Note that @163 my use of the word “surely” is to indicate that I have no definitive answer but instead a strong answer, so a little more than “opinion.”
    Def: “Surely – used to emphasize the speaker’s firm belief that what they are saying is true and often their surprise that there is any doubt of this.” So … what was your point here?

    > And, yes, I presented no support directly for this assertion although the comment @163 does contain such.
    Since I replied to your @163, I am lost – your @163 “presents no support” or “does contain such” ?

    MAR> Your own argument relies on a visual inspection of Williams et al (2017) Fig 9a to assert that the maximum temperature at each latitude is seen at noon.

    That and the fact that regolith is highly thermally insulating, thus limiting the ability of Moon to store heat, thus negating the importance of the length of the day (see later). Here is a quote from your source:
    “Large lateral temperature gradients are possible due to the highly insulating nature of the top few cm of the regolith with surfaces separated by distances a few mm able to remain thermally isolated in the lunar environment”

    > But you will remember that I have scaled the data presented in this graph and while the timing of the maximum temperature is not apparent from such scaling,I could give you chapter-and-verse on the difference in temperature between sunlit am-warming and sunlit pm-cooling that is evidence of the thermal inertia measured on the actual 708hour spinning moon

    You could but you didn’t, nor are doing it now – you don’t present your methodology nor the data, only your interpretation. Nor you explain what’s the reason/advantage/relevance for your “scaling”?

    But all these are details – more important that if Moon’s daylength were as important as you claim – shouldn’t the your PRIMARY reason have BIG impact? After all, we are talking about the reasons for over 100K difference (120C-13C)!
    And yet below you imply that such HUGE effects at the discussed location (equator) are … ” “too small to register”?
    By the size of their fruits you shall know their “surely primary” importance, eh? ;-)

    MAR> The warmer nature of average sunlit pm temperatures can also be observed in Fig 10b when the difference is large enough to register (ie at higher latitudes).

    I am not sure what the “warmer nature of average sunlit pm temperatures “ means and what exactly does it prove? And what does it tell you when your supposed “surely primary” factor is …. “too small to register” at the very latitudes where it matters? (we are talking about the reasons for the temperature _maxima_ – and those are at the equator, not “at higher latitudes”)

  33. 183
    Piotr says:

    Piotr – continued:
    MA Rodger (176): ” Now logic dictates that thermal inertia will become more significant as the spin is speeded up. Your assertion @170 is that this significance does not appear if the moon spins 100x faster. If you wish to model the impact of such an increased spin, I’d be happy to cast a jaundiced eye over it.”

    No point in doing so, since with so low heat inertia – it does not matter how quickly Moon spin – if you can’t store heat during morning then your max temp. is always at noon, whether the noon comes every 24 (Earth) hours, or every 708 hrs.
    max temp. there is at noon.

    And for the record – I don’t agree with the dictates of your logic even for oncet that do have large thermal inertia – here the impact of spin rate is only in the middle
    i) LOW when the spin is very fast – there is not enough time to absorb enough heat to make a difference
    ii) LOW AGAIN at the other end of the scale – _very slow spin –> inertia’s impact is saturated (the IR emission are proportional to the 4th power of T, so if during the long day you have stored enough heat to increase your temp – you are losing it at a much higher rate). Which means that the further extension of the day-length doesn’t change much.
    iii) so the day-length may be important only in thermally inert systems at INTERMEDIATE rotation speed (a sweet spot of having enough time to accumulate enough heat and not long enough to saturate this effect )

    But for our discussion – the Moon with its v. low thermal inertia – its spin rate DOESN”T matter for the max temp. one way or another.

    MAR> You will note that I have already presented a modelled result @163, that provided by contrarian Roy Spencer (there is a link to the actual calcs), which suggests that a rocky Earth would not get anything like as hot as the moon does under the noon-day sun

    Yes, I noted that you … provided a link to some non-peer-review model, by a climate change denier, published on his own website, quoted a number nobody questioned, and then failed to explain how this tautology is supposed to prove _your_ claim. Not a terribly high standard of proof, if you ask me.

