Extreme Temperature Diary- Friday September 26th, 2025/Main Topic: 5 Forecasts Early Climate Models Got Right

5 forecasts early climate models got right – the evidence is all around you

5 forecasts early climate models got right – the evidence is all around you

With the kind permission of the author, Dr. Nadir Jevanjee of the Geophysical Fluid Dynamics Laboratory in Princeton, we are re-posting his article, “5 forecasts early climate models got right”. It was originally posted online in The Conversation on Sept. 3, 2025. The article nicely summarizes some of the key forecasts made by early climate models. These forecasts were subsequently confirmed by the observations of many different research teams. The success of these early forecasts – some of which were made over 60 years ago – underscores our predictive understanding of important aspects of the physics and mechanisms driving the climate system’s response to human-caused increases in greenhouse gases.

Climate models are complex, just like the world they mirror. They simultaneously simulate the interacting, chaotic flow of Earth’s atmosphere and oceans, and they run on the world’s largest supercomputers.

Critiques of climate science, such as the report written for the Department of Energy by a panel in 2025, often point to this complexity to argue that these models are too uncertain to help us understand present-day warming or tell us anything useful about the future.

But the history of climate science tells a different story.

The earliest climate models made specific forecasts about global warming decades before those forecasts could be proved or disproved. And when the observations came in, the models were right. The forecasts weren’t just predictions of global average warming – they also predicted geographical patterns of warming that we see today.

Syukuro Manabe was awarded the Nobel Prize in physics in 2021. Johan Nilsson/TT News Agency/AFP

These early predictions starting in the 1960s emanated largely out of a single, somewhat obscure government laboratory outside Princeton, New Jersey: the Geophysical Fluid Dynamics Laboratory. And many of the discoveries bear the fingerprints of one particularly prescient and persistent climate modeler, Syukuro Manabe, who was awarded the 2021 Nobel Prize in physics for his work.

Manabe’s models, based in the physics of the atmosphere and ocean, forecast the world we now see while also drawing a blueprint for today’s climate models and their ability to simulate our large-scale climate. While models have limitations, it is this track record of success that gives us confidence in interpreting the changes we’re seeing now, as well as predicting changes to come.

Forecast No. 1: Global warming from CO2

Manabe’s first assignment in the 1960s at the U.S. Weather Bureau, in a lab that would become the Geophysical Fluid Dynamics Laboratory, was to accurately model the greenhouse effect – to show how greenhouse gases trap radiant heat in Earth’s atmosphere. Since the oceans would freeze over without the greenhouse effect, this was a key first step in building any kind of credible climate model.

To test his calculations, Manabe created a very simple climate model. It represented the global atmosphere as a single column of air and included key components of climate, such as incoming sunlight, convection from thunderstorms, and his greenhouse effect model.

Results from Manabe’s 1967 single-column global warming simulations show that as carbon dioxide (CO2) increases, the surface and lower atmosphere warm, while the stratosphere cools. Syukuro Manabe and Richard Wetherald, 1967

Despite its simplicity, the model reproduced Earth’s overall climate quite well. Moreover, it showed that doubling carbon dioxide concentrations in the atmosphere would cause the planet to warm by about 5.4 degrees Fahrenheit (3 degrees Celsius).

This estimate of Earth’s climate sensitivity, published in 1967, has remained essentially unchanged in the many decades since and captures the overall magnitude of observed global warming. Right now the world is about halfway to doubling atmospheric carbon dioxide, and the global temperature has warmed by about 2.2 F (1.2 C) – right in the ballpark of what Manabe predicted.

Other greenhouses gases such as methane, as well as the ocean’s delayed response to global warming, also affect temperature rise, but the overall conclusion is unchanged: Manabe got Earth’s climate sensitivity about right.

Forecast No. 2: Stratospheric cooling

The surface and lower atmosphere in Manabe’s single-column model warmed as carbon dioxide concentrations rose, but in what was a surprise at the time, the model’s stratosphere actually cooled.

Temperatures in this upper region of the atmosphere, between roughly 7.5 and 31 miles (12 and 50 km) in altitude, are governed by a delicate balance between the absorption of ultraviolet sunlight by ozone and release of radiant heat by carbon dioxide. Increase the carbon dioxide, and the atmosphere traps more radiant heat near the surface but actually releases more radiant heat from the stratosphere, causing it to cool.

This cooling of the stratosphere has been detected over decades of satellite measurements and is a distinctive fingerprint of carbon dioxide-driven warming, as warming from other causes such as changes in sunlight or El Niño cycles do not yield stratospheric cooling.

Forecast No. 3: Arctic amplification

Manabe used his single-column model as the basis for a prototype quasi-global model, which simulated only a fraction of the globe. It also simulated only the upper 100 meters or so of the ocean and neglected the effects of ocean currents.

