The recent paper by Tselioudis et al., titled “Contraction of the World’s Storm-Cloud Zones the Primary Contributor to the 21st Century Increase in the Earth’s Sunlight Absorption”, is a fascinating—and deeply problematic—addition to the climate science canon. It offers yet another reminder that so-called “settled science” in climate modeling is anything but settled. In fact, it inadvertently illustrates how fragile the predictive power of climate models is, especially when fundamental atmospheric processes like cloud coverage are shown to be both more dynamic and less understood than previously claimed.
Not that any of this is news to WUWT readers. Dr. Roy Spencer has been noting almost identical observations for over a decade as noted here,
Now let’s look at the broader scientific community catching up to Dr. Spencer.
Abstract
Recent Earth energy budget observations show an increase in the sunlight absorbed by the Earth of 0.45 W/m2 per decade, caused primarily by a decrease in cloud reflection. Here we decompose the solar radiative budget trends into general circulation and cloud controlling process components. Regimes representing the midlatitude and tropical storm zones are defined, and the trends in the areal coverage of those regimes which are potentially induced by circulation changes are separated from trends in the cloud radiative effect within each regime which are potentially induced by changes in local cloud controlling processes. The regime area change component, which manifests itself as a contraction of the midlatitude and tropical storm regimes, constitutes the largest contribution to the solar absorption trend, causing decreased sunlight reflection of 0.37 W/m2 per decade. This result provides a crucial missing piece in the puzzle of the 21st century increase of the Earth’s solar absorption.
Key Points
- Satellite observations show that in the past 24 years the worlds storm cloud zones have been contracting at a rate of 1.5%–3% per decade
- This contraction allows more solar radiation to reach the Earth’s surface and constitutes the largest contribution to the observed 21st century trend of increased solar absorption
Plain Language Summary
Analysis of satellite observations shows that in the past 24 years the Earth’s storm cloud zones in the tropics and the middle latitudes have been contracting at a rate of 1.5%–3% per decade. This cloud contraction, along with cloud cover decreases at low latitudes, allows more solar radiation to reach the Earth’s surface. When the contribution of all cloud changes is calculated, the storm cloud contraction is found to be the main contributor to the observed increase of the Earth’s solar absorption during the 21st century.
To understand the full implications of this study, we need to parse its findings in plain terms. The paper concludes that the Earth has absorbed significantly more solar radiation over the past 24 years—0.45 W/m² per decade. The primary culprit? A reduction in cloud cover, specifically a contraction of the midlatitude and tropical storm-cloud zones. This change has resulted in less solar radiation being reflected back into space and more being absorbed by the Earth’s surface. Crucially, 0.37 W/m² of this uptick is attributed solely to this contraction in cloud coverage, a result of large-scale atmospheric circulation changes:
“This cloud contraction, along with cloud cover decreases at low latitudes, allows more solar radiation to reach the Earth’s surface. When the contribution of all cloud changes is calculated, the storm cloud contraction is found to be the main contributor to the observed increase of the Earth’s solar absorption during the 21st century.”
Let’s pause there. Climate science has long emphasized the role of anthropogenic greenhouse gases—especially CO2—in trapping outgoing longwave radiation, contributing to surface warming. Yet here we have empirical satellite observations showing that changes in shortwave radiation absorption, due to cloud dynamics, dominate recent trends in Earth’s energy imbalance. That revelation alone should be enough to shake the very foundations of climate policy, which has funneled trillions into carbon control with scant attention paid to cloud feedback mechanisms.
More damning still is the admission that these changes are likely tied to “general circulation shifts,” specifically poleward movements of storm tracks and contractions of the Intertropical Convergence Zone (ITCZ). These are phenomena long suspected in model projections but never given such a central, quantifiable role in the planetary energy budget. And here’s the kicker: these circulation shifts are said to have emerged gradually, to the tune of 1.3% to 3% per decade:
“In all three zones, the area coverage of the L‐TCC regime shows statistically significant decreases with extremes of 1.84 ± 0.38% to 3.20 ± 0.97% per decade… indicating a contraction of the midlatitude storm regions and a narrowing of the ITCZ region.”
These aren’t theoretical projections—they are based on hard satellite data from the MODIS and CERES instruments. Models, by contrast, have only roughly hinted at these changes, and often fail to reproduce them with consistency.
The paper outlines that most of the shortwave cloud radiative effect (SWCRE) change—the key measure of how much solar energy is reflected by clouds—comes not from changes in cloud properties themselves, but from the shrinking geographic area of major cloud regimes:
“In all zones, the dominant trend is the SW cloud radiative warming that is coming from the contraction of the S‐SWCRE regimes and the corresponding expansion of the W‐SWCRE regimes.”
