Thin tropical clouds cool the climate

From STOCKHOLM UNIVERSITY:

On this picture, thin mid-level clouds are observed in the foreground with deep convective clouds in the background. CREDIT Photograph: Radovan Krejci, co-author of the study

On this picture, thin mid-level clouds are observed in the foreground with deep convective clouds in the background.
CREDIT Photograph: Radovan Krejci, co-author of the study

Thin clouds at about 5 km altitude are more ubiquitous in the tropics than previously thought and they have a substantial cooling effect on climate. This is shown in a recent study by researchers from Stockholm University and the University of Miami published in Nature Communications. The cooling effect of mid-level clouds is currently missing in global climate models.

“Using the satellite observations and high-resolution numerical modelling, we find that thin mid-level clouds are frequently formed in the tropics in the vicinity of deep convective clouds and that their cooling effect could be as large as the warming induced by high cirrus clouds”, says lead author of the study Quentin Bourgeois, postdoctoral associate at the Department of Meteorology (MISU) and the Bolin Centre for Climate Research, Stockholm University.

Clouds play a pivotal role in determining the Earth’s climate and radiation budget, yet we still have a lot to learn about them. In particular, little is known about mid-level clouds, i.e. clouds located at approximately 5 km altitude, as these clouds are challenging to study.

“To bridge our gaps in knowledge about thin mid-level clouds we used space-borne lidar instruments that provide detailed information on the vertical distribution of clouds”, says Quentin Bourgeois.

The scientists anticipate that their study will trigger further interest in thin mid-level clouds, which have been neglected for too long. In particular, the mechanism of their formation is not well understood yet. The authors also hope that the climate research community will factor in clouds in climate models more often in the future so that projections of climate change will become more accurate.

Clouds effects on global climate

Clouds cover about 70% of the Earth’s surface at any time. Different types of clouds affect the Earth’s climate differently: low liquid clouds, such as the cotton-like cumulus, cool the Earth while high altitude ice clouds, such as the wispy cirrus, warm the climate. Overall, clouds cool the climate by about 20 W m-2. In contrast, the Earth receives on average about 340 W m-2 energy from the sun every day and our current emissions of anthropogenic greenhouse gases warm the climate by about 3 W m-2.

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82 thoughts on “Thin tropical clouds cool the climate

      • Wow, I have not seen that video before. Very powerful message not only about the wonderful process of science discovery and collaboration, but equally at how stubborn mainstream science can be at quashing new ideas they don’t like. I particularly liked the bit showing the arrogant “cloud expert” attacking him both during and after his presentation and declaring “everything is known about cloud condensation aerosols and perhaps he should read his book on the subject.”

    • Most people are careful not to look at the sun. AGW scientists take great care not to look closely at the clouds!

      • Excellent ! That about sums it up.
        As I said in my article on tropical feedbacks over at C.E.

        AR5 WG1
        7.4.4.2
        Satellite remote sensing suggests that aerosol-related invigoration of deep convective clouds may generate more extensive anvils that radiate at cooler temperatures, are optically thinner, and generate a positive contribution to ERFaci (Koren et al., 2010b). The global influence on ERFaci is
        unclear.
        WG1 are arguing from a position of self-declared ignorance on this critical aspect of how the climate system reacts to changes in radiative forcing. It is unclear how they can declare confidence levels of 95%, based on such an admittedly poor level of understanding of the key physical processes.

        https://judithcurry.com/2015/02/06/on-determination-of-tropical-feedbacks/

    • Evidently, nobody at Stockholm University reads WUWT.
      I don’t know how many times I have written here that more clouds (for periods of climate validity (like 30 years) block and refract / reflect solar energy from reaching the deep oceans where it is stored as heat and other products, to show up nobody knows when sometime(s) in the future.
      Well everything that is gonna show up, will do so in the future.
      Less solar energy reaching the condensed state surface interface with the gaseous state, means less surface heating. We live on the surface, and that’s where we hang our kitchen door thermometers.
      Hey Stockholm U, I think your should give due credit to WUWT for announcing this discovery first.
      G

    • “””””….. Thin clouds at about 5 km altitude are more ubiquitous in the tropics than previously thought …..”””””
      Well at least by us; and what do we know about it ?
      And of course if we never thought about it, we are quite sure nobody else did either.
      g

  1. I have argued for years that the Svensmark effect would me most pronounced in areas where there is abundant moisture but limited condensation nuclei present. Any chance mid-level clouds in the tropics would be an area with detectable relationships to GCR changes?

