Reduced Cloud Cover, Not CO2, behind Warming
In 2021 we reported on a pair of studies (here and here) that analysed satellite-measured data and found that clouds were not shielding the Earth’s surface from incoming solar radiation as much as they used to, causing an increase in heat absorption at the surface which accounts for much of the warming experienced in the past few years without reference to ‘greenhouse gases’
Speaking of which, an especially surprising feature of those studies was that while extra solar energy was accumulating at the surface, the total amount of longwave radiation at the top of the atmosphere was going up.
Why is that surprising? Because the crux of climate orthodoxy is that more CO2 (plus other ‘GHGS’) in the atmosphere is trapping more of that radiation and letting less of it escape back into space, thus heating the planet.
And now one of the teams is back with a new paper with updated data that shows… more of the same. Over the past 20 years the net inflow of energy into the Earth’s atmosphere has doubled, mostly because more is being absorbed at the Earth’s surface.
But at the same time more is being expelled by the atmosphere, opposite to what would be expected from increased ‘greenhouse gas’ levels. Yep, climate is complicated.
Let’s start by looking back at the second of the studies we mentioned in 2021, by Dubal and Vahrenholt. They presented a remarkable graph of cloudiness and outgoing longwave radiation (meaning thermal, and known as OLR) from 1980 to 2020:
Around 2000 there was a dramatic, mysterious drop in average cloud cover, which the authors attribute to oceanic changes in the Pacific region and which the standard climate models cannot begin to account for.
Since on the whole clouds reflect heat, with less cloud cover the Earth warms up. Meanwhile if CO2 is the “The Thermostat that Controls Earth’s Temperature” as NASA’s Goddard Institute for Space Studies infamously claimed in October 2010, trapping OLR instead of letting it escape, then as carbon dioxide increases in the air the OLR should be dropping.
In fact it has to be. But instead OLR jumped just as cloud cover plummeted, and has continued increasing ever since.
That chart of course only goes up to 2018. But in the new Loeb et al. paper the post-2000 data are shown as follows, with the red line in the top panel showing Absorbed Solar Radiation and the blue line OLR.
The green line in the bottom panel is the net effect of the two in combination, graphed along with gray bars showing the “Multivariate ENSO Index” (a measure of the intensity of an El Niño Southern Oscillation event) to demonstrate that they do not correlate with it:
The top panel shows Absorbed Solar Radiation or ASR, the amount of heat the planet is gaining overall, going up steadily for 25 years, which the authors attribute not only to reduced cover of certain kinds of clouds but also lower reflectiveness of other cloud types, and here again the authors tie it to oceanic changes in the Pacific region.
And the blue line in that panel might seem to show OLR decreasing, except that it’s counterintuitively measured as if you were upside down at the top of the atmosphere, indicating how much is being trapped so the line going down means more heat escaping to space.
What does this mean? We’re not the sort of simpletons who declare ‘the science is settled’, or think one study ends all controversy. We want more data and more analysis.
But the preliminary indication is that if Mother Nature flipped a switch 25 years ago that reduced cloud cover and warmed the planet, it wasn’t us that did it, and presumably she could flip it back any time and we’d see a corresponding cooling, especially since we really don’t know what that switch actually was.
P.S. While we like sunny and warm weather more than cloudy and cool, it would be worth witnessing such a reversal just for the perverse enjoyment of seeing the climate crowd blame that too on ‘greenhouse gases’ and claim they’d actually predicted it all along.
Heck, why not another man-made global cooling scare?
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Herb Rose
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The higher the heat at the surface the more water evaporates. The evaporation of water from the surface removes 600 calories of heat per gram and takes it up to be released into space. Evaporation is cooling the Earth, not clouds.
Evaporation occurs at all temperatures as long as the humidity is not 100 %. If the level of water in the air is .22 % it is 50 times greater than the amount of CO2, which means every gram of CO2 must add 30,000 calories to the surface to keep the temperature constant. Even with a constant temperature, as long as the humidity is not 100 %, more water will evaporate. When the level reaches .33 % every gram of CO2 must now add 45,000 calories to the surface to compensate for the cooling by water and keep the temperature constant. If the surface is heating the CO2 and its temperature is the same, where does the CO2 get the additional 15,000 calories?
It is water that controls the temperature.
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Seriously
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It’s called SUMMER. And it can and has been warm thru October, hot days in November. Consider who’s taking Temps and where. Consider that we’ve covered vast areas with CONCRETE, ASPHALT. Consider that we are in the last stages of reaching the angle of spin known as the Age of Aquarius, slowly evolving spin that’s now reaching for it’s 25-26000 YEAR apex. Humans have been taking Temps, noting weather on their instruments for what, a little more than a hundred years? Hubris to decide a single drop of knowledge knows Anything of the earth and it rhythms over Billions of years. And it will be here long after we’ve snuffed ourselves out. There are cities underwater for the love of pete!! Guess we used to breath thru our gills…
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David Hamilton Russell
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Here are the only two things you need to know about global warming:
1) Summers are hot;
2) Some summers are hotter than others.
There you go. Easy-peasy.
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John V
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And usually, if a region is having warmer than average temps, somewhere in the world they are having cooler than avg temps.
In Chicago, when we would have – 10°F or colder days, Alaska was in the 30s and 40s. All that cold air flowed down due to the jet stream. Some days, Chicago is warmer in the late Spring/early Summer than we are here in Phoenix. It’s called weather.
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David Hamilton Russell
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So….
3) Rules 1 and 2 vary from place to place.
Still, easy-peasy.
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Jerry Krause
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Hi David and John,
First, David, welcome back. Both your comments are very good and informative. Thank you both.
Have a good day
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