More than just CO2 - an Antropogenic Climate Sensitivity

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Tom Harris

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May 20, 2026, 6:52:29 AM (20 hours ago) May 20
to Healthy Planet Action Coalition (HPAC)
Hi,
I've been mulling over how its not just CO2 and other GHGs that drive ECS and put it down on digital paper in an article just published on my Substack.
Pretty nerdy stuff, but with significant implications for CDR, especially in relation to the new CMIP7 scenarios and managing overshoot. 
Very relevant for cooling methods too I think.
Best,
Tom

Tom Goreau

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May 20, 2026, 7:12:57 AM (20 hours ago) May 20
to Tom Harris, Healthy Planet Action Coalition (HPAC)

Thanks so much for this, Tom!

 

ALL important feedbacks (many of which have very long time lags, especially the geophysical ones) must be included in any useful estimate of ECS, but I would not expect all of Earth history to fit on a single smooth line like this beautiful interpolation, as there will be significant fluctuations (“noise”) caused by plate tectonic controlled factors that affect ocean circulation, volcanism, weathering, rainfall patterns, etc. that could last tens of millions of years.

 

Best wishes,

Tom

 

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Dan Miller

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May 20, 2026, 1:24:35 PM (13 hours ago) May 20
to Tom Goreau, Tom Harris, Healthy Planet Action Coalition (HPAC)
Hi Tom:

Great graphic!

We now know that the cloud feedback is quite positive. See:

Global WarmingFewer CloudsMore Warming! with George Tselioudis

https://youtube.com/live/suFZb2ViHoA


Best,

Dan

robert...@gmail.com

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May 20, 2026, 4:43:38 PM (10 hours ago) May 20
to healthy-planet-...@googlegroups.com

I've been experimenting with the impact of different values of ECS on climate projections in my WTF/FaIR model.

These are simulations from just one model but they suggests that the impact of high values of ECS emerges quite slowly over periods much longer than current policy relevant periods.  Avoiding major short-term grief requires policies that are are hardly touched by whatever the 'correct' value of ECS is.

We're struggling to get onto the first rung of the climate policy ladder marked ECS=3o so replacing it with an even higher and steeper one marked ECS=4.5oC will make little, if any, practical difference.

If people aren't that moved by the likely plight of their grandchildren (which ECS=3o portends with high confidence), why would they be more moved by the even worse plight of their great grandchildren?

We either have to find a way to make people care sufficiently about their grandchildren's future to bite the climate bullet now, or accept that until the wheels really start falling off the global economy bus, no one is going to be moved to do the maintenance to ensure the wheels keep the bus on the road.  Of course, the latter course of (in)action greatly increases the likelihood that by then, the spare parts will no longer be available!

Regards

RobertC


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