    • “I have argued for years that the Svensmark effect would me most pronounced in areas where there is abundant moisture but limited condensation nuclei present. Any chance mid-level clouds in the tropics would be an area with detectable relationships to GCR changes?”
      I looked there and found no effect.

    • Tex
      You pose the question as an altitude issue, but it can be constrained better. Ask if GCR has a obvious effect on regions with two factors: a high absolute humidity with a low concentration of CCN and the right altitude.
      That combination appears in the tropics generally and in any summer region where rainfall is normal, i.e. no for Cape Town but yes for coastal British Columbia.
      As to the scale of the GCR effect, CERN already reported it was greater than expected.

      • And climate phenomena are NOT just last night’s weather you need 30 years to detect a climate change.
        I don’t think Mosh has been measuring solar radiation globally underneath the clouds, for 30 years.
        G

      • British Columbia having “normal” rainfall. Really? On the Prairies we used to joke they had webbed feet there

      • For Kendall:
        The coast of BC is quite wet and cloudy in winter, with periods of cold and sunny, but quite dry and sunny in summer. Winter is cool so rate of evaporation low.
        And an example of variation: in SW BC this summer, early August had more rain than usual, whereas late August is drier so far (late August weather is typically mixed, not bad but take an umbrella to the PNE)

  2. And there have been multiple postings on how badly if at all Global Circulation Models account for clouds, period. But we must trust the GCMs anyway. Just ask the IPCC. 🙂

    • It is! It’s just the sun, the clouds, the ice, the deep ocean, the UHI effect, the deep ocean and a few other details we need to figure out yet. But yeah, it’s settled!

      • Not to mention how long the collective critter corpses remain outgassing in the Sun, before George Monbiot et cie, devour them and provide a sort of time- delay effect on any CO2 release, a time delay effect of the same sort as CO2atm provides for heat transfer to space. This and other atmospheric/climate effects may be random, or orchestrated in some way by an unseen hand(s.)
        Inquiring minds want to know… could it all be God’s will, or just somebody else’s fault?

      • (I’m in the God’s will camp, myself ; )
        ~ Dost thou know the balancings of the clouds, the wondrous works of him which is perfect in knowledge? ~
        (Job 37:16)

    • “I know everyone hates to hear this again, but I thought the science was settled.”
      Repeat after me.
      These are the settled areas
      1. C02 is a GHG
      2. Our FF use is increasing C02
      3. Increasing C02 will warm the planet
      4. How much warming…. between 1.5 and 4.5C per doubling
      What is unsettled?
      5. Is it closer to 1.5C or 4.5C?
      6. How much damage will that cause
      7. What can we do?
      in other words “The” science is an ambiguous. term.
      stop being ambiguous.
      [Note: you forgot number 8 – The surface temperature record has uncertainty that may be greater than the climate signal sought There’s ambiguous for you. – Anthony]

      • “4. How much warming…. between 1.5 and 4.5C per doubling”
        Two points:
        1.5 to 4.5C per doubling is a fairly wide range for something “settled”
        and
        Isn’t it “may be” between 1.5 and 4.5C per doubling, not the “settled” Bill Clinton “IS”?

      • Increasing C02 will tend to warm the planet, all else being equal one aspect of which this article is all about, and any damage caused by warming due to fossil fuel use is far outweighed by the benefits which are obvious and everywhere.