    MAR > If you find this model is flawed enough to overturn my assertion of a spinnier moon being cooler at noon and replace it with your own unchanged temperature on a spinnier moon, please do explain.

    My problem is not with the denier’s model you call upon – but with your inability to show how his findings are supposed to prove your claims.
    Particularly that you already had in your hand a much better test – the peer-review paper and not from a hypothetical very simplified Earth but actual Moon – and you failed to show there a _massive_ asymmetry in the p.m. temperatures – something that would be required to prove your self-confident claim:

    “surely the absence of water is not the ‘primary’ reason for the maximum daytime earthly temperatures being so low reltive to the lunar daytime maximums. The moon gets so hot “primarily” because it has a 708 hour daily cycle giving 359 hours of sunlight per day.”

  34. 184
    Piotr says:

    Killian (180): “They’ve identified features on the seafloor that indicate the ice edge was reversing at rates of up to 50m a day at the end of the last ice age. That’s roughly 10 times faster than what’s observed by satellites today.”

    Piotr: yes – although this is a bit of apples and oranges -youu take short term rates probably from the peak of summer and … extrapolate onto the rest of the year? A more fair comparison would have been to find analogous bottom structures formed today and compare their spacing with the old ones.

    K. “But what the eff do I know…?”

    Nah, don’t beat yourself up, Killian – your point that the future climate change may be much worse then we think (if the ice was once retreating _that_ fast, then we haven’t seen anything yet) is well taken! Good catch!

    Piotr

  35. 185
    MA Rodger says:

    Piotr @182 & @183,
    You seem to be of the view that a solid rocky object has no (or ‘no significant’) thermal inertia. I don’t know why you would hold such a view.
    I will constrain my reply to the points of your deconstruction that will hopefully advance matters for you.

    You say the moon is “without ability to store heat (no thermal inertia).” Consider this.
    The night-time moon has no incident sunlight yet, unlike your effectively-zero-inertia rock, it has a surface temperature of between -157°C and -178°C averaged on its equator. Where does the energy come from to maintain such a temperature, well above absolute zero? (I wouldn’t give any heed to there beeing a hot lunar core, cool by Earthly standards, buried within the moon that is 1,400km deep, very deep by Earthly standards.)

    You assume that my “chapter-&-verse” on the difference between morning & afternoon is not worthy of consideration/investigation and thus to be ignored, even thought I evidently think otherwise or I would not have mentioned it. “For the record,” the asymmetry of lunar equitorial am/pm temperature present in Williams et al (2017) Fig9a suggests the maximum temperature on the lunar equator arrives six hour after the sun has passed its zenith. (So, as a proportion of the daylength, that is routhly a fifteenth the time-lag seen on Earth.)

  36. 186
    Killian says:

    Re new Antarctic melt rates:

    “Let us take a step back and admit that no model would have predicted what we are seeing today,” he said. “So we have to be humble about this and recognize that there are still a lot of elements we do not know in terms of how fast an ice sheet can fall apart.”

    And perhaps start admitting that others, not constrained by scientific reticence and willing to consider non-climate science error bars and concepts were able to see this much sooner, and far more accurately.

    While the new findings shouldn’t affect current projections that sea levels will rise between 1 and 4 feet this century, beyond that they could have substantial implications, Rignot said.

    That’s one hell of an assumption and implied caveat. “Well, we’ve been too conservative by an order of magnitude, but probably we’re not now… at least, not for the next 80 years or so.

    Anyone else got a cold, not fuzzy feeling about that assumption?

    “The most important message to take home is that the current projections are too conservative. We know it,” he said. “The real drama in all of this is that the faster rates of retreat may turn out to be the most probable in some places, and as of now we do not know where and when.”

    Most probable? They’re all probable… because they already happened in far more stable conditions. They’re freaking certain. Yes, the only question is when.

    Perhaps *now* some of you are willing to start listening to the urgency of shifting to a risk-based discussion of climate and uncomfortably short time line probabilities?

  37. 187
    Piotr says:

    MA Rodger (185) “You seem to be of the view that a solid rocky object has no (or ‘no significant’) thermal inertia.”

    Piotr: No, that’s not my view – I didn’t generalize to “a solid rocky object” , but stuck to the topic of this discussion: the Moon, and used Moon data to support it.

