May 26, 2026 NYT article links this post by Roger:
"The new emissions scenarios, published last month, are an attempt to create better inputs for the next generation of climate models. The authors said they discarded the RCP8.5 scenario because it had “become implausible” thanks to actions countries have taken to tackle climate change. (Some experts dispute that rationale, saying that RCP8.5 was never plausible.)"
This is great information. I am using it today to help scope a watershed plan update that was using SSP5-8.5 as the 'default' future climate scenario. The watershed managers have not been following the shift to plausible scenarios :)
So what’s the next step? What should happen to the thousands of papers published based on RCP 8.5? What should happen to all the policies based on RCP 8.5? Should the EPA purge its records of all research based on RCP 8.5?
I have lost so much faith in scientists and their institutions over RCP8.5 and its consequences. I feel quite sad about it. Very well done for standing up for truth.
What I wonder is, if the CMIP community needed a high net radiative forcing pathway to drive GCM (General Circulation Models)-generated projections, why bother trying to create one via such a contrived process? Why not simply prescribe a pathway that winds up with +8.5 w/m^2 by 2100? And also why not simply prescribe a lower-RF pathway resulting in ~2C warming, given the also well-known plausibility problems with RCP-2.6/SSP1-2.6? This would have satisfied the earth-system modelling community's need for strongly-contrasting simulation targets without requiring socio-techno-economic assumptions of fragile plausibility.
IPCC had already started to distance itself from SSP5-8.5/RCP8.5 by the time the AR6 WGIII report was finalized. A few quotes from the AR6 WGIII report: "High-end emission scenarios, such as RCP8.5 and SSP5-8.5, are becoming less likely with climate policy and technology change (Box 3.3), but high-end concentration and warming levels may still be reached with the inclusion of strong carbon or climate feedbacks". "... since 2011, the rapid development of renewable energy technologies and emerging climate policy have made it considerably less likely that emissions could end up as high as RCP8.5." [Citing Hausfather & Peters 2020 paper]. "It is important to realise that RCP8.5 and SSP5-8.5 do not represent a typical ‘business-as-usual’ projection but are only useful as high-end, high-risk scenarios."
Roger, I'm impressed with your sticking to the facts regarding climate change. This 20 May 2026 article in Reason, "How Tom Steyer Used His Money To Fuel Climate Hysteria" documents how you were targeted by the Obama administration and the University of Colorado. https://reason.com/2026/05/20/how-tom-steyer-used-his-money-to-fuel-climate-hysteria/
This article contains the text of John Stossel's 19 May 2026 13:33 compelling Stossel TV video, "Buffaloed: How a Climate Scientist Was Attacked by the White House, Congress & His Own University" https://www.youtube.com/watch?v=9fyFbPWpZzs
I'm grateful that you persisted and are now associated with the American Enterprise Institute. You are an inspiration for my pro-nuclear power advocacy as a scientist at https://greennuke.substack.com/
Using that vague Hausfather quote to back up your point given Zeke's generally held position on RCP8.5 over the years is a strech that doesn't look good at all.
Yes, he labels it as a intended "worst case scenario" and no, it wasn't really that either but that's minor detail in the bigger picture.
Goodness. And anyway wind and solar are not cheap. The equipment from China certainly is, especially with dumping. The bill to use this stuff is pretty expensive. Amazing how disingenuous people can be.
A serious question is whether sensitivity to trace gases is plausible as modelled. That will be the next sacred cow to get tossed.
This is to ask again about the Hansen assertion that climate sensitive is definitely at least 4.5. Years ago, when establishing the various scenarios, was any attempt made to say that higher numbered scenarios could be equated to later agreement that the value 3 was too low? Secondarily, asking my AI helper how methane fits in, the answer: combined sensitivity could be as large as 9. In your view, what chance that the new high scenarios could be close to the real future?
According to Gemini, the sheer volume of global energy consumption provided by hydrocarbons was roughly 303 exajoules (EJ) in 1990. By the end of 2024, that number climbed to 513 exajoules. Coal use alone has increased 75% globally, mostly in China and India. How can anyone credit climate policies for reducing climate change risk when total hydrocarbon use climbed 69% over the past 35 years?
I think it insightful and largely consistent with your post. It also gives some historical context while not being particularly divisive. (I’ll be poking around for more info; any suggestions?)
