RCP 8.5: When the Spherical Cows Escape the Barn

A scenario the modelers built as a stress test became, for fifteen years, the scenario the press treated as your future. It has now been quietly retired. The reckoning has not yet begun.

From Watts Up With That?

By Charles Rotter

A scenario the modelers built as a stress test became, for fifteen years, the scenario the press treated as your future. It has now been quietly retired. The reckoning has not yet begun.

There is an old joke in physics. A dairy farmer hires a theoretical physicist to improve milk production. The physicist disappears for six months, returns with a 200-page report, and announces: I have a solution. It works for spherical cows in a vacuum.

The joke endures because every physicist has met the spherical cow. To make a hard problem tractable, you strip the real world down to a geometry the math can handle. A round, frictionless object floating in nothing is something you can actually compute. A real cow is not. The simplifying assumption is a tool. useful inside the laboratory and the seminar room, useless the moment it walks out the door.

RCP 8.5 was a spherical cow. For fifteen years it walked out the door, into headlines, into government reports, into court filings, into bank stress tests, and into the climate fears of hundreds of millions of people who had no idea what it was. As of April 2026, the international committee that produces the official climate scenarios for the United Nations has quietly walked it back into the barn and shut the door behind it.

The retirement, in the form of a footnote

On April 7, 2026, Geoscientific Model Development published van Vuuren et al. 2026, the design paper for the next round of climate model scenarios, the inputs that will feed the IPCC’s Seventh Assessment Report (AR7) and the climate research of the rest of the decade. Buried inside is the verdict that closes the book on a decade and a half of climate communication: in the authors’ own characterization,

the CMIP6 high emission levels (quantified by SSP5-8.5) have become implausible.

That is the formal obituary, written by the same scientific community that wrote the birth certificate. The new CMIP7 framework eliminates the three extreme scenarios, RCP 8.5, SSP5-8.5, and SSP3-7.0, that have dominated climate research, climate journalism, and climate policy since the early 2010s.

The announcement was met, in the English-language press, with a silence so complete that Roger Pielke Jr., who has been documenting the misuse of these scenarios in the peer-reviewed literature for years, spent the first two weeks of May simply cataloging which mainstream outlets had not yet covered the story. The list was nearly all of them. Coverage finally arrived, more than a month after publication, only when the President of the United States posted about it on social media. The New York Times, the Washington Post, the AP, Bloomberg, and Carbon Brief then all ran stories within forty-eight hours, most of them framed around the President rather than the science, and most repeating the same factual errors about what RCP 8.5 had ever been.

To understand why that matters, you have to understand what RCP 8.5 actually was, and what it was not.

What it was: a high-signal input for a noisy machine

From a constructive discussion elsewhere with a leading climate modeler, a comment that helps us to better understand how we got into the scenario mess. I agree 100% with his comment:

“From a modeling side, most of us really do not care much (or do not know about) the…— The Honest Broker (@RogerPielkeJr) May 21, 2026

The cleanest description of what RCP 8.5 was built for came from an unnamed climate modeler quoted recently by Pielke. Asked why the extreme scenario became so dominant in model intercomparison runs, the modeler explained that most modelers do not pay close attention to the socioeconomic assumptions underlying any given scenario. What they need is an input that drives a climate model. In the modeler’s words:

a higher signal is better from a signal/noise perspective.

At ten to a hundred thousand dollars per model run, a higher-emissions scenario produces a cleaner climate signal you can analyze. Lower scenarios require many more runs to pull the signal out of the natural variability. Choices have to be made.

In other words, RCP 8.5 was useful to physical climate modelers in roughly the same way the spherical cow is useful to a graduate student studying angular momentum. It made the math tractable. It was never meant to be a forecast. It was a stress test, a deliberately extreme number you plug in so you can compare model outputs and study the climate system’s response to a large radiative forcing.

The original 2011 paper that introduced RCP 8.5 (Riahi et al. in Climatic Change) said as much: a baseline at the upper end of the published literature, assuming a roughly sevenfold expansion of global coal use through 2100, a population trajectory at the high end of UN projections, and effectively no technological progress in low-carbon energy. Even at the time, this was understood to be an outlier. Keywan Riahi, the lead author, now tells Seth Borenstein of the Associated Press:

it was never a likely case.

Zeke Hausfather, on a recent panel hosted by Andrew Revkin, conceded essentially the same thing, that the 2011 energy modeling literature had been clear about what RCP 8.5 was: a high-end statistical bookend, not, as he put it,

a particular likely outcome.

If that is what Riahi and Hausfather believe now, and what the literature said in 2011, it raises a question. Why was Riahi’s scenario quietly promoted from “outlier baseline” to “business as usual” in the IPCC’s Fifth and Sixth Assessment Reports, in the U.S. National Climate Assessment, in central bank stress tests, and in fifteen years of climate journalism?

And why did nobody, at any of those institutions, including the modeling community itself, shout?

The cow escapes

The transformation from stress test to forecast happened by gradual institutional drift, not by deliberate decision. The IPCC’s Fifth Assessment Report in 2013 designated RCP 8.5 as the reference scenario. Once a generation of impact studies, vulnerability assessments, and policy papers had been written under that assumption, the IPCC’s Sixth Assessment Report in 2021 inherited a body of literature so saturated with RCP 8.5 that disentangling it was no longer possible. The Sixth Assessment included mealy-mouthed language acknowledging the scenario was unlikely while continuing to feature it prominently throughout.

By that point, RCP 8.5 had become the implicit baseline for almost everything readers were being told about the climate future. It was the source of nearly every “by 2100” headline of the past decade. According to Pielke’s accounting, RCP 8.5 accounted for over half the scenario references in the 2018 U.S. Fourth National Climate Assessment, around sixty percent in the IPCC Special Report on the Ocean and Cryosphere, and roughly a third of all RCP references in the IPCC AR5. By early 2020, peer-reviewed studies invoking it were appearing at a rate of roughly twenty per day. So far in 2026, even after the formal retirement, they are appearing at thirty per day.

This was not an obscure technical artifact. It was the engine of the climate-alarm story for a generation.

It also became the basis of policy. Pielke’s tabulation runs to dozens of pages. National climate impact assessments in the United States, the United Kingdom, Germany, Canada, Australia, Japan, and the Netherlands all use RCP 8.5 or SSP5-8.5 as a reference scenario. The Network for Greening the Financial System framework, used by more than 140 central banks, built its “Hot House World” stress test on it, which then flowed into the bank capital tests run by the European Central Bank, the Bank of England, the U.S. Federal Reserve, and others. The World Bank’s Climate Change Knowledge Portal, which produces the climate inputs for Country Climate and Development Reports in more than 100 nations, defaults to SSP5-8.5 and SSP3-7.0. The pending climate-damages lawsuits against U.S. energy producers, including Multnomah County’s $51 billion claim, are built on damage projections derived from RCP 8.5 modeling.

And during all of this, prominent voices in the climate establishment were not quietly hedging. In a 2021 forum reply published in Issues in Science and Technology, Chris Field, co-chair of IPCC Working Group 2 for the Fifth Assessment, and Marcia McNutt, then president of the National Academy of Sciences, defended the description of RCP 8.5 as a “business-as-usual” pathway as something that, in their words,

remains 100% accurate.

That sentence, by the official position of the scenario community that designs these things, is now false.

Where were the modelers?

The deepest question this retirement raises is not how RCP 8.5 was built. Its construction was always documented in plain sight; anyone willing to read the 2011 Riahi paper could see what it assumed and why. The question is why the people who built it, and the people who used it, sat in silence for fifteen years while it was bastardized.

