Re: Paul Gambill posted new notes
3 views
Skip to first unread message
John Nissen
Nov 20, 2025, 7:03:16 AMNov 20
to Paul Gambill from Inevitable & Obvious, Planetary Restoration, Robin Collins, Ron Baiman
Hi again, Paul,
The danger from crossing 1.5C is not because of activating tipping element processes, but because the tipping processes may have reached a point of no return where collapse becomes inevitable, whatever we try to do. The reason I focus on the Arctic tipping points is that there are five tipping elements in the Arctic and the heating power there is even more concentrated than in the rest of the planet. This heating power mainly comes both from a combination of loss of albedo and from the incursion of warm water from the Atlantic and Pacific into the Arctic Ocean. Collapse is inevitable without cooling intervention. Collapse can only be avoided by providing greater cooling power than the above heating power. This may already be impossible, but we have to try our best, since a collapse of any one of the five tipping points, including the AMOC, would be catastrophic for the whole of humanity. Our best chance is by ramping SAI up as quickly as possible to a strength, and with a focus, sufficient to refreeze the Arctic. My letter to the FT was focussed on the collapse of the Greenland ice sheet, but the argument for emergency SAI applies to AMOC and the other tipping elements.
The CDR community will probably not have heard the above argument, but may be more receptive than most audiences because of being active in the field of climate change mitigation. CDR is a form of geoengineering necessary to remove legacy CO2 from the atmosphere and reduce its heating power of around 2.2 W/m2. SAI will be needed globally to counter this forcing. If SAI is to be phased out this century, CDR has to be ramped up to at least 60 GtCO2 removal for many decades.
Cheers, John
On Thu, Nov 20, 2025 at 8:18 AM Substack <no-r...@substack.com> wrote:
Paul Gambill posted new notes
© 2025 Substack Inc.
548 Market Street PMB 72296, San Francisco, CA 94104
Unsubscribe
%26strokeWidth%3D2){kind=small}
Reply all
Reply to author
Forward
0 new messages