That’s the kind of subtle, high-leverage feedback mechanism that models tend to get wrong or underrepresent entirely. And that’s a problem. Because if your model can’t accurately simulate cloud regime shifts—which appear to contribute more than 80% of the increase in solar absorption—then your forecasts for future warming are at best incomplete, and at worst, wildly misleading.
Tselioudis et al. even admit this shortcoming, noting:
“It is imperative to test the skills of climate models in simulating the observed storm‐cloud area contraction, and to use both modeling and observational analyses to understand the interactions between atmospheric dynamics shifts and storm cloud changes.”
That’s bureaucratese for “we didn’t see this coming, and we’re not sure our models can catch up.” It’s reminiscent of NASA’s Gavin Schmidt’s recent handwringing over 2023’s “unexplainable” heat spike, suggesting that “we could be in uncharted territory.” Now, we have the chart. And it doesn’t point toward CO2 alone—it points to dynamic, cloud-driven changes that no carbon tax will stop.
What this paper also inadvertently confirms is the unreliability of using long-term climate models to dictate aggressive, disruptive policies like Net Zero. The models are missing key physical processes—cloud behavior, aerosol effects, and large-scale atmospheric shifts. As the paper notes:
“The general circulation shift component constitutes the dominant term of the recent increase in absorbed solar radiation and provides a crucial missing piece in the puzzle of the 21st century radiative warming and the large heat anomaly of 2023.”
Yet these shifts are only just beginning to be understood, and their driving forces—whether natural variability, solar activity, ocean cycles, or some interaction thereof—remain far from nailed down.
Worse still, the authors openly speculate that low-latitude cloud reductions could be driven by aerosol changes—particularly the decline in ship emissions:
“This component shows a significant cloud radiative warming of 0.21 W/m²/decade that can be attributed to aerosol indirect effects on clouds including effects from the reduction of aerosol ship emissions.”
That’s right: the same well-meaning efforts to reduce pollution from ocean-going vessels may have accelerated warming by allowing more sunlight to hit the surface. Climate mitigation whack-a-mole strikes again.
In sum, Tselioudis et al.’s paper is a quietly revolutionary work—not because it introduces a new alarmist narrative, but because it destabilizes the prevailing one. It shows that:
- Cloud feedbacks, especially those driven by circulation shifts, have enormous and previously underestimated impacts on Earth’s radiative balance.
- These changes are driven by complex, poorly understood dynamics that current climate models struggle to replicate.
- Policy decisions predicated on “settled science” have been made in the absence of understanding a major component of the Earth’s energy system.
If climate science were a functioning scientific discipline rather than a priesthood, this paper would trigger a major course correction. It would cast doubt on the simplistic link between CO2 and warming, redirecting focus toward cloud physics, ocean-atmosphere interactions, and circulation dynamics. It would foster humility in the face of atmospheric complexity—not arrogance born from model outputs.
But don’t expect that anytime soon. Instead, expect the usual suspects to spin this as evidence of “even worse than we thought” warming, conveniently omitting the part where their models didn’t predict it and their policies had nothing to do with it.
In the meantime, this paper should serve as ammunition for any skeptic pointing out the absurdity of building trillion-dollar policies on the backs of incomplete and overconfident simulations. The cloud regimes are shifting. The models aren’t keeping up. And neither is the narrative.

Hard not to laugh at the affect of imposing more expensive bunker fuel on shipping has been to make the planet warmer. If it was really about the planet then we should go back to the cheaper fuel.
The actual cause of the reduced cloud cover is the reduction in the amount of industrial SO2 aerosol pollution in our troposphere, due to American and European “Clean Air” legislation in the mid 1970’s, and later, also from Net-Zero activities.
SO2 aerosols are microscopic droplets of Sulfuric Acid, H2SO4, which has a VERY strong affinity for moisture, sometimes being used as a drying agent.
As their level in the atmosphere is reduced, there are fewer moisture nucleation sites, and thus, fewer clouds, and increased warming..
This is inevitable, meaning that all of our modern (since 1980) warming has been man-made!
Unfortunately, SO2 aerosol pollution levels have been reduced to the point where more warming will occur, even if all Clean Air and Net-Zero activities are immediately halted. An additional increase of 1.5-2.0 C can be expected, causing millions of heat-related deaths.
The cleaner the air, the hotter it will get!
This could be temporarily delayed, if there are any VE!4 or larger volcanic eruptions to inject SO2 aerosols into the stratosphere, or the burning of fossil fuels from increased industrial activity..
Plants also emit aerosols that help with cloud formation.
Oceans, too.
Sparta Nova 4:
Yes, although SO2 aerosols far exceed their effects.
That may be true, but I have seen nothing that validates and verifies that.