In 1975, Manabe published global warming simulations with this quasi-global model and again found stratospheric cooling. But he also made a new discovery – that the Arctic warms significantly more than the rest of the globe, by a factor of two to three times.

This “Arctic amplification” turns out to be a robust feature of global warming, occurring in present-day observations and subsequent simulations. A warming Arctic furthermore means a decline in Arctic sea ice, which has become one of the most visible and dramatic indicators of a changing climate.

Forecast No. 4: Land-ocean contrast

In the early 1970s, Manabe was also working to couple his atmospheric model to a first-of-its-kind dynamical model of the full world ocean built by oceanographer Kirk Bryan.

Around 1990, Manabe and Bryan used this coupled atmosphere-ocean model to simulate global warming over realistic continental geography, including the effects of the full ocean circulation. This led to a slew of insights, including the observation that land generally warms more than ocean, by a factor of about 1.5.

How global ocean and land temperatures have risen

Annual land and sea surface temperature anomalies each year compared to the 20th century average show ocean temperatures respond more slowly but are also rising.

Lines showing temperature differences from the 20th century average by year. The land temperatures rise faster but both are going up. La Nina’s masking of ocean heat is evident in periods where temperatures appear to level off for a couple of years.

As with Arctic amplification, this land-ocean contrast can be seen in observed warming. It can also be explained from basic scientific principles and is roughly analogous to the way a dry surface, such as pavement, warms more than a moist surface, such as soil, on a hot, sunny day.

The contrast has consequences for land-dwellers like ourselves, as every degree of global warming will be amplified over land.

Forecast No. 5: Delayed Southern Ocean warming

Perhaps the biggest surprise from Manabe’s models came from a region most of us rarely think about: the Southern Ocean.

This vast, remote body of water encircles Antarctica and has strong eastward winds whipping across it unimpeded, due to the absence of land masses in the southern midlatitudes. These winds continually draw up deep ocean waters to the surface.

Winds around Antarctica contribute to upwelling of cold deep water that keeps the Southern Ocean cool while also raising nutrients to the surface waters. NOAA

Manabe and colleagues found that the Southern Ocean warmed very slowly when atmospheric carbon dioxide concentrations increased because the surface waters were continually being replenished by these upwelling abyssal waters, which hadn’t yet warmed.

This delayed Southern Ocean warming is also visible in the temperature observations.

What does all this add up to?

Looking back on Manabe’s work more than half a century later, it’s clear that even early climate models captured the broad strokes of global warming.

Manabe’s models simulated these patterns decades before they were observed: Arctic Amplification was simulated in 1975 but only observed with confidence in 2009, while stratospheric cooling was simulated in 1967 but definitively observed only recently.

Climate models have their limitations, of course. For instance, they cannot predict regional climate change as well as people would like. But the fact that climate science, like any field, has significant unknowns should not blind us to what we do know.

Exceptionally low max temperatures in France yesterday🌡10.9°C Paris ➡️ 4th lowest September max since 1873!🌡9.1°C Limoges ➡️ 2nd lowest since 1973!🌡10.5°C Metz ➡️ 2nd lowest since 1936 [no data 1951-1972]!🌡11.1°C Orly ➡️ 2nd lowest since 1949!And many more.

Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-09-25T20:13:59.188Z

EXCEPTIONAL HEAT IN THE SAHARAWhile Europe is shivering,North Africa is baking in the unprecedented late September heat waveINCREDIBILE Minimum 32.9C at Bordji B. Mokhtar,ALGERIA, unprecedented in Africa this time of the yearMax temperatures near 45C,also at record levels

Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-09-26T15:34:22.544Z

Southeast Asia record heat continues with minimums up to 29C again in Thailand and records broken every day in INDONESIA.Tonight the Minimum at Palangkaraya was 25.8C, highest minimum recorded in September.From early 2023,records have been falling every day without exceptions

Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-09-26T02:20:07.356Z

Endless summer in JAPANToday new September record at Tokashiki with 31.7C.Widespread temperatures 30C/35C with stifling hot nights (mins up to 27C) will continue in October:Let's expect hundreds of records in the coming weeks.Summer will go on…

Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-09-26T10:09:32.180Z

Record heat is everywhere, every day.Unprecedented hot nights for this time of the year also inBANGLADESHBoth Bogra and Tarash had a Minimum temperature of29.0C, their hottest September night in history.

Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-09-26T11:46:08.750Z

EXCEPTIONAL HEAT IN THE CARIBBEANRelentless heat with stifling hot nights and Minimums >29C in Mexico,Bo.naire,Cayman Islands,Grenada etcIn Particular the Minimum of 29.8C at Owen Int. AP is GRAN CAYMAN HOTTEST NIGHT IN HISTORYAll tropics are smashing record after record

Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-09-25T21:40:31.316Z

🌡️HISTORIC HOT NIGHTMinimum temperature today of 88.6F/31.4C in the Badwater Basin,Death Valley 🇺🇸:It's exceptional and at Record hot level for all Americas for this time of the year.

Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-09-25T18:45:09.893Z

80% – 89% of the world’s population wants to see #climate action. www.theguardian.com/environment/…

Dr Paul Dorfman (@drpauldorfman.bsky.social) 2025-09-26T07:03:46.538Z

Here's a gift link opening up access to everybody. (Some fraction seem to be prompted to regisiter)www.sfchronicle.com/opinion/open…

David Sacerdote (@davidsacerdote.bsky.social) 2025-09-26T15:00:46.763Z

The oceans just hit an ominous milestoneA new report sounds the alarm on ocean acidification as Earth breaches the seventh of nine "planetary boundaries."grist.org/oceans/the-o…#Climate #Oceans #Heat #Seas #Fish #MarineLife #Environment #Water

Grist (@grist.org) 2025-09-26T17:05:10.430Z

This week’s Talking Climate is guest-edited by physicist David Baker from Austin College. David is a NASA exoplanet researcher and professor whose work inspires students and communities to connect the cosmos back to our own remarkable planet.MailChimp: shorturl.at/XnmmgLinkedIn: shorturl.at/lywQ8

Katharine Hayhoe (@katharinehayhoe.com) 2025-09-25T21:57:17.773Z

www.quantamagazine.org/the-climate-…There are thousands of factors that influence our #ClimateThe Climate Paradox is a deep dive into our weather patterns and everything that influences them, past and present 🌎#VoteClimate#BlueEarth#ResistanceEarth#OV1

Amarie (@humanwolf.bsky.social) 2025-09-26T15:28:47.709Z

An exceedingly complex forecast lies ahead for #Humberto and #94L. Of the latter, the Nat'l Hurricane Center warns that "the chances of wind, rainfall, and storm surge impacts for a portion of the southeast U.S. coast are increasing.” Full scoop here:yaleclimateconnections.org/2025/09/gabr…

Bob Henson (@bhensonweather.bsky.social) 2025-09-25T18:18:46.551Z

#Humberto now forecast to become a monster Cat 4 winds 145 mph!If so, it would be the 3rd major storm this season… there have only been 3 hurricanes this season… so 3 for 3 with rapid intensification reaching major status. Amazing. Good news: No threat to landfall.

Jeff Berardelli (@weatherprof.bsky.social) 2025-09-26T15:46:26.444Z

The potential for 2 Hurricanes off the Eastern Seaboard early next week, and one of them, #Imelda may landfall in South or North Carolina, after making a direct hit on the Bahamas. It’s complicated. I break it down here. #humberto #fyp #Hurricane #southcarolina

Jeff Berardelli (@weatherprof.bsky.social) 2025-09-26T01:33:41.542Z

Can two hurricanes on a collision course merge into a Monster, the perfect #hurticane?#Humberto and #Imelda will be 100s of miles from each other. How will they interact? This is the first of an ongoing series of educational weather & #climate videos from me, The Weather Professor. Follow along!

Jeff Berardelli (@weatherprof.bsky.social) 2025-09-26T12:33:13.575Z

Ex-hurricane #Gabrielle is crossing the #Azores early morning Friday… still at Category 1 hurricane intensity.bmcnoldy.earth.miami.edu/tropics/radar/

Brian McNoldy (@bmcnoldy.bsky.social) 2025-09-26T03:27:20.345Z

Used EVs have never been cheaper. But are they a good deal?The price gap between used electric and gas cars is now just $900 — that's the lowest ever.grist.org/economics/us…#EV #Transportation #Climate #Economics #Economy #Cars #UsedCars #Business #Batteries

Grist (@grist.org) 2025-09-25T16:37:32.442Z

What would an Indigenous Law of the Sea look like?From deep-sea mining to climate change, this Indigenous woman sees a better future for the world's oceans.grist.org/global-indig…#Law #Oceans #Climate #Legal #Indigenous #Seas #Mining

Grist (@grist.org) 2025-09-25T16:26:55.968Z

We are searching for a Forest Ecophysiologist (tenure track Assistant or Associate Professor) to join the Department of Forest and Conservation Sciences, University of British Columbia Faculty of Forestry. Please share! Details are here: ubc.wd10.myworkdayjobs.com/ubcfacultyjobs

Sally Aitken 🇨🇦 (@sallyaitken.bsky.social) 2025-09-25T21:28:14.410Z

Great sunset at Yavapai Point, Grand Canyon tonight.

Dr. Jeff Masters (@drjeffmasters.bsky.social) 2025-09-26T02:12:15.617Z

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