You have stated in various interviews that no one is blameless in this and that nothing particularly nefarious is going on. Though based on comments below, one might think otherwise. The gap in communication and understanding between the science and energy policy communities is certainly problematic and needs to be addressed in an objective fashion going forward. Just my 2¢.
Roger - like you predicted, the NY Times (only an example, I'm sure there will be more) writes that abandoning RCP8.5 was only a 'tweak' and it's all attributed to the growth in renewable energy which made "the worst-case scenario a bit less bad."
Of course the New York Times portrays it this way in today's paper: SCIENTISTS TWEAKED THE GLOBAL WARMING OUTLOOK. SO TRUMP WEIGHS IN. Renewable energy has helped make the worse-case scenario a bit less bad. The president said, falsely, it shows that climate scientists were wrong all along...
In addition to the implausible assumptions described in this post, in an earlier post Roger said the RCP-8.5 model assumed a 2100 global population approaching 13B. (UN now estimates 2100 global population at 10.2B and their forecasts have been decreasing.) Now, think about this: The RCP-8.5 projects a global average temperature increase of as much as 6 deg C over preindustrial times and they claim that an increase of more than 2 deg C will cause famines, crop losses and all kinds of weather disasters. So, how does their population growth forecast jibe with a world that is frying? Logic is inconsistent.
Excellent article, but one statement in the subtitle is difficult to understand: why “getting things right” is supposed to be “uncomfortable”? Most of us are very comfortable with the truth about RCP8.5 . The only ones who should feel very, very uncomfortable are those scientists who either wrote endless “studies” based on this scenario or watched this pseudo-scientific literature accumulate and said and did nothing, although they were told years ago that the scenario is implausible - assuming that their own scientific skills were too weak to figure that out.
Roger’s statement in the subtitle sounds strangely apologetic to the “climate scientist community”. Shouldn’t they be the ones apologizing?
May 26, 2026 NYT article links this post by Roger:
"The new emissions scenarios, published last month, are an attempt to create better inputs for the next generation of climate models. The authors said they discarded the RCP8.5 scenario because it had “become implausible” thanks to actions countries have taken to tackle climate change. (Some experts dispute that rationale, saying that RCP8.5 was never plausible.)"
This is great information. I am using it today to help scope a watershed plan update that was using SSP5-8.5 as the 'default' future climate scenario. The watershed managers have not been following the shift to plausible scenarios :)
Good news !!! I got the study rescoped to drop 8.5 as the default scenario :)
So what’s the next step? What should happen to the thousands of papers published based on RCP 8.5? What should happen to all the policies based on RCP 8.5? Should the EPA purge its records of all research based on RCP 8.5?
Great Q!
To be addressed soon here at THB …
I have lost so much faith in scientists and their institutions over RCP8.5 and its consequences. I feel quite sad about it. Very well done for standing up for truth.
What I wonder is, if the CMIP community needed a high net radiative forcing pathway to drive GCM (General Circulation Models)-generated projections, why bother trying to create one via such a contrived process? Why not simply prescribe a pathway that winds up with +8.5 w/m^2 by 2100? And also why not simply prescribe a lower-RF pathway resulting in ~2C warming, given the also well-known plausibility problems with RCP-2.6/SSP1-2.6? This would have satisfied the earth-system modelling community's need for strongly-contrasting simulation targets without requiring socio-techno-economic assumptions of fragile plausibility.
IPCC had already started to distance itself from SSP5-8.5/RCP8.5 by the time the AR6 WGIII report was finalized. A few quotes from the AR6 WGIII report: "High-end emission scenarios, such as RCP8.5 and SSP5-8.5, are becoming less likely with climate policy and technology change (Box 3.3), but high-end concentration and warming levels may still be reached with the inclusion of strong carbon or climate feedbacks". "... since 2011, the rapid development of renewable energy technologies and emerging climate policy have made it considerably less likely that emissions could end up as high as RCP8.5." [Citing Hausfather & Peters 2020 paper]. "It is important to realise that RCP8.5 and SSP5-8.5 do not represent a typical ‘business-as-usual’ projection but are only useful as high-end, high-risk scenarios."
