James Hansen's “Global Warming in the Pipeline” Abstract

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Dan Miller

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May 20, 2023, 4:02:52 PM5/20/23
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From James Hansen’s updated pre-print paper “Global Warming in the Pipeline”

Hard to think of a more impactful abstract that describes the future of our planet.  And most of this is not included in IPCC reports or is being considered by policymakers.

See my interpretations (for the public) here: https://twitter.com/danmiller999/status/1659986507137183744?s=20

Dan


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Ken Caldeira

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May 20, 2023, 4:50:10 PM5/20/23
to Dan Miller, CarbonDiox...@googlegroups.com
The IPCC gives a central estimate of equilibrium climate sensitivity for doubled CO2 of 3 C, with a "likely" range of 2.5 to 4 C, and a "very likely" range of 2 to 5 C.

The IPCC also gives 3.9 +- 0.5 W/m2 as the radiative forcing for a doubling of CO2.

image.png

 
Ken Caldeira
Senior Scientist (Emeritus)
Carnegie Institution for Science
Dept of Global Ecology
260 Panama St, Stanford CA 94305 USA

Senior Scientist, Breakthrough Energy:https://breakthroughenergy.org/our-team/ken-caldeira/


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Robert Chris

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May 20, 2023, 5:29:41 PM5/20/23
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Ken

I'd appreciate an explanation of the significance of your comment below.  This IPCC estimate is known, and acknowledged in the Hansen et al paper.  Are you affirming Hansen et al or refuting some aspect of their paper?  It would be helpful to understand why you felt the need to highlight this detail.

Regards

Robert Chris


Dan Miller

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May 20, 2023, 6:40:46 PM5/20/23
to Robert Chris, Ken Caldeira, Carbon Dioxide Removal
Hi Ken and Robert:

I’m sorry that my comment about the IPCC may sound misleading.  What I meant is that all of the conversation around climate, from the IPCC, the media, etc., is about staying under 2ºC, net zero by 2050, carbon budgets for 1.5ºC and 2ºC, etc.  It is all about the very short-term impact of GHGs.

Yet, what Hansen et al spell out is that when it comes to ECS, we are already at a doubling (the forcing is equivalent to a doubling of CO2 when all GHG are considered) and that the ECS implies 4.9ºC based on the current forcing (4.1 W/m^2) which is, in turn, based only on our past emissions! He goes to point out when long-term feedbacks are considered, we are on track for 8~10ºC without further emissions.

To me, this is a big disconnect.  Yes, humans are very short-term focused, but we should be talking about the slightly longer-term catastrophe we are setting up.  4.9ºC is “not compatible with an organized global community”. Thinking that we will stay under 2ºC by just lowering our emissions, as sea ice melts away, permafrost melts, and other near- and long-term feedbacks kick in, is not helping us act as we need to.

The IPCC may list the ECS, etc., but the narrative is all about near-term warming rather than warning us about the true implications of our past, current, and future emissions.

Dan

On May 20, 2023, at 2:29 PM, Robert Chris <robert...@gmail.com> wrote:

Ken

I'd appreciate an explanation of the significance of your comment below.  This IPCC estimate is known, and acknowledged in the Hansen et al paper.  Are you affirming Hansen et al or refuting some aspect of their paper?  It would be helpful to understand why you felt the need to highlight this detail.

Regards

Robert Chris



On 20/05/2023 21:49, Ken Caldeira wrote:
The IPCC gives a central estimate of equilibrium climate sensitivity for doubled CO2 of 3 C, with a "likely" range of 2.5 to 4 C, and a "very likely" range of 2 to 5 C.

The IPCC also gives 3.9 +- 0.5 W/m2 as the radiative forcing for a doubling of CO2.

<image.png>

 
Ken Caldeira
Senior Scientist (Emeritus)
Carnegie Institution for Science
Dept of Global Ecology
260 Panama St, Stanford CA 94305 USA

Senior Scientist, Breakthrough Energy:https://breakthroughenergy.org/our-team/ken-caldeira/

On Sat, May 20, 2023 at 1:02 PM Dan Miller <d...@rodagroup.com> wrote:
From James Hansen’s updated pre-print paper “Global Warming in the Pipeline”

Hard to think of a more impactful abstract that describes the future of our planet.  And most of this is not included in IPCC reports or is being considered by policymakers.

See my interpretations (for the public) here: https://twitter.com/danmiller999/status/1659986507137183744?s=20

Dan


<PastedGraphic-1.png>
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