The modelers were not deceived. They knew what they had made. They knew the difference between an exploratory high-forcing case and a forecast. Hausfather himself, in the same panel discussion cited above, acknowledged that the 2011 energy modeling literature was clear about what RCP 8.5 was. The information was never hidden. It was simply ignored, first by the impact community, then by journalists, then by central bankers, then by federal courts. And the people who knew better said nothing.

Consider the moments at which speaking up would have mattered.

When the IPCC AR5 made RCP 8.5 the reference scenario in 2013, the modeling community had standing to object. They did not. When the U.S. National Climate Assessments of 2014 and 2018 built their headline projections on it, the scenario authors had standing to clarify. They did not. When central banks began constructing stress tests around a “Hot House World” calibrated to RCP 8.5, the scientists whose work was being repurposed for bank capital regulation had standing to push back. They did not. When the IPCC AR6 in 2021 again featured RCP 8.5 throughout its assessment, while including buried language warning that it had become unlikely, the lead authors could have insisted on a clearer correction. They did not.

When Roger Pielke Jr. and Justin Ritchie published their formal diagnosis of scenario misuse in Energy Research & Social Science in 2021, the response from senior figures in the climate establishment was not gratitude for a needed correction. It was, in the case of Field and McNutt, an active defense of the indefensible. Pielke and Ritchie spent the next five years being characterized in mainstream coverage as marginal critics rather than as the people who had been correct all along.

Distorting the view of our climate future: The misuse and abuse of climate pathways and scenarios – ScienceDirect

The few who did speak up, Pielke, Ritchie, Matthew Burgess, Steven Koonin, Richard Tol, and a small handful of others, paid the social and professional costs of speaking up. The much larger group that knew, and stayed quiet, did not pay those costs. They are now, in May 2026, beneficiaries of a course correction they did not lead and a quiet retirement that contains no admission of error.

This is not a story about scientific fraud. It is a story about institutional cowardice and the sociology of a discipline whose career incentives, funding pipelines, and journal access were aligned with letting a false framing run unchallenged. The technical scientists who could have stood up at any point during the past decade and said this is not what our scenario means, and made that clear in the public square, not just in cautious footnotes, did not do so. The professional cost of being branded a “denier” was apparently too high; the cost to the public of letting the bastardization continue was paid by someone else.

Pielke writes that science is self-correcting. On a long enough timeline, that is true. But science self-corrects through the work of individuals willing to take the personal risk of contradicting a consensus, not through the passive accumulation of new data inside a silent profession. The reckoning here is not just that RCP 8.5 was wrong. It is that the modeling community knew, and waited, and is now being credited with a correction that arrived only after the costs of denial had become higher than the costs of admission.

The reckoning that hasn’t started

What does it mean, in practice, that the foundation has now been declared unsound?

Every reader of this site has spent fifteen years being told, in increasingly dire language, what the climate of 2100 will look like. A great deal of that language was downstream of RCP 8.5. The 2026 retirement does not erase those projections from the journalistic record, but it does change how a thoughtful reader should weigh them on the way back through the archive. The “by 2100, coral reefs collapse” story; the “by 2100, the U.S. economy shrinks ten percent” story; the “by 2100, ice-free Arctic, climate refugees, mass extinctions, civilization-threatening heat” stories, a substantial fraction of these were the spherical cow’s footprints across the cultural landscape.

The new CMIP7 framework brings the high end of the scenario set down considerably. Pielke’s apples-to-apples comparison using the FaIR climate emulator finds the new HIGH scenario produces about 0.9°C less warming than SSP5-8.5 by 2081–2100. Compared to the IPCC AR6’s projection of SSP5-8.5, the gap widens to about 1.4°C. The implausibility of the upper-end legacy scenarios, in his phrase, means

the future is not what it used to be.

But the cleanup is not complete, and on this point the WUWT reader should pay close attention to where Pielke and the official scenario community part company. Three observations matter.

First, the new HIGH scenario is itself still implausible by the standards Pielke and his coauthors have proposed in the peer-reviewed literature. It inherits the SSP3 storyline, including a 2100 global population the IIASA recently revised upward to 14.5 billion, a number that exceeds every contemporary demographic projection and is driven primarily by an assumed 35% upward revision in Africa’s 2100 population.

Second, the new MEDIUM scenario, which van Vuuren et al. describe as a current-policy trajectory, produces higher cumulative emissions through 2100 than the IEA’s current-policy scenario produces by 2050. On the IEA’s own numbers, today’s policy trajectory delivers roughly 2.5°C of warming by 2100. The new MEDIUM delivers more. Calling it a “current policy” scenario is, charitably, a stretch.

Third, the mainstream coverage that finally arrived in May was not a reckoning. The first wave of New York Times, Washington Post, AP, Bloomberg, and Carbon Brief coverage uniformly described RCP 8.5 as the “worst-case” scenario (it was a baseline scenario), attributed its retirement to the success of renewable energy policy (it became implausible because its core assumptions about coal expansion and demographic trends were always wrong), and framed the story around President Trump rather than around fifteen years of institutional error. Pielke’s verdict on the coverage, in his most recent post: the outlets that built years of stories on RCP 8.5 chose to

minimize and deflect.

The lesson

The lesson here is not that climate scientists were stupid or dishonest. The modelers who pulled RCP 8.5 off the shelf because it gave them a clean signal were doing what physical scientists routinely do. It is their subsequent lack of action to correct the record as necessary that screams monumental cowardice. The spherical cow has its place. The trouble begins when the spherical cow is wheeled out of the lab and presented to the public as if it were a real cow, and then wheeled into the Federal Reserve and presented to bank regulators as the cow you should be valuing your loan book against, and then wheeled into a federal courthouse and presented to a judge as the cow whose damages an energy company should be required to pay.

That is what happened. The official scenario community has now admitted, in the formal scientific literature, that the cow was not a cow. They have done so in a footnote, with no apology, after a decade and a half of silence from the broader profession that knew, or could have known, all along. The press that built a generation of front-page stories on it has so far chosen not to notice.

The next time you read a headline about climate change and the year 2100, whether it appears in the New York Times, in a central bank report, or in a complaint filed in federal court, the first question to ask is which scenario the projection rests on. If the answer is RCP 8.5 or SSP5-8.5, you are reading about a spherical cow.

The barn door is shut. The cow has gone back inside. What remains is the trail of damage it left while it was out, and an open question about why so many people in a position to stop it kept walking past the open door.

Footnote: At this point it is safe to say the climate models are moooot. [Anthony]

Fusion Fantasy (Nature Energy report)

Fusion energy — yielding enormous amounts of heat from the violent combination of elements — has long been touted as the holy grail of energy future. That’s wrong, according to a new article in the prestigious Nature Energy.

From Master Resource

By Kennedy Maize

“All the recent flurry of fusion fascination prompted one long-time observer of the story to quip, anonymously, ‘The folks who brought us the most expensive way in the world to boil water, fission, now want to double down with fusion.’”

“While nuclear fusion power is often hailed as a future source of abundant, clean energy, current dominant fusion designs, magnetic and laser inertial, are unlikely to become competitive due to their expected low experience rates,” concludes the article by a team of researchers led by Lingxi Tang of the Energy and Technology Policy Group, Swiss Federal Institute of Technology in Zurich.

The policy implication? “[P]olicymakers should not rely on, or fund, fusion power as a core pillar of future clean energy systems unless designs with different characteristics are developed.”

Analysis

The article focuses on the current mainstream approaches to fusion — combining atoms through magnetic confinement or laser-induced confinement — concluding that they are “inherently large in unit size, extremely complex in design, and require moderate to high customization.”