      • 6. How much benefit will this bring? You’re barking up the wrong tree, moshe. Barking louder won’t bring you satisfaction.
        ===============

      • “Jamie
        August 17, 2016 at 2:16 pm
        Anthony…what do you believe the error in the surface temperature is?”
        Oh about that is accurate within .2 C.
        And can you precisely define what surface temperature is?

      • Steven – There’s another very big item that is unsettled – how will water respond to warming that is deemed to be caused by increasing CO2? Will water vapour amplify the GHE of CO2, as predicted by “the models”, or will it make more clouds, increase albedo and offset the GHE of CO2, as my gut feeling suggests is not unlikely. This article throws a little light on that question, and it does point out how poorly understood clouds really are..
        There are a few other unsettled things that impinge on how climate will change in the future: what will the following climate inputs do: TSI? sunspots? earth’s magnetic field? ocean circulation regimes? Volcanoes, too. No doubt there’s more but I’m tired tonight.
        My gut feelings, as I put it, are heavily influenced by my education in geology, and a career spent looking mostly at Precambrian rocks. These help you look at the tiny slice of earth history that has been documented by instruments in a proper perspective. The earth has gone round the sun approximately 4,500,000,000 times, and there has been life on it for about 90 percent of that. Before the atmosphere had any oxygen in it (about half of the earth’s history to date), its CO2 content was somewhere in the region of 200,000 ppm and the seas did not boil (and we are supposed to panic about the possibility of 500 ppm?). I could go on about really obvious things that never seem to concern alarmists, like – of course it’s warmer now than in “pre-industrial” times because we have gone from a stadial to an interstadial.
        In fact, for all the money that’s been thrown at Climate Science, the “unsettled” items seem to this observer to very much outweigh the “settled” ones.
        Steven, you are obviously very well educated, intelligent and hard working. If I can offer one drawback to those virtues, it’s that you are so immersed in climate data; perhaps your view of the forest is obscured by all those trees,

      • Gee, after AR4 you would have been saying “between 2.0 and 4.5C per doubling”. 2 to 4.5 wasn’t “settled.” Jury is out on whether 1.5 to 4.5 remains settled. How long do you think it will be before the temperature record forces IPCC to drop the 4.5 to something lower? The 4.5 already looks ludicrous when you at what the rate needs to increase to, to get to 4.5 with 16 years already in the record books.

      • How “settled” is really the lower bound of 1.5C per doubling? Isn’t that currently more like a committee decision than established science?

      • We’ve seen a Large number of research papers which say in the range of 1.5C, mosh. Do you disagree with them and why?

      • ClimateOtter says:”We’ve seen a Large number of research papers which say in the range of 1.5C, mosh. Do you disagree with them and why?”
        The problem is that 1.5C just isn’t very scary, and is most likely beneficial. 4.5C, though, now that’s a good scary number worthy of drastic leftist political action. Not only that, but there is plenty of research indicating that CO2 has an ECS of less than 1.5C, and possibly less than 1.0C.
        Why is this Mosh guy listed in the “lukewarmers” catagory? He’s clearly an alarmist in lukewarmers’ clothing.

      • Hey Mosh, we aren’t the one going on and on about how the science is settled. That would be your camp.
        PS: I love the bias in point 6, you are assuming that any warming must cause damage.
        Nice, ignorant but still nice.

      • PS: Most of the recent science puts the climate sensitivity of CO2 to below 1C, perhaps as low as 0.3C.

      • Jamie: Until recently, temperatures were only recorded to the nearest 1C. So to claim any accuracy greater than 1C is, to be kind, absurd.
        That 1C is only possible if the surroundings are perfectly maintained. We already know that this was not done. This is a major increase in the uncertainty.
        Finally, only about 1 or 2 percent of the earth’s surface came even close to be adequately monitored. Anyone who thinks that they can say anything meaningful about the earth’s temperature with that kind of monitoring is blowing smoke.
        My personal position is that the error bars for the era prior to satellite monitoring was at best +/- 5C, more likely closer to 10C.