Roger, I'm impressed with your sticking to the facts regarding climate change. This 20 May 2026 article in Reason, "How Tom Steyer Used His Money To Fuel Climate Hysteria" documents how you were targeted by the Obama administration and the University of Colorado. https://reason.com/2026/05/20/how-tom-steyer-used-his-money-to-fuel-climate-hysteria/
This article contains the text of John Stossel's 19 May 2026 13:33 compelling Stossel TV video, "Buffaloed: How a Climate Scientist Was Attacked by the White House, Congress & His Own University" https://www.youtube.com/watch?v=9fyFbPWpZzs
I'm grateful that you persisted and are now associated with the American Enterprise Institute. You are an inspiration for my pro-nuclear power advocacy as a scientist at https://greennuke.substack.com/
Using that vague Hausfather quote to back up your point given Zeke's generally held position on RCP8.5 over the years is a strech that doesn't look good at all.
Yes, he labels it as a intended "worst case scenario" and no, it wasn't really that either but that's minor detail in the bigger picture.
Goodness. And anyway wind and solar are not cheap. The equipment from China certainly is, especially with dumping. The bill to use this stuff is pretty expensive. Amazing how disingenuous people can be.
A serious question is whether sensitivity to trace gases is plausible as modelled. That will be the next sacred cow to get tossed.
This is to ask again about the Hansen assertion that climate sensitive is definitely at least 4.5. Years ago, when establishing the various scenarios, was any attempt made to say that higher numbered scenarios could be equated to later agreement that the value 3 was too low? Secondarily, asking my AI helper how methane fits in, the answer: combined sensitivity could be as large as 9. In your view, what chance that the new high scenarios could be close to the real future?
According to Gemini, the sheer volume of global energy consumption provided by hydrocarbons was roughly 303 exajoules (EJ) in 1990. By the end of 2024, that number climbed to 513 exajoules. Coal use alone has increased 75% globally, mostly in China and India. How can anyone credit climate policies for reducing climate change risk when total hydrocarbon use climbed 69% over the past 35 years?
I’ve been poking around for some background on the RCP 8.5 issue. Came across this article posted in 2019. https://www.carbonbrief.org/explainer-the-high-emissions-rcp8-5-global-warming-scenario/
I think it insightful and largely consistent with your post. It also gives some historical context while not being particularly divisive. (I’ll be poking around for more info; any suggestions?)
You have stated in various interviews that no one is blameless in this and that nothing particularly nefarious is going on. Though based on comments below, one might think otherwise. The gap in communication and understanding between the science and energy policy communities is certainly problematic and needs to be addressed in an objective fashion going forward. Just my 2¢.
Roger - like you predicted, the NY Times (only an example, I'm sure there will be more) writes that abandoning RCP8.5 was only a 'tweak' and it's all attributed to the growth in renewable energy which made "the worst-case scenario a bit less bad."
https://www.nytimes.com/2026/05/18/climate/trump-global-warming-truth-social.html?emc=edit_th_20260519&nl=today%27s-headlines&segment_id=220061
Yes, AP and NYT try to minimize this. And not well either! I may do a post on all the coverage that resulted from Trumps tweet.
Of course the New York Times portrays it this way in today's paper: SCIENTISTS TWEAKED THE GLOBAL WARMING OUTLOOK. SO TRUMP WEIGHS IN. Renewable energy has helped make the worse-case scenario a bit less bad. The president said, falsely, it shows that climate scientists were wrong all along...
In addition to the implausible assumptions described in this post, in an earlier post Roger said the RCP-8.5 model assumed a 2100 global population approaching 13B. (UN now estimates 2100 global population at 10.2B and their forecasts have been decreasing.) Now, think about this: The RCP-8.5 projects a global average temperature increase of as much as 6 deg C over preindustrial times and they claim that an increase of more than 2 deg C will cause famines, crop losses and all kinds of weather disasters. So, how does their population growth forecast jibe with a world that is frying? Logic is inconsistent.
Excellent article, but one statement in the subtitle is difficult to understand: why “getting things right” is supposed to be “uncomfortable”? Most of us are very comfortable with the truth about RCP8.5 . The only ones who should feel very, very uncomfortable are those scientists who either wrote endless “studies” based on this scenario or watched this pseudo-scientific literature accumulate and said and did nothing, although they were told years ago that the scenario is implausible - assuming that their own scientific skills were too weak to figure that out.
Roger’s statement in the subtitle sounds strangely apologetic to the “climate scientist community”. Shouldn’t they be the ones apologizing?