Estimates of fusion’s costs, based on their research, range from $1,400 per kilowatt to $43,000 per kilowatt. These wildly divergent estimates lead the researchers to conclude that

fusion power is likely to remain uncompetitive relative to other low-carbon electricity supply technologies. This casts considerable doubt on the future role of fusion power in a net-zero energy system and whether current investment levels from both the public and private sectors are justified.

The article is a direct shot at the long-running, often-troubled, multi-billion-dollar, 34-nation ITER project in France. The “International Thermal Energy Reactor” project, the tokamak magnetic confinement machine, has been under construction since 2013 and now hopes to achieve its first plasma in 2036.

The analysis also targets the Department of Energy’s National Ignition Facility at Lawrence Livermore National Laboratory in California. In 2022, researchers were able to use focused lasers to achieve “break even,” producing more power output than the energy input by a tiny margin. That event generated a lot of publicity and optimism at the time, but little has been heard from Livermore since.

More recently, several startups claiming they are on the cusp of achieving practical fusion energy have raised a lot of venture capital, without actually delivering energy. All aim for smaller projects, with potentially multiple sales. None have reached the point of having a licensing proceeding at the U.S. Nuclear Regulatory Commission, a requirement before they can be commercially deployed.

Among them:

Helion Energy, based in Everett, Wash., founded in 2013. The company claims it has a smaller approach to fusion, which it terms “aneutronic fusion,” minimizing the production of neutrons with a pulsed linear magnetic confinement technology. It has backing from Open AI’s Sam Altman. The company has a 2023 agreement with nearby Microsoft to supply 50 MW of power in 2028 for a data center.

Commonwealth Fusion Systems, a Boston spin-off from MIT’s fusion energy program, developing a down-sized tokamak using high-temperature superconduction magnets to, the company claims, lead to “high performing, fusion systems at significantly lower cost.”

The company has a deal, details unspecified, with Google, an investor, for “an offtake agreement for 200 megawatts (MW) of clean fusion power” in Chesterfield County, Virginia.

General Fusion, headquartered in British Columbia, with subsidiaries in the U.S. and the U.K., and founded in 2002. The company’s technology, magnetized target fusion, combines both conventional approaches to achieving high-temperature plasma as a fusion starting point. In January, the company announced it is going public on the NASDAQ through a deal with a special purpose acquisition company, Spring Valley Acquisition Corp. III, to eventually become listed as NASDQAQ:GFUZ.

TAE Technologies, based in California and founded in 1998. The company bases its fusion technology on a hydrogen-boron process, known as known as proton-boron or p-11B. rather than the conventional merging of hydrogen isotopes deuterium and tritium. This reduces production of neutrons. It aims for a prototype commercial reactor by 2030, which it plans to be in the 350–500 MW scale. The company recently merged with the Trump family’s Trump Media and Technology Group Corp. with a self-proclaimed value of $6 billion and a CNN warning of “serious ethics concerns.”

Conclusion

The recent flurry of fusion fascination prompted one long-time observer of the story to quip, anonymously, “The folks who brought us the most expensive way in the world to boil water, fission, now want to double down with fusion.”

Always controversial and often outrageous commentator and mega-billionaire Elon Musk, no friend of fusion, commented on Twitter last December:

The Sun is an enormous, free fusion reactor in the sky. It is super dumb to make tiny fusion reactors on Earth. Even if you burned 4 Jupiters, the Sun would still round up to 100% of all power that will ever be produced in the solar system!!

Investors and public policy experts should heavily discount fusion hyperbole. Nuclear fission for new capacity is full of challenges–nuclear fusion has far more ground to cover.

CERES Albedo

CERES data has been widely discussed in climate research because even small changes in reflectivity can alter Earth’s energy balance measurably over time.

From Andy May Petrophysicist

By Andy May

Albedo (or Earth’s global reflectivity) in this post is defined as the amount of solar shortwave (SW) radiation that the Earth reflects into space, as measured at the top of the atmosphere or TOA, divided by the total solar radiation reaching Earth also measured at the TOA.

In the CERES EBAF satellite context (Loeb et al., 2009, 2018, 2021), and using their variable names, this is toa_sw_all_mon divided by solar_mon, where “mon” means monthly and “sw” means shortwave radiation. In this post we compute yearly global latitude-area-weighted means from the monthly values for most of the illustrations to avoid seasonal effects, which are very large. As seen in figure 1, there is a distinct albedo peak that falls roughly between 2004 and 2007 and afterward the albedo falls until 2025, with a second smaller, but still dramatic peak in 2020.

Figure 1. Upper left: the area-weighted global mean outgoing shortwave radiation at the TOA (W/m²). Upper right: the computed albedo as a percent. Lower left: Outgoing longwave emissions from Earth (W/m²). Lower right: surface shortwave absorption (W/m²). To see this and the other figures in higher resolution click on the figure.

Nearly all CERES EBAF variables show an anomaly during the 2004-2007 albedo peak, which falls in the middle of the famous pause in global warming. Notable exceptions are the cloud radiative effect (CRE) variables. The albedo peak anomaly, at least according to CERES EBAF, does not appear to be a cloud feature, but a surface feature.

I need to mention here that CERES EBAF variables have been adjusted, at the TOA, so that the Earth Energy Imbalance (EEI) equals that calculated from changes in ocean heat content. This is explained further in another post. Thus, the measurements in this post are not raw satellite measurements but are from a model.

It is interesting that the emitted longwave radiation at the TOA (lower left, figure 1) is also anomalous during this peak. LW (longwave) downwelling radiation is high in this period, but shows no distinct anomaly, as would be expected if cloud cover caused the albedo anomaly. All the trends given in the figures are ordinary least squares (OLS) linear trends.

Solar incoming SW

Figure 2. Upper left: the total incoming solar SW by month in blue, and the monthly anomaly in red. Upper right: only the monthly anomaly incoming SW. Lower left: the yearly averaged solar incoming SW. Lower right: the trend in solar incoming SW from 2001-2025. Notice that solar incoming SW radiation is decreasing in the Northern Hemisphere and increasing in the Southern Hemisphere, the zero contour falls at about 7°N. The numbers and bars in the plots identify the solar cycles.

The increasing solar SW in the Southern Hemisphere in figure 2 is due to changing orbital precession, as explained in figure 4 in this post. Figure 2 is intended to show how small the solar cycle signal is in comparison to seasonal effects. The cycle is extracted by creating 2001-2025 monthly insolation means and then subtracting them from each respective monthly mean. The lower left graph shows the calendar year average solar SW at the TOA. The solar cycles are barely visible in this graph, but it shows the increasing insolation trend from around 2004 to the solar cycle 25 peak. Clearly over small time periods it is not a good idea to conflate solar cycles with insolation.

Comparing figures 1 and 2, we can see that reflected SW is a function of changing albedo and not incoming radiation changes. However, absorbed SW (lower right figure 1) at the surface does track the changing annual insolation (lower left, figure 2), as expected. I was a bit surprised that outgoing LW increased during the albedo peak. One of my earlier posts explains that the net TOA radiation (positive inward, toa_net_all) which is equal to the inward solar radiation in (figure 2) minus the toa_sw_all minus toa_lw_all (both from figure 1) can be used to compute an estimate of ECS. Computing ECS (equilibrium climate sensitivity to CO₂) from observations necessarily assumes all other factors do not change over the measurement period. This is clearly not true over this 25-year measurement period. Thus, albedo changes (regardless of the reason) affect any ECS estimate made.

Clouds

The short-term change in albedo seen in figure 1 could be assumed to be due to changing cloud cover and cloud characteristics. The CERES EBAF variables related to clouds are summarized in figures 3 and 4.

Figure 3. Upper left: global mean cloud area. Upper right: global mean cloud pressure and altitude. Lower left: global mean cloud temperature. Lower right: map of mean cloud area.