      • Smart Rock: Beyond water vapor’s ability to form clouds, evaporation also moves a huge amount of heat from the water surface to high into the atmosphere where that heat can escape to space much more easily.
        Increased evaporation by itself, even without considering clouds, is a huge negative feedback.

  3. “The scientists anticipate that their study will trigger further interest in thin mid-level clouds, which have been neglected for too long.”
    But surely the various GCM have taken a complete distribution of clouds into account, including mid-level clouds.

  4. I recently watched thunderheads building one afternoon into anvil tops. I’ve heard those anvil tops are around 50,000 ft. Beats me. Far above those, were thin amorphous structures, of the type seen in Winter. As the Sun dipped to the Horizon, the various colors from that thin layer were of the sort that artists have so far failed to capture, as if they were from a muted prism. I think that layer must have had a substantial quantity of ice crystals, on a very hot day.
    disclaimer: those mentioned cloud formations have official names beyond my country boy descriptions and the mention of “ice crystals” is guesswork.

    • pimf: Thunderheads didn’t build an afternoon, they developed into anvil tops… in case any grammar teachers are around.

      • Not much of a jet over much of the tropics, with the exception of transient subtropical jets in the winter hemisphere.

    • Alan, no matter how hot is was at the surface, it was extremely cold at 50,000 feet.
      The average lapse rate of the atmosphere is given as about 4 degrees per 1000′, and to get air to rise unstably (like for a thunderstorm to form), it needs to be higher than the dry adiabatic rate of about 5.4 degrees per 1000′.
      It may be that there are layers that had inversions and it was more like -60 degrees than -100 or -125, but it was very very cold up there.
      Ice crystals?
      Um, yup!

    • Well the Atmospheric Temperature up there can be below -60 deg. C (reported on an airliner at 34,000 ft).
      So you are quite safe in guessworking “ice crystals”.
      Ice crystals are more chic than crystal balls.
      G

  5. Infrared light being scattered back into the sky at 5 km (about 18,000 feet) fails to penetrate nearly half the atmosphere, where half the CO2 is. These clouds greatly mitigate (by about 50%) the IR absorbtion of the atmosphere attributable to CO2, directly reducing the mis-named atmospheric “greenhouse effect”.

    • Low cloud provides for an IR spectrum which is almost a perfect blackbody. The CO2 spectrum is covered of course but so is every other spectral frequency.
      Now, how often are low clouds present. Up to 50% of the time.

      • Mosh
        “co2 is dominate because it strictly regulates the height of the ERL.”
        Water is dominant. It is also not well distributed and moves in three forms. It completely messes up the concept of an ERL at a particular altitude. CO2 cannot be dominant, full stop because it cannot accumulate and there just isn’t enough of it. It only has a thin maximum influence. What it does ‘strictly’ is make a contribution to warming that is swamped by water vapour and clouds.
        The difference between a conceptual physical model and a real atmosphere is evidenced by the difference between the predictability of CO2 and the unpredictable behaviour water.
        I agree that in a dry atmosphere CO2 would set the ERL. But there is no RL, the ERL is a mathematical construct.

      • The ERL is a pseudoscientific construct, equivalent to “The average person has one boob one ball,
        and 2 1/2 kids
        In actuality, about 40 watts is radiated from earth’s surface and escapes directly to space.
        An additional 150 watts or so is radiated from clouds directly to space.
        With most of the energy reaching the ground being radiated directly back to space from the surface or cloud tops

      • In response to MRW. ERL is short for “effective radiation level” See figure 4 in Held and Soden’s paper here.
        http://www.mathaware.org/mam/09/essays/Radiative_balance.pdf
        We’re arguing that the construct is physically unrealistic, since the effective radiation level is actually the average of radiation directly from the surface, from clouds, from water vapor, and factoring out any increased in the latent heat of convection and evaporation. The ACTUAL radiation level , an imaginary abstraction, would increase nowhere near as mucht as the fearmongers hypothesize.