I’ve looked at clouds from both sides now
From up and down and still somehow
It’s cloud illusions I recall
I really don’t know clouds at all.
— Joni Mitchell, 1966
From the above article;
“To understand the full implications of this study, we need to parse its findings in plain terms.”
So true. But to fully appreciate the irony present, please note the article’s subject paper is titled Contraction of the World’s Storm-Cloud Zones the Primary Contributor to the 21st Century Increase in the Earth’s Sunlight Absorption . . . the title dare not state the overriding conclusion that an increase in sunlight absorption logically results in “global warming” because that would be contrary to the established meme that it is increasing CO2 that is the predominate “driver” of global warming climate change.
It is interesting—but no surprise to me—that the “Abstract”, “Key Points” and “Plain Language Summary” (hah!) quoted from the referenced article all fail to mention either “global warming” or “climate change”. Had the paper’s authors done either, I have no doubt the scientific article would never have been published by Geophysical Research Letters.
“I have no doubt the scientific article would never have been published by Geophysical Research Letters”
Again, wearily, this paper is from GISS researchers who have published many similar papers over the last three decades. They follow the good scientific practice of sticking to topic, and writing only what they actually have results about. I am sure they are well aware that the reduction in low level storm clouds is part of a global warming feedback.
I’ll wearily point out that past performance is no guarantee of current (or future) results. And quantity does not correlate to quality . . . of all WUWT posters, you should be well aware of this, but alas!
You appear to have totally missed my point that those very authors did NOT go so far as to (a) mention “global warming” as I noted in my previous comment, and (b) did not dare to suggest that their noted reduction(s) in global cloud coverage may be of much greater significance than mankind’s CO2 emissions in terms of causing global warming.
In considering this last point, the above WUWT article correctly points out that this realization merits the description of being a “bombshell” (of likely truth) confronting all AGW/CAGW alarmists!
“More damning still is the admission that these changes are likely tied to “general circulation shifts,” specifically poleward movements of storm tracks…”
A warmer North Atlantic (AMO) drives the decline in low cloud cover, the warmer AMO is driven by negative North Atlantic Oscillation (NAO) regimes, i.e. 1995-1999 and 2005-2012. The North Atlantic marine heatwave of 2023-2024 was again driven by negative NAO states, causing a further decline in low cloud cover, Referring to negative NAO as “poleward movements of storm tracks” is rather obfuscatory.
Low cloud cover has declined since 1995:
As for claims that global warming has driven the decline in cloud cover, rising CO2 forcing in the global circulation models is predicted to increase positive NAO states, which can only drive a colder AMO. But the AMO is always warmer during centennial lows in solar activity!
https://archive.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-3-5-6.html
I just went outside and looked up.
It is hotter today than yesterday and yet there are more clouds in the sky today.
Large body of water some 5+ miles to the east.
I went outside today in the morning. No clouds. It got hotter. Now there are clouds.
I guess that proves that hotter air suppresses cloud formation.
/sarc
This morning, I had posted the actual cause of our reduced cloud cover, which has been overlooked by others, but checking for comments just now, I find that the post has disappeared!
I was not aware that WWUT censors comments.
{N.B.: WUWT, not WWUT)
I believe they actually do that—unashamedly—in the case of postings of spam.
This wouldn’t be a contrived report to justify atmospheric geoengineering?
This is a re-post of my earlier one that disappeared. I wonder how it will fare!
The actual cause of the reduced cloud formation now being observed is the reduction in the amount of industrial SO2 aerosol pollution in our troposphere, caused by the American and European “Clean Air legislation in the 1970s to reduce their levels, and also, more recently, “Net–Zero” activities to ban the burning of fossil fuels.
SO2 aerosols are microscopic droplets of Sulfuric Acid, which have a VERY strong affinity for moisture, and it is sometimes used as a drying agent.
Industrial SO2 aerosol pollution levels finally began falling in 1980, and temperatures began rising because of the less polluted air.
With fewer SO2 aerosol moisture nucleation sites available, fewer clouds are formed, which also contributes to the global warming, now probably the major amount..
For the year 2023, the amount of cooling industrial SO2 aerosol pollution in our atmosphere was reported to be only 69 kilotons, about one-third of that from a VEI4 volcanic eruption, so that the major warming now comes from reduced cloud formation.
In the absence of any VEI4 or larger volcanic eruptions to introduce SO2 aerosols into the stratosphere, or increased industrial SO2 aerosol emissions, or repeal of the low-sulfur mandate for maritime shipping, temperatures will continue to rise to roughly 1.5-2 C above current temperatures.
Millions will die because of the high temperate-related disasters. Geo-engineering might help..
When I see the word: Bombshell, I proceed to the next article.
Interesting.
All of the comments after the morning of July 25 have disappeared.
More censoring??