Figure 3 shows the global cloud area, cloud top pressure and temperature, and a map of global mean cloud area per grid cell. The remaining variable is the cloud optical depth or tau (τ), which is shown in figure 4.

Figure 4. Cloud Tau (τ) or optical depth. The upper graph is the change in tau by year and the lower map is a map of mean tau for 2025. As τ increases, cloud brightness and the amount of reflected sunlight increases, which increases surface cooling.

As the graph in figure 4 shows, the long-term trend in τ is zero, although there is an unremarkable peak within the albedo peak period. Oddly, while the albedo peak shows distinctly in most CERES EBAF variables, it is high but unremarkable in the cloud-specific variables. It coincides with a longwave toa-out anomaly as shown in figure 1, as well as a matching surface upwelling longwave anomaly that is not shown (see the PowerPoints slides linked at the end of this post for details). It also falls in a surface downwelling SW anomaly.

It is important to mention that the lack of a cloud anomaly in the albedo anomaly period does not necessarily mean one does not exist. The CERES cloud variables rely heavily on MODIS and are not computed solely in the general CERES EBAF inversion. The MODIS data has had problems with cross talk and drift as explained in Moeller and Frey, 2017 (see their figure 1). So, we cannot exclude the possibility that the CRE variables during the albedo anomaly period have data or processing problems that do not affect the other variables.

Surface

The remaining set of CERES EBAF variables are the surface or “sfc” variables. I do not think any of the CERES EBAF surface variables are measured, they are all modeled, especially the upwelling and downwelling SW variables. Two surface SW variables, the SW reflected by the surface under clear skies and all skies, are shown in figure 5. The albedo anomaly shows up prominently in these graphs, unlike in the cloud graphs.

Within the CERES-EBAF framework, the albedo anomaly appears in surface-related variables rather than cloud variables. Whether this reflects a physical surface change or a data processing artifact remains unclear. The variable sfc_net_sw is the net downward SW flux and it should reflect the albedo anomaly as a dip, which it does as shown in figure 6.

Figure 6. Top: Area-weighted net downward SW to the surface. The albedo peak shows as a negative anomaly as expected. Bottom: The cell-by-cell trend in net downward albedo. The trends are small and no map pattern emerges.

The variable graphed in figure 6 has two components and is equal to: sfc_sw_down_all – sfc_sw_up_all. The means of these two variables are shown in figure 7.

Figure 7. The upper graph is the surface global mean reflected SW and the lower graph is the total incoming SW at the surface. The difference (incoming – outgoing) is shown in figure 6.

Both the surface incoming and reflected SW graphs show anomalies in the albedo peak period, but they are offset with the incoming anomaly occurring earlier. The incoming anomaly coincides with a yearly mean solar minimum and the trend in the incoming SW graph in figure 7 is unsurprisingly similar to the incoming solar radiation shown in figure 2. The upper reflected SW graph is similar in magnitude (~0.3 W/m²) and shape to the albedo peak shown in figure 1. Thus, just as Earth approached the solar cycle 23/24 minimum, the surface albedo increased anomalously. I cannot explain this but find it very interesting.

Without this information, one would think that the albedo peak between 2004 and 2007 was due to a change in cloud cover, but we see no cloud cover anomaly at that time. The most visible anomaly is the surface albedo anomaly, and it shows up in the SW data and in LW data. The next obvious suspect is a change in sea ice, but the NSIDC data shows no anomaly at that time as shown in figure 8.

Figure 8. National Snow and Ice Data Center (NSIDC) global sea ice area in millions of square kilometers. The period from 2004 to 2007 shows a reduction in sea ice, which is the opposite of what we expect.

n fact, the albedo peak from 2004-2007 shows a reduction in global sea ice area, which is the opposite of what we expect. Albedo anomalies can arise from snow cover, vegetation changes, or regionally. Figure 8 shows just one of many possible surface variables that could have caused the anomaly.

CERES-EBAF Computation Anomalies

Most of the CERES-EBAF variables match the descriptions in the documentation, but there are some exceptions. Two are highlighted in figure 9.

Figure 9. According to the documentation, the total cloud effect (sfc_cre_net_tot) should equal sfc_cre_net_lw + sfc_cre_net_sw, but their annual global means do not match. Likewise, sfc_cre_net_sw should equal sfc_net_sw_all (skies) – sfc_net_sw_clr_t (the total grid cell cloud-free incoming SW) but does not.

The difference between the total supplied surface cloud radiative effect (CRE) and the value computed from summing the net lw and sw at the surface is large, 1.47 W/m². Although the variable sfc_cre_net_sw is part of the definition of sfc_cre_net_tot, the difference between net_sw_all (skies) – net_sw_clr_t (clear sky for the total cell area) and sfc_cre_net_sw is different and smaller than the first difference.

Another odd documentation problem is the definition of toa_cre_sw. It is defined as “all-sky flux minus clear-sky (for total region) flux.” Using CERES EBAF variable names, that is, toa_sw_all – toa_sw_clr_t, yet the value in the EBAF file is the negative of the value defined. Toa_sw_all (outgoing all-sky SW) is always larger than toa_sw_clr_t, thus the definition defines a positive number, not the negative sw_cre_sw we see in the EBAF dataset. Incoming SW (solar_mon in figure 2) at the TOA is the solar flux coming in, the values whose name begins with “toa_sw” are all supposed to be positive outgoing flux. Thus, toa_sw_all will always be larger than toa_sw_clr_t and toa_cre_sw should be positive using the definition, but what we get is a negative number. This is OK, but the documentation should be fixed.

All these problems were reported to the CERES EBAF team on May 18. I received an acknowledgement that they received my email and their opinion on the smaller sfc_cre_net_sw discrepancy. I asked about the larger problems by email, but was told the critical person needed to answer my questions was on vacation. If I get a reply on these issues, I will update this post and put up a separate post letting all of you know what the CERES team says. I don’t think I need to wait, as I have investigated all this in every way I can imagine at this point.

They think the smaller sfc_cre_net_sw problem might be due to computational differences in how the area-weighted global means are calculated. Perhaps, but as you can see in the supplementary information to this post (link below), all other computational cross checks of the 41 CERES EBAF variables match to two or more decimal places. One can reasonably ask, why do these two exceptions exist?

As a further check, I ran a program against the data to look for missing grid cell values, thinking that if some of the variables had missing values in some cells and others did not, that could cause the discrepancy. I only found one variable that had any missing cell values: sfc_cre_net_tot_mon, which is the surface CRE net total (downward) radiation flux variable. It had 10 missing values in the 25 years examined and it was the only variable with any missing values. Each year of each grid has 64,800 grid cells, so one in 64,800 is nothing. The ten over 25 years are not enough to explain the 1.5 W/m² difference between the variable and its computational equivalent, but it might signal another problem. The cloud radiative effect variables come from a model and not direct measurements. In any case, I notified the CERES team of the problem, we’ll see what they find out. This sort of problem is how science advances.

Discussion

The albedo peak from 2004-2007 is very apparent in the CERES EBAF surface radiation data. In the period studied, 2001-2025, it contains the maximum albedo and the maximum surface reflected SW. This is also the period with the minimum SW absorbed by the surface, both under clear skies and all sky conditions. This would normally suggest more snow and ice than normal, but we do not observe a sea-ice anomaly in that period.

Oddly, it is also the time when all sky longwave radiation up from the surface was maximal, both under clear and all skies. Downward SW is low during this period but corresponds to low input from the Sun and it is a time when solar output is declining. Longwave flux down to the surface is high, but not unusually so.