  6. Interesting study.
    Low clouds cool the earth………..and high clouds warm the earth.
    http://earthobservatory.nasa.gov/Features/Clouds/
    By how much?
    Increasing water vapor has decreased the lifting condensation level……..more low clouds and earlier in the day, a negative feedback.
    Still much to learn about the effect of clouds on temperature. Clouds may be the biggest wildcard with models.

    • … along with evaporation, condensation, precipitation, that means they don’t just have a wild card they have a whole suit of wild cards. The afore mentioned factors make a royal flush of wildcards.
      Trump that!

  7. “…the Earth receives on average about 340 W m-2 energy from the sun every day and our current emissions of anthropogenic greenhouse gases warm the climate by about 3 W m-2.”
    Is that last figure correct? I just read somewhere else that it’s more like 0.8 W m-2.

      • Richard Petschauer

        The 3 Wm-2 is from CO2 doubling that will take over 100 years.

        What is the probability of (1) that CO2 doubling of actually happening?
        What is the probability of (2) that potential doubling of CO2 of actually increasing temperature by 0.5 degree or less?
        What is the probability of (3) that potential doubling of CO2 of actually increasing temperatrue by 1.5 degree or less?
        What is the probability of (4) that potential doubling of CO2 of actually increasing temperatrue by 2.5 degree or less?
        What is the probability of (5) that potential doubling of CO2 of actually increasing temperatrue by 3.5 degree or less?
        Finally, IF the temperature does increase, what the actual “harm” of it increasing by less than 2.5 degrees by 2100?
        Finally, IF the temperature does increase, what the actual “harm” of it increasing by less than 3.5 degrees by 2100?
        Finally, IF the temperature does increase, what the actual “harm” of it increasing by less than 4.5 degrees by 2100?
        Now, if the

      • RACook
        Thanks for asking a question I can answer with 95% confidence:
        What is the probability of (1) CO2 doubling actually happening?
        Zero chance.
        At the current extraction rates, and the rate of increase in that rate, and the availability of the resources, plus a 100% assumed increase in the total estimated availability, and the time it takes to extract those resources, and the sinking of early emissions into the oceans and biome, the following happens:
        Peak uranium 2035
        Peak energy 2050
        Peak coal 2070
        Peak CO2 530 ppm
        The only way out of this inevitable decline in available energy is the development of nuclear powered sources that do not rely on uranium. Once the energy supply problem is solved many, many things will change. Energy is wealth.

  8. Can I get an “I told you so!” for Willis who has pushed hard on the emergent phenomena button for several years?

  9. Global Averages are largely a waste of time. Look at the raw data in each area of the planet. It will tell you a lot more about, both, the weather and the climate. Ie. Poles, land – desert and forest, ocean, tropical, and mid latitudes. All can average 17C but max/ mins differ greatly. Even a stopped watch is right twice a day. More research into SH polar vortex and ozone profile with altitude is needed. The current chemistry theory does not match observations, thanks to nullschoolearth even I can see that.

  10. Of course, the cooling effect isn’t enough to offset the Catastrophic Man Made Global Waming, is it?
    We’re still doomed, I hope.

  11. We are so accustomed to clouds that we forget about why they are there.
    The most logical reason for their existence is to take part in a thermostatic feedback process to modulate surface temperatures.
    Why else would they exist? What other functions do they have in the grand plan of Nature?
    Geoff.

    • Possibly to redistribute a bit of fresh water that most life on land requires? But I agree. They most probably modulate surface temperatures. I’ve never seen a system yet that survived more than an instant with only positive feedback.

  12. Thin clouds at about 5 km altitude
    =============
    Co-incidentally the center of mass of the atmosphere is also 5km. And when multiplied by the lapse rate of 6.5C/km you receive a surface warming of 32.5C, which co-incidentally matches the so called greenhouse effect.

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