Re: Invitation to co-sign an open letter supporting applied-science testing and piloting of near-term global climate cooling
Ron Baiman
Dear Colleagues,
We invite you to join us in signing this: Open Letter in Support of Applied-Science Testing and Piloting of Near-term Global Climate Cooling Approaches: (https://docs.google.com/document/d/1-ylFDVmw362TQmKxmmH1_NTlw7k-RHMS/edit?usp=sharing&ouid=116465941111195452408&rtpof=true&sd=true) in which we stress that if we're going to start "shaving the peak" in 2030-2050, as many global climate model geoengineering simulations assume, we need to start working on this now, or, at least, as soon as possible.
As many of you know we have been working on this letter for many months. During this time it has undergone numerous revisions in response to extensive feedback from numerous colleagues - some among the current signatories and some not. We believe at this point that further editing has reached a point of diminishing returns and that it is time to move forward on garnering further support in advance of (hopeful) publication.
We think that this letter could be an important component of the political effort to open the Overton Window that we and our near allies have expanded to include general support for geoengineering "research," but that continues to be firmly shut on the issue of "piloting." The following quote, for example, is from the September 2023 Executive Summary of the Climate Overshoot Commission ( https://www.overshootcommission.org/_files/ugd/0c3b70_bab3b3c1cd394745b387a594c9a68e2b.pdf):
"Countries should adopt a moratorium on the deployment of solar radiation modification and large-scale outdoor experiments that would carry risk of significant transboundary harm, while expanding research, and pursuing international governance dialogues."
We disagree with this formulation as it appears to fail to take into account the ever larger catastrophic climate events that will happen if cooling efforts are not initiated in the very near future. Both "large outdoor" applied-science testing and piloting of near-term global climate cooling approaches need to start now in order to be implemented in the 2030s at the latest.
Some of you are likely familiar with the general position in favor of urgent climate cooling being implemented as a complementary approach to more aggressive efforts to cut emissions of CO2 and CH4, increase resilience, and initiate efforts to build up Carbon Dioxide Removal.. We believe that our open letter sharpens our call for a credible comprehensive approach to controlling climate change and clarifies the practical implications of the need for adding urgent near-term global cooling to the active set of policy options.
With the global temperature increase poised to speed past the aspirational goal of the Paris Accord, we are asking for your signature in support of countering voices that see efforts to augment and complement emissions reduction with carefully research cooling influences as more risky than continuing toward projected global warming of 2 to even 3°C or more of global warming, as argued, for example, in Siegert et al. (2025), who asserted that
"… further research into these [geoengineering] techniques would not be an effective use of limited time and resources.” [brackets ours].
Finally, this letter is part of a parallel effort to transmit a position paper with a similar message to IPCC delegations in advance of COP-31, for which, needless to say, broad support for this letter would be helpful.
We encourage you to consider co-signing this letter if you agree with the need to augment COP’s mitigation-focused approach that, while essential to reduce peak warming, is proving insufficient to meet the goals of the Paris Accord, much less pull the world back from likely exceeding an increasing number of irreversible tipping points.
To indicate your concurrence, please send a note to Ron Baiman at rpba...@gmail.com (also copying Michael MacCracken at mmac...@comcast.com). Please include your name as you would like it to appear and your affiliation(s), including other affiliations than just HPAC.
Thank you,
Best,
Ron and Mike
For the Co-Signers
--@HPACoalition (Bluesky and Twitter/X)2025 Baiman, MacCracken and Slater. AGU PosterBaiman et al. 2024. Oxford Open Climate ChangeAn Open Letter to the IMO Supporting Maritime Transport that Cools the Atmosphere While Preserving Air Quality Benefits. Baiman et al. 2024. Oxford Open Climate Change
rob...@rtulip.net
Hi Ron, happy to sign. I have suggested some typographical and clarity changes in revision mode in the attached copy. Also suggested some deletions as the letter is long.