The calculation discrepancies observed appear to be in the CRE variables alone and probably do not affect the other variables, at least as far as I can tell. The cloud effect (CRE) variables do not show an anomaly during this period, but do show one afterward, around 2008-2012 or so. I do not understand these discrepancies; they could be real or computational problems but wanted to document them. This essay is just a brief look at the more interesting things I noticed going through all the CERES EBAF data.

If you are interested in more of the details I uncovered in my study, you can download my PowerPoint slide notes on the 41 CERES EBAF variables here.

Works Cited

Loeb, N. G., Doelling, D., Wang, H., Su, W., Nguyen, C., Corbett, J., & Liang, L. (2018). Clouds and the Earth’s Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) Top-of-Atmosphere (TOA) Edition-4.0 Data Product. Journal of Climate, 31(2). Retrieved from https://journals.ametsoc.org/view/journals/clim/31/2/jcli-d-17-0208.1.xml

Loeb, N. G., Johnson, G. C., Thorsen, T. J., Lyman, J. M., Rose, F. G., & Kato, S. (2021). Satellite and Ocean Data Reveal Marked Increase in Earth’s Heating Rate. Geophysical Research Letters, 48(13). https://doi.org/10.1029/2021GL093047

Loeb, N. G., Wielicki, B. A., Doelling, D. R., Smith, G. L., Keyes, D. F., Kato, S., . . . T. Wong, 2. (2009). Toward Optimal Closure of the Earth’s Top-of-Atmosphere Radiation Budget. J. Climate, 22, 748-766. https://doi.org/10.1175/2008JCLI2637.1

Sorry, Health ‘Experts’ and The Guardian, Climate Change Isn’t Causing a ‘Public Health Emergency’

The Guardian published an article promoting a call by some scientists for the World Health Organization (WHO) to “Declare climate crisis a global public health emergency.” The fact is there is no climate induced public health emergency meriting such action by the WHO. Deaths due to climate factors and temperatures have declined markedly during the period of recent modest warming.

From ClimateRealism

By H. Sterling Burnett

The Guardian published an article promoting a call by some scientists for the World Health Organization (WHO) to “Declare climate crisis a global public health emergency.” The fact is there is no climate induced public health emergency meriting such action by the WHO. Deaths due to climate factors and temperatures have declined markedly during the period of recent modest warming. Deaths from vector-borne diseases are a mixed bag, with some declining and others increasing, but its unclear whether climate change has played a role in any increase. By contrast, a better response to insect-borne diseases is direct action, using technologies to either destroy the insects carrying the diseases or to prevent people from being infected, and expanding the use of medicines developed to minimize the symptoms of and harms caused by the diseases, rather than trying to prevent the spread indirectly by reducing fossil fuel use.

Describing the call for WHO action, The Guardian writes:

The climate crisis should be declared a global public health emergency by the World Health Organization, or millions more people will die unnecessarily, leading international experts have said.

The independent pan-European commission on climate and health (ECCH), which was convened by the WHO, concluded the climate crisis was such a worldwide threat to health that the WHO should declare it “a public health emergency of international concern”

Commission says alert would trigger coordinated international response that could help avoid millions dying.

With the hits to the WHO’s reputation in the aftermath of the COVID-19 debacle, where the WHO denied the virus’ Chinese origins under pressure from the Chinese Communist party, it’s not clear how seriously the world would respond to a call from the WHO to treat climate change as a health emergency. Especially since: a) the United States, its biggest contributor, pulled out of the WHO as a result of its COVID-19 era actions as well as other attempts to enter into the public policy field, like treating gun violence as a public health threat and calling for firearms restrictions; and b) most surveys show a majority of people don’t believe climate change will affect them, and an even larger majority say they are unwilling to pay much at all to fight climate change.

The WHO would be following the science if it refused to accede to The Guardians’ and the ECCH’s call to declare climate change a public health emergency. It is not. Dispositive data clearly show both temperature-related deaths and deaths due to extreme weather events have declined dramatically over the past century, even as the global average temperature — a made up metric based on limited cherry-picked data with no meaningful reference — has slightly risen. (See the graph below detailing the decline in weather related deaths).

That leaves only the claim that climate change is causing an increase in vector-borne diseases, which is very much open to debate. As detailed in Chapter Four of Climate Change Reconsidered II: Fossil Fuels, the vast body of scientific literature refutes climate activists’ claim that climate change is likely to exacerbate the spread of mosquito-borne diseases. Sufficiently high temperatures are a necessary but not a sufficient factor for disease carrying mosquitoes to flourish. Climate Realism has refuted previous claims that climate change was likely to see an upsurge in vector-borne diseases on dozens of occasions, explaining why that is unlikely to be the case, here, here, and here, for example

Malaria, by far the most widespread and prevalent vector-borne disease, the one that also claims the most lives annually, has declined dramatically during the period of modern warming due to direct interventions, primarily the use of pesticides to kill the host mosquitos and medicines to prevent infection. The global death toll for malaria has been cut in half since 2000. It has also not spread to new regions where it had not been previously known historically despite slightly warmer temperatures.

For other insect-borne diseases the trends are a mixed bag, waxing and waning annually except for Dengue fever which has seen a dramatic rise in reported cases. The question is, is this due to solely or primarily to climate change or other factors, and the evidence suggests, that climate change, at best, is playing a small role. Dengue is endemic to countries astride or near the equator, where temperatures have always been and remain suitable for the mosquito species that carries the disease to thrive. While temperatures have increased in the northern latitudes, they have not changed much along the equator, thus a dramatic temperature increase is not making habitat where the carrier mosquitos already thrive more suitable for them. Nor have rainfall patterns changed that much in tropical countries along the equator except where deforestation has altered humidity and cloud formation.

Part of the increase is due to improved reporting and tracking. Many of the host countries haven’t had, and in some cases still have inadequate, strong detection and reporting mechanisms. As a result, Dengue fever cases have likely historically been undercounted, with improved surveillance and reporting now counting cases that would have been missed previously.

In addition, population growth, especially in urban areas, has contributed to the expansion of Dengue. Dense, poorly planned cities create ideal mosquito habitat, such as standing water, crowding, and high human density makes the spread easier – more people living close together as food sources for the mosquitos. Dengue can also spread from mother to child during pregnancy, and through poor blood screening, both problems in developing countries with limited public health screening and high population growth. Finally, Dengue fever has been diagnosed in countries thousands of miles from where it is endemic. This is due to increased mobility, trade, and travel, with tourists being infected during travel and bringing the disease back home and companies bringing the mosquitoes in on goods, like plants, imported into the country. In short, a slight increase in temperatures may speed up the breeding cycle of mosquitoes that carry Dengue fever, but the change is not large enough to account for most of the expansion of the disease.

The quickest, surest way to dramatically reduce the incidences of Dengue fever along with a host of other vector-borne diseases regardless of climate change is through direct interventions, not reducing fossil fuel use in the hope of modestly reducing global average temperatures 50 or 100 years from now. Those might include public health campaigns encouraging populations to drain reservoirs or pools of stagnant water and prevent the collection of stagnant water going forward, improved medical testing, and the widespread access to and use of effective pesticides —often fossil fuel based or derived — in countries and regions lacking such access or where global authorities have discouraged their use. Other options could include speeding up the development and deployment of genetically modified mosquitoes which, in test plots, have suppressed or prevented, mosquito reproduction.

If the WHO wanted to have an impact, it could divert funding from non-public health programs, like any having to do with climate change, or firearms, gender transitioning, or other social and political issues, and devote more resources to the development of vaccines to improve the resistance to or even prevent the spread of various vector-borne diseases and/or to effectively treat such diseases once contracted.