    MA Rodger: “I don’t know why you would hold such a view”.

    Piotr: I thought I have explained it several times already, in posts you read and commented.
    1.In posts (170, 182) – I explained the REASON for the low thermal inertia, using the very same paper … you brought in to support your claims ( Williams et al (2017).) Piotr: (170, 182):
    “regolith is highly thermally insulating, thus limiting the ability of Moon to store heat. Here is a quote from your source: “Large lateral temperature gradients are possible due to the highly insulating nature of the top few cm of the regolith with surfaces separated by distances a few mm able to remain thermally isolated in the lunar environment”

    2. Then I used, again, your own source to PROVE my claim: by their fruits you shall know them: if the length of day were important then the max temperatures would be skewed toward p.m., like on Earth. But they are not: see my posts (135, 170, 182, 183), e.g.:
    “without ability to store heat (no thermal inertia), the temperature reflects the instantaneous radiation balance (heat from the Sun = Moon radiation out). Since the solar heat is max at noon – the max temp is also at noon, and the other temps are symmetrical around noon: e.g.: T(11am) =T(1pm).” “that’s why in Fig.9b of Williams et al (2017) in all latitudes you see maximum right at the NOON. [as opposed to the asymmetrical temps on Earth where] in tropics the max. temp is NOT at noon, but. 3pm http://www.chanthaburi.buu.ac.th/~wirote/met/tropical/textbook_2nd_edition/media/graphics/daily_temp_lag.jpg
    And after reading all these – you still “ don’t know why [I] would hold such a view.” ?

    MARodgers: “Consider this.The night-time moon has no incident sunlight yet, unlike your effectively-zero-inertia rock, it has a surface temperature of between -157°C and -178°C averaged on its equator. Where does the energy come from to maintain such a temperature, well above absolute zero?”

    Piotr: From the fact that the same layer of regolith would have different thermal inertia in different temp. The definition of thermal inertia: “ the degree of slowness with which the temperature of a body approaches that of its surroundings.”
    Given that the Moon’s surface at equator has temp. a NIGHT temp . ~100K, and at Noon ~4000K, it means that the radiative heat loss at noon – is 256x LARGER. That’s why the temp. dramatically drops after the noon, and that why it flattens out after the sunset.
    In other words – the local minima temp. on Moon would be somewhat higher if the Moon rotated with Earth’s speed, but the absolute minimum would not – since these are at the poles and you don’t get much solar rad. there even at the noon.
    But that’s beyond the point – we discuss here the temp MAXIMA e.g. “noon-day tropical maximum” [MA Rodger;163]”. And for temp. maxima – it DOESN’T MATTER how long is the day – with the heat loss rate 250 times higher than at night – whatever little heat has been stored there – it is quickly being lost. Hence “low inertia”. As I said in (182):
    “without ability to store heat (no thermal inertia), the temperature reflects the instantaneous radiation balance (heat from the Sun = Moon radiation out). Since the solar heat is max at noon – the max temp is also at noon, and the other temps are symmetrical around noon: e.g.: T(11am) =T(1pm).” “that’s why in Fig.9 of Williams et al (2017) in all latitudes you see maximum right at the NOON [as opposed to the asymmetrical temps on Earth where] in tropics the max. temp is NOT at noon, but at 3pm http://www.chanthaburi.buu.ac.th/~wirote/met/tropical/textbook_2nd_edition/media/graphics/daily_temp_lag.jpg

    To sum up – almost^* all of the above arguments were in the posts you commented, so if you are still perplexed “why [I] would hold such views”, I am not sure what more I could possibly say.
    Piotr

    ===
    ^* the only new part of the current post is the explanation of the slower radiative heat losses at lower T, which I didn’t think I needed to explain to somebody who is on the initial basis with Stefan and Bolzmann (“and thus (using S-B) an increase in average surface temperature”) ;-)

  38. 188
    MA Rodger says:

    Piotr @187,
    I’ve said my piece. I would suggest you re-read what is said @185 but I know it can be so very difficult struggling through a couple of hundred words which set out what you clearly don’t want to hear.