Regards
Robert Tulip
Ron Baiman
Ron Baiman
From: Ron Baiman <rpba...@gmail.com>
Date: Wed, Feb 18, 2026 at 1:56 PM
Subject: Re: Invitation to co-sign an open letter supporting applied-science testing and piloting of near-term global climate cooling
Cc: Michael MacCracken <mmac...@comcast.net>
Dear Colleagues,Thank you again to all who have signed!We now have 30 signatures and just need 12 more to achieve our goal of 42 (see p. 7): https://docs.google.com/document/d/1-ylFDVmw362TQmKxmmH1_NTlw7k-RHMS/edit?usp=sharing&ouid=116465941111195452408&rtpof=true&sd=truePlease consider signing if you haven't yet! The sooner we get to our goal the sooner this will be submitted and (hopefully) published.Best,Ron and MikeOn Mon, Feb 16, 2026 at 5:14 PM Ron Baiman <rpba...@gmail.com> wrote:Dear Colleagues,I've been encouraged to send out this motivational blurb and invitation to sign the HPAC "Open Letter in Support of Applied-Science Testing and Piloting of Near-term Global Climate Cooling Approaches" again.Our goal is 42 signatures (to match Siegert et al. 2025) and we currently have 15 (see p. 7 of letter), so need 27 more.Thank you!Best,Ron
---------- Forwarded message ---------
From: Ron Baiman <rpba...@gmail.com>
Date: Tue, Feb 10, 2026 at 12:41 PM
Subject: Invitation to co-sign an open letter supporting applied-science testing and piloting of near-term global climate cooling
Dear Colleagues,
We invite you to join us in signing this: Open Letter in Support of Applied-Science Testing and Piloting of Near-term Global Climate Cooling Approaches: (https://docs.google.com/document/d/1-ylFDVmw362TQmKxmmH1_NTlw7k-RHMS/edit?usp=sharing&ouid=116465941111195452408&rtpof=true&sd=true) in which we stress that if we're going to start "shaving the peak" in 2030-2050, as many global climate model geoengineering simulations assume, we need to start working on this now, or, at least, as soon as possible.
As many of you know we have been working on this letter for many months. During this time it has undergone numerous revisions in response to extensive feedback from numerous colleagues - some among the current signatories and some not. We believe at this point that further editing has reached a point of diminishing returns and that it is time to move forward on garnering further support in advance of (hopeful) publication.
We think that this letter could be an important component of the political effort to open the Overton Window that we and our near allies have expanded to include general support for geoengineering "research," but that continues to be firmly shut on the issue of "piloting." The following quote, for example, is from the September 2023 Executive Summary of the Climate Overshoot Commission ( https://www.overshootcommission.org/_files/ugd/0c3b70_bab3b3c1cd394745b387a594c9a68e2b.pdf):
"Countries should adopt a moratorium on the deployment of solar radiation modification and large-scale outdoor experiments that would carry risk of significant transboundary harm, while expanding research, and pursuing international governance dialogues."
We disagree with this formulation as it appears to fail to take into account the ever larger catastrophic climate events that will happen if cooling efforts are not initiated in the very near future. Both "large outdoor" applied-science testing and piloting of near-term global climate cooling approaches need to start now in order to be implemented in the 2030s at the latest.
Most of you are likely familiar with the general HPAC position in favor of urgent climate cooling being implemented as a complementary approach to more aggressive efforts to cut emissions of CO2 and CH4, increase resilience, and initiate efforts to build up Carbon Dioxide Removal.. We believe that our open letter sharpens our call for a credible comprehensive approach to controlling climate change and clarifies the practical implications of the need for adding urgent near-term global cooling to the active set of policy options.
With the global temperature increase poised to speed past the aspirational goal of the Paris Accord, we are asking for your signature in support of countering voices that see efforts to augment and complement emissions reduction with carefully research cooling influences as more risky than continuing toward projected global warming of 2 to even 3°C or more of global warming, as argued, for example, in Siegert et al. (2025), who asserted that
"… further research into these [geoengineering] techniques would not be an effective use of limited time and resources.” [brackets ours].
Finally, this letter is part of a parallel effort by HPAC’s Steering Circle to transmit a position paper with a similar message to IPCC delegations in advance of COP-31, for which, needless to say, broad support for this letter would be helpful.