In the end, contrary to the ECCH’s claims there is no legitimate reason for the WHO to declare climate change a public health emergency. Deaths related to temperatures, disease, and extreme weather have declined dramatically during the recent period of modest warming. For ECCH and The Guardian to pretend otherwise is just bad science and bad journalism in pursuit of contested pollical ends, specifically the end of fossil fuel use. Were the WHO to follow ECCH’s and The Guardian’s recommendations, it might only serve to further damage its already beleaguered reputation.

NASA’s AWE Unveils First High-Resolution Images of Gravity Waves Driving Space Weather from Earth’s Atmosphere

The mission collected valuable data over thousands of orbits, with initial datasets released earlier (e.g., after 3,000 orbits in 2025). It surpassed expectations and was deactivated to free up the ISS mounting point for the next experiment. The instrument will eventually be deorbited and burn up on re-entry.

NASA’s Atmospheric Waves Experiment (AWE) successfully concluded its data-collection phase after exceeding its planned two-year mission.

The instrument (Advanced Mesospheric Temperature Mapper) observed airglow — a faint glow at the edge of space — to map these invisible gravity waves as they propagate upward through the mesosphere and into the ionosphere-thermosphere region.

This work helps improve space weather forecasting, which is increasingly important for protecting satellites, power grids, and future space missions. Data analysis will continue for years.

Initial Atmospheric Waves Experiment (AWE) Imaging Analyses: Gravity Wave Sources, Temperatures, Pseudomomentum Fluxes, and Horizontal Wavenumber Spectra at the OH Layer is the title of a key scientific paper on the initial findings from NASA’s Atmospheric Waves Experiment (AWE), published in the Journal of Geophysical Research: Atmospheres on April 29, 2026 (open access).

_____________________________________________________________________________________

Initial Atmospheric Waves Experiment (AWE) Imaging Analyses: Gravity Wave Sources, Temperatures, Pseudomomentum Fluxes, and Horizontal Wavenumber Spectra at the OH Layer

This is the first major peer-reviewed science paper from the AWE mission, published open-access in Journal of Geophysical Research: Atmospheres (Vol. 131, Issue 9, April 29, 2026). It presents initial results from the Advanced Mesospheric Temperature Mapper (AMTM) on the ISS, focusing on high-resolution nighttime observations of the OH airglow layer at ~87 km altitude.

Key Scientific Findings:

Gravity Wave Sources and Diversity:

Mountain Waves (MWs): Strong responses over small islands and major orography (e.g., Southern Andes). Horizontal wavelengths (λh) ~10–300 km (or longer). Show complex breaking, instabilities (e.g., Kelvin-Helmholtz), and vortex structures.
Convective Gravity Waves (CGWs): From deep convection over land/ocean and events like Hurricane Helene. Similar λh range (~10–300 km+).
Secondary Gravity Waves (SGWs): Clear evidence of larger-scale waves (λh ~50–500 km) generated by breaking of primary waves. These propagate farther and can have significant impacts higher up.

Temperature and Brightness Imaging:

Dual imaging (OH Q-line brightness vs. derived temperature) reveals different aspects of wave structures. Temperature maps highlight perturbations (T′), while brightness shows emission variations.
Instabilities are vividly captured: wave breaking, overturning, and small-scale turbulence features.

Pseudomomentum Fluxes (PMFs) and Spectral Analysis (the most important result):

AWE enables along-track, cross-track, and 2D wavenumber spectra of temperature perturbations (T′²) and velocity covariances (<uh’ w’>).
Major Conclusion: The largest contributions to vertical pseudomomentum fluxes (ρ <uh’ w’>, key for momentum transport to upper atmosphere) come from smaller-scale GWs with λh ~30–300 km.
This confirms that the waves AWE was designed to resolve (previously under-observed by satellites with coarser resolution) dominate energy/momentum transport and space weather influences. Larger waves (λh >300 km) contribute less to PMFs.

The paper demonstrates that AWE filled a critical observational gap: previous satellites had lower resolution and couldn’t fully resolve the small-scale waves that carry the most momentum to the mesosphere/lower thermosphere (MLT). These waves drive variability in space weather, affect satellite operations, and influence atmospheric circulation.

The ISS orbit allowed repeat views (~4-day cadence) and multi-swath tracking of wave evolution. Data examples include responses over Japan, Tibet, the Andes, New Zealand, and Hurricane Helene.

The paper is highly technical with multiple figures showing raw images, temperature maps, keograms, and spectra. It sets the stage for future AWE data releases and analyses.

Full Open-Access Link: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025JD045796

Published: Journal of Geophysical Research – Atmospheres

DOI: 10.1029/2025jd045796

Provided: NASA

Authors: David C. Fritts, Robert G. Stockwell, Thomas S. Lund, P.-Dominique Pautet, Kaoru Sato, Dai Koshin, Michael J. Taylor, Ludger Scherliess

Abstract

The NASA Atmospheric Waves Experiment (AWE) employs an OH imager that began measurements aboard the International Space Station (ISS) on 22 November 2023.

The motivation for AWE was to quantify gravity wave (GW) responses to diverse sources and their influences extending into the mesosphere and higher altitudes.

AWE measures temperatures at 2-km cross-track resolution in a 600-km wide imaging swath at ∼87 km during nighttime.

AWE swaths reveal a remarkable range of nighttime GW and instability responses from small to very large spatial scales over diverse terrain, deep convection, and oceans where no sources are apparent.

Mountain wave responses over small islands and large-scale orography exhibit horizontal wavelengths of λ_h ∼ 10–300 km or longer.

Convective GWs likewise reveal λ_h ∼ 10–300 km or larger over land and ocean sources.

AWE also provides clear evidence of secondary GWs having λ_h ∼ 50–500 km in response to strong MW sources.

Additionally, the ISS orbit enables repeat observations over all sites at an ∼4-day cadence and 2–3 successive swaths at an ∼1.5 hr cadence over all sites near the ISS orbit inclination of 51.6°.

AWE swaths enable assessments of along-track, cross-track, and 2-dimensional wavenumber spectra of GW temperatures, T′², and velocity covariances, <u_h‘w′>, for u_h′ = (u′,v′) spanning GW horizontal wavelengths, λ_h ∼ 30–1,000 km or longer.

These spectral evaluations reveal the major contributions to GW pseudomomentum fluxes, ρ<u_h‘w′>, to occur at GW λ_h ∼ 30–300 km.

NASA’s AWE Completes Mission to Study Earth’s Effect on Space Weather

On May 21, ground controllers powered down NASA’s AWE (Atmospheric Waves Experiment) instrument, bringing the data collection phase of the mission to a successful and scheduled end, surpassing its planned two-year mission.

From NASA Science

By Vanessa Thomas

Installed on the exterior of the International Space Station since November 2023, AWE studied atmospheric gravity waves, which are giant ripples in the atmosphere caused by strong winds flowing over tall mountains or by violent weather events, such as tornadoes, thunderstorms, and hurricanes. The AWE instrument looked for these waves in colorful bands of light in Earth’s atmosphere, called airglow. Funded by NASA’s Heliophysics Division, AWE investigated how atmospheric gravity waves propagate upward to space and contribute to space weather — conditions in space that can disrupt satellites, as well as navigation and communications signals.

“The AWE mission has proven that our atmosphere is not a ceiling, but a living, breathing ocean in the sky,” said Joe Westlake, director of NASA’s Heliophysics Division at NASA Headquarters in Washington. “For the first time, we can see how a thunderstorm in the Midwest, a hurricane over Florida, or a wind gust over the Andes sends invisible ripples — atmospheric gravity waves — crashing into the edge of space like waves hitting a shoreline. By mapping these ripples from the International Space Station, we’ve discovered that Earth’s weather doesn’t just end at the clouds, instead it reaches out beyond our planet, shaping the space weather that impacts our orbital economy.”

