"Where do climate models go for their apology?"

Climatologist Andrew Dessler on Bluesky:

where do climate models go for their apology

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— Andrew Dessler (@andrewdessler.com) June 11, 2025 at 7:51 PM

Lewis's and Curry's predicted values for TCR (1.33°C) and ECS (1.64°C) are spectacularly wrong. 

TCR = Transient Climate Response = global temperature change at the time when CO2 has doubled.

ECS = Equilibrium Climate Sensitivity = global temperature change when the climate has stabilized after CO2 has doubled, viz. after short-term and long-term feedbacks have played out.

We're at CO2 = 430 parts per million, so CO2 is up 54% since its pre-industrial value of 280 ppm. Nowhere close to doubling. Global warming in their year of 2014 was (GISS) 0.75°C and in 2024 was 1.24°C. 2024 was an exceptional year so let's take the average of the five years up through 2024; that's 1.05°C. +0.29°C in just about 7.5 years. 

At that rate their TCR will be attained in another about 7-10 years. That's a very bad prediction. It was just obviously not at all likely. I'm surprised it passed peer review. It could be wrong by a factor of 2 at the rate temperature has increased since 1975 (1.30 C). That's a bit of a cherry pick since for whatever reasons (clean air regulations on cars? higher emissions?) temperature took off around 1975

 

I think it's hard to grasp how massive a 0.20-0.25°C/decade increase is. It's starting to seem normal in a sense, but it's anything but.