James Hansen: Sophie's Planet and Terminations

[OKIsItJustMe]

https://www.columbia.edu/~jeh1/mailings/2024/May30Email.2024.05.30.pdf

Antarctic (Dome C) temperature and Earth orbital parameters (1 kyr = 1000 years).

Sophie’s Planet and Terminations
30 May 2024
James Hansen

Antarctic (Dome C) temperature and Earth orbital parameters (1 kyr = 1000 years).

Sophie’s Planet and Terminations

30 May 2024

James Hansen

Writing of Sophie’s Planet is now proceeding at the pace (4 chapters per month) needed to finish it in 2024; I am into the second half of the book. The style is different than the version started years ago – most chapters now more compact and easier for the nonscientist to read. Nevertheless, it will contain a few chapters that are technical and challenging. Chapter 25 (Paleoclimate and “Slow” Feedbacks) is one of those, so I invite feedback on that chapter.

The time scale of “slow” feedbacks, including ice sheet disintegration, is a crucial issue that must be understand better to assess the climate threat. “Terminations,” the relatively rapid transitions from glacial to interglacial conditions, are an important source of knowledge about the physics of “slow” feedbacks. Human-made forcing driving the present transition from an interglacial to a super-interglacial – assuming we stay with our present ineffectual emissions reduction strategy – is more than an order of magnitude faster than the natural forcing that drove terminations, so the ongoing transition will be much faster than past terminations.

There is another reason to get into technical stuff on glacial-interglacial climate oscillations, besides the need to understand the physics of “slow” feedbacks. There are well-educated people ¹ who do not recognize how much is known from Earth’s climate history. Paleoclimate data show how sensitive climate is to forcings and the magnitude of the consequences, if the forcings are left in force long enough to bring “slow” feedbacks strongly into play. My aim is to describe the paleoclimate evidence well enough in just a few paleoclimate chapters that interested, objective, people will be able to appreciate the implications.

Why write a book that mixes climate science with a recounting of energy and climate policy travails? If mistakes of the past are not appreciated, it will be difficult to achieve a stable, beneficial, climate for future generations. The audience I hope to reach is especially young people. I am enthusiastic about the ability of student leaders to understand the climate situation and support the sort of policies that are needed, as I have mentioned in prior posts.²

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¹ I could point out a NASA Administrator who said, in effect: why worry about climate change – who are we to say that the present climate is the best one for humanity. But let’s not open old wounds.
² Hansen J. A realistic path to a bright future. 20 December 2021; Can young people save democracy and the planet? 8 October 2021

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