This artist’s conception depicts the Atmospheric Waves Experiment (AWE) scanning the atmosphere from aboard the International Space Station, measuring variations in infrared airglow to track atmospheric gravity waves as they move up from the lower atmosphere into space.
Utah State University Space Dynamics Laboratory

During AWE’s 30-month residency on the station, the instrument captured four infrared images every second, tallying more than 80 million nighttime images, which is when airglow can be seen. It observed atmospheric gravity waves from numerous extreme weather events, including a tornado outbreak across the central U.S. in May 2024 and Hurricane Helene impacting the gulf coast of Florida in September 2024.

“We’ve seen atmospheric wave signatures associated with major terrestrial events, which provided a clear example of how intense weather systems can generate measurable upper-atmospheric responses,” said AWE’s principal investigator, Ludger Scherliess of Utah State University in Logan.

These events revealed variations in the types of atmospheric gravity waves created by different kinds of storms. For example, when AWE viewed atmospheric gravity waves generated by a thunderstorm in north Texas on May 26, 2024, it saw they were smaller and more irregular, with a notable asymmetry from north to south, compared to waves created by storms in the same part of the country earlier that month.

This image from AWE shows concentric atmospheric gravity waves caused by a severe weather event that included a tornado near the U.S.-Mexico border on May 3, 2024. Captured during orbit 2529 of AWE’s stay on the International Space Station, the image shows waves spreading across Texas and Mexico in near-perfect circles, a sight rarely observed with such clarity prior to the AWE mission.
NASA/Utah State University

It is important to understand variations in the density of plasma, which is electrically charged gas, in Earth’s upper atmosphere instigated by atmospheric gravity waves, because these variations can disrupt radio signals traveling between satellites and the ground, and from satellite to satellite, degrading the accuracy and reliability of systems used for navigation, timing, and communications.

In a recent study, AWE measurements also revealed the gravity waves with the greatest influence on the upper atmosphere have small horizontal wavelengths, ranging from 30 to 300 kilometers, which AWE was specifically designed to measure.

With its data-collection phase complete, the AWE instrument was turned off to make way for another science experiment that will take its place on the outside of the space station. Called CLARREO Pathfinder (Calibration Absolute Radiance and Refractivity Observatory Pathfinder), the new instrument will take measurements of sunlight reflected by Earth and the Moon that are five to 10 times more accurate than those from existing sensors. The exchange of instruments is a key part of the space station’s mission and versatility as an orbiting laboratory for various types of research.

As the International Space Station traveled over the southeastern United States on Sept. 26, 2024, AWE observed atmospheric gravity waves generated by Hurricane Helene as the storm slammed into the gulf coast of Florida. The curved bands extending to the northwest of Florida, artificially colored red, yellow, and blue, show changes in brightness (or radiance) in a wavelength of infrared light produced by airglow in Earth’s mesosphere. The small black circles on the continent mark the locations of cities.

Utah State University

In the coming days, a robotic arm on the space station, called Canadarm2, will remove the AWE instrument from its location. Soon afterward, the AWE instrument will be loaded into part of a SpaceX Dragon cargo spacecraft that will deorbit and burn up as it re-enters the atmosphere. However, all of AWE’s observations will ultimately become available to the public and the scientific community for ongoing research and discovery.

“Data from AWE will continue to be made public for both professional researchers and citizen scientists,” Scherliess said.

Some of this data already is available, including interactive, online visualizations on Utah State University’s website, where AWE’s observations are “painted” in swaths onto a globe or on a map as the space station orbits the planet. Users can rotate the visualizations to view atmospheric gravity waves from different angles.

A still image from an interactive visualization shows AWE data collected over the Western Hemisphere.
Utah State University

Launched on Nov. 9, 2023, AWE is managed by the Explorers Program Office at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Utah State University’s Space Dynamics Laboratory built the AWE instrument and provided the mission operations center.

Hear more about AWE by listening to episode 334 of NASA’s Houston We Have a Podcast, recorded on Jan. 26, 2024.

By Vanessa Thomas
NASA’s Goddard Space Flight Center, Greenbelt, Md.

Amidst heatwave concerns, Labour considers workplace temperature measures

Labour is considering making it illegal to work when it is too hot as part of the drive for net zero.

From NOT A LOT OF PEOPLE KNOW THAT

By Paul Homewood

h/t Ian Magness

From the Telegraph:

Labour is considering making it illegal to work when it is too hot as part of the drive for net zero.

Emma Reynolds, the Environment Secretary, has said she will “carefully consider” proposals including a maximum working temperature that would force firms to let workers down tools during heatwaves.

The measure, recommended by the influential climate change committee (CCC), would aim to “incentivise” businesses to protect workers by keeping their workplaces cool.

The Health and Safety Executive (HSE), the workplace regulator, is developing plans for extra protection during hot weather, but is expected to stop short of setting a specific legal maximum.

The controversial recommendation for an upper limit is set out in a new report from the CCC advising ministers on the risks posed by climate change in the UK and how best to manage them.

It calls for a raft of measures to protect people against worsening heat, floods and droughts, including the rollout of air conditioning in hospitals, care homes, schools and prisons.

In a list of key proposals to help the UK adapt to more intense heat, the CCC urged the Government to “set maximum temperature regulations for workplaces”.

Full story here.

I’m working on the CCC report, which is the usual load of baloney. As ever it warns about summers being several degrees hotter in the next two decades. The usual fantasy stuff, in other words.

The GMB are suggesting a limit of 25C, which truly is mad. Such a regulation would mean several days a year off work. And what happens when temperatures start to drop back in mid afternoon, or the rain clouds appear?

As for workplaces, a 25C regulation would immediately shut down every steel works in the country!

But going back to the CCC’s fantasy claims:

The CCC report warned that by 2050 summers in the UK were predicted to become “significantly warmer” – with temperatures potentially exceeding 40C regularly in the south of England and even hitting 45C in some cases.

Heatwaves in Britain are also expected to become more frequent and last longer, posing increased risks to health, agriculture and infrastructure.

The CCC makes a big play of a single day when temperatures hit 40C at poor quality, junk weather stations. But no serious outfit makes long term projections based on one day’s weather.

Looking at the underlying position, however, heatwaves are not getting significantly worse. Bear in mind, as well, that cleaner air since the 1980s has undoubtedly increased temperatures on sunny days:

Met Office Hadley Centre Central England Temperature Data Download

About That “Super El Niño”

On Thursday, May 14, the NOAA Climate Prediction Center issued its monthly ENSO Diagnostic Discussion. Within hours, CNN ran a piece under the headline:

A Super El Niño is coming. Here’s how a hotter ocean could change the weather near you.

From Watts Up With That?

By Charles Rotter

On Thursday, May 14, the NOAA Climate Prediction Center issued its monthly ENSO Diagnostic Discussion. Within hours, CNN ran a piece under the headline:

A Super El Niño is coming. Here’s how a hotter ocean could change the weather near you.

The piece opens by telling readers that El Niño is “emerging even faster than expected in the Pacific Ocean and odds are increasing that it could become historically strong, a rare ‘Super’ El Niño, by fall or winter.”

That framing is worth examining, because it does not appear in the NOAA discussion the article is built on.

What the forecast actually says

The May 8 ENSO Diagnostic Discussion is direct about current conditions:

ENSO-neutral conditions are present. Equatorial sea surface temperatures (SSTs) are near-to-above-average across the central and eastern Pacific Ocean. El Niño is likely to emerge soon (82% chance in May-July 2026) and continue through Northern Hemisphere winter 2026-27 (96% chance in December 2026 – February 2027).

The El Niño Watch is real. The probability of an El Niño appearing this summer is high. The probability of one persisting into winter is very high. None of that is in dispute.

What gets less attention is what comes next. The CPC’s probabilistic strength forecast assigns roughly a 2-in-3 chance that the November–January 2026-27 peak will be classified as “strong or very strong.” It assigns roughly a 1-in-3 chance that the event peaks as a Super El Niño, defined as a Niño-3.4 relative SST anomaly exceeding 2.0°C.

A 1-in-3 chance, as a matter of statistics, is what one would more commonly describe as “unlikely.” Coin-flip outcomes do not normally get headlines reading “Heads is coming.” The increment from last month’s 1-in-4 probability, a single CPC update earlier, has nonetheless been packaged as a developing trend toward something “historically strong.”

The forecaster running the desk is more measured. Michelle L’Heureux, who leads El Niño and La Niña forecasting at the Climate Prediction Center, told ABC News:

There is substantial uncertainty in the ultimate strength of El Niño. While there is a 2-in-3 chance of a strong or very strong El Niño for the November-January 2026-27 season, there is still a 1-in-3 chance of an event weaker than that.

The CPC’s own update is similarly careful:

Stronger El Niño events do not ensure strong impacts; they can only make certain impacts more likely.

The conditions that have to line up

For a Super El Niño to develop, two systems have to remain in phase. The tropical Pacific upper-ocean heat content has to stay elevated, and the atmospheric circulation has to respond in a way that reinforces the oceanic anomaly rather than damping it.

The current subsurface signal is favorable. Per the CPC’s evolution status document, “negative subsurface temperature anomalies emerged in mid-July 2025 and persisted through mid-December 2025. From mid-December 2025 through late April 2026, positive anomalies developed and gradually increased.” The upper-ocean heat content anomaly is now above average and the thermocline slope index is below average, both consistent with the early stages of a warm event.

The atmospheric piece is the open question. L’Heureux explained the requirement to ABC News:

El Niño depends on the tropical Pacific ocean and atmosphere interacting in a way that reinforces the event. For example, we need to see weaker than average trade winds along the equatorial Pacific Ocean because that will help keep the ocean surface temperatures above average.

That coupling is what separates the strong events from the merely warm ones. The strongest El Niños in the historical record are characterized by sustained ocean-atmosphere coupling through the summer, and whether that coupling materializes this year is what the spring forecast cannot yet resolve.

The spring predictability barrier

ENSO forecasters have a name for the uncertainty L’Heureux is describing. It is called the spring predictability barrier, and it refers to the well-documented tendency for ENSO forecasts issued in boreal spring to perform worse than forecasts issued at other times of year. The tropical Pacific in late spring and early summer sits at a transition point where the coupled ocean-atmosphere system is most sensitive to initial conditions, and forecast skill collapses accordingly.

This is not a quibble from skeptics. The World Meteorological Organization, in its most recent Global Seasonal Climate Update, states the issue plainly:

Models indicate that this may be a strong event, but the so-called spring predictability barrier is a challenge for the certainty of forecasts at this time of year.

The WMO is even more cautious about the upper bound:

While some model forecasts indicate the possibility of stronger conditions later in the year, there is currently no consensus or sufficient confidence to confirm or exclude a high-intensity event.

That is the operating expert community describing a forecast that the press is presenting as a near-certainty.

The buried admission

Among the more striking numbers in the current forecast cycle is one that has not received much coverage. The same NOAA office that issued the El Niño Watch, NOAA’s National Centers for Environmental Information, has also issued its outlook for 2026 global temperature rankings.

According to that outlook, there is a 96% probability that 2026 ranks among the five warmest years in the instrumental record.

There is a less than 1% probability that 2026 sets a new record.

That admission deserves a moment. After three years in which “warmest year on record” headlines have followed every January with metronomic regularity, the agency that produces those rankings has now publicly assessed that even with a developing El Niño, even with a 2-in-3 chance of a strong or very strong event, 2026 has effectively no chance of beating the recent peak.

The implication is straightforward. The 2023–2024 spike, the one attributed at the time to everything from anthropogenic forcing to the Hunga Tonga eruption to the IMO 2020 reduction in marine sulfate emissions, has subsided. NCEI now puts the probability of clearing it this year at less than 1%, and the probability of clearing it next year depends entirely on whether the developing El Niño manages to peak in the upper portion of its forecast distribution.

This is the kind of quiet methodological update that ought to inform public framing of climate trends. Instead, it sits under a 96% top-five-warmest headline that obscures the more interesting structural detail.

The 2015-16 precedent

Comparison to the last Super El Niño is worth doing carefully. The 2015–16 event was, in NOAA’s records dating to 1950, the strongest El Niño ever observed. It cleared the 2.0°C Niño-3.4 threshold and remained there for an extended period. By every standard objective metric it was, in fact, super.

The CNN article concedes that even a super event’s predicted impacts do not necessarily materialize:

The 2015-2016 Super El Niño delivered on its reputation of causing serious drought in the Caribbean, but also failed to produce the wetter than average winter it’s known for in Southern California.

Southern California’s expected El Niño response, wetter winters, replenished reservoirs, drought relief, is the canonical impact in the popular imagination. The 2015–16 event was the largest El Niño on record. It failed to produce that response.

The CPC’s standard caveat, that strong events make certain impacts “more likely” but do not ensure them, is doing a lot of work here. In the most extreme observed case, in the region with the most widely publicized expected impact, the relationship did not hold. That is the kind of empirical result that should temper confident projections about what a possibly-Super-and-probably-not El Niño will do to weather patterns nine to twelve months out.

One technical change is worth flagging because it affects how this event will be compared to its predecessors. In February 2026, NOAA moved to a relative ONI methodology, in which the Niño-3.4 SST anomaly is computed as the departure from the tropical-mean SST rather than from a fixed climatological base period. The relative index is then rescaled to match the variance of the traditional index.

The motivation is reasonable: with the entire tropics warming, the older absolute-anomaly approach was producing El Niño classifications during periods when the equatorial Pacific was not, in fact, anomalously warm relative to the surrounding ocean. The relative index isolates the actual ENSO signal more cleanly.

The practical effect is that direct comparisons between the 2015–16 event under the old methodology and a possible 2026–27 event under the new methodology require some care. A “Super” classification today is not measuring exactly the same quantity it measured a decade ago. This is a defensible scientific update, but it is worth noting whenever the “strongest on record” framing is invoked.

None of this is to suggest that there is no El Niño developing, or that NOAA’s forecasters are wrong about the probabilities they are publishing. The CPC’s discussions are careful, the probability ranges are reasonable, and the model agreement on emergence by mid-year is broad and consistent.

The issue is the translation layer.

The forecast says: 82% chance of El Niño emerging by July, 96% chance of persistence into winter, 2-in-3 chance of peaking strong or very strong, 1-in-3 chance of clearing the Super threshold, substantial uncertainty in ultimate strength, spring predictability barrier limiting confidence, no expert consensus on high-intensity scenarios, and a less than 1% chance that 2026 sets a new annual temperature record.

The coverage says: “A Super El Niño is coming.”

These are not the same statement. One is a probability distribution with explicit uncertainty bounds drawn by the forecaster running the desk. The other is a declarative claim about a specific outcome at the upper tail of that distribution.

The CPC has done the responsible thing by publishing the underlying probabilities, by quoting its own scientist’s uncertainty caveats, and by including the standard reminder that impacts do not follow mechanically from category. The next ENSO Diagnostic Discussion is scheduled for June 11. By then the spring predictability barrier will have started to dissolve, and the probability ranges will tighten. Whether they tighten upward toward a Super event or downward toward a routine moderate one is, at this point, genuinely unknown.

In the meantime, “could become historically strong” is what the forecast actually allows. “Is coming” is what the headline says.

Day: May 22, 2026

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