We need SRM ….and CDR

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Greg Rau

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Jul 31, 2025, 11:26:32 PM7/31/25
to Geoengineering FIPC, Carbon Dioxide Removal
“ I've come to an uncomfortable but logical conclusion: temperature stabilization through cooling interventions will be required. Not as a replacement for emissions cuts or carbon removal, but to buy them time to succeed. Cooling is going to be needed, and what we must do now is evaluate which methods we'll use and how we'll govern them responsibly.”

Renaud de RICHTER

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Aug 4, 2025, 2:38:59 PM8/4/25
to Michael Hayes, Geoengineering FIPC, Bruce Melton -- Austin, Texas, Greg Rau

Le dim. 3 août 2025 à 22:36, Michael Hayes <electro...@gmail.com> a écrit :
Bruce, et al.,

Wood pulp in ice, or Pykrete, creates a stronger and longer lasting ice than typical. After reading your response above, it occured to me that Pykrete would end up sending lots of biomass to the seabed while possibly acting as a sponge for the ice ejected Ca CO3, microalgae, etc.. If the CaCO3 soaked biomass melts out and stays at the surface, the surface water will get a second shot at using the CaCO3.

Carbon negative sea ice production methods can be cool.

On Sun, Aug 3, 2025, 8:26 AM Bruce Melton -- Austin, Texas <bme...@earthlink.net> wrote:

Thanks Michael - and of course! The CO2 capture and sequestration mechanisms in sea ice ~ ~ ~

Those of you that live in limestone regions see the CaCO3 precipitate from local potable water ice in our drinks. A little white precipitate of Ca and other metals is often visible in the bottom of the glass. In the sea ice then, the free CO2, in the presence of concentrated salt exuded from freezing of salt water, creates more carbonates in the brine. Was there any quantification in any of these four papers? And did any look at the CO2 capture and sequestration quantity differences between sea ice formation and that of newly opened arctic waters?

To precipitate excess calcium in low pH limestone regions' potable water, alum is used. In high pH areas of igneous origins, lime is used.  But these processes are only so much efficient, leaving some carbonates remaining in the potable water ice to precipitate upon freezing.

MeltOn


On 8/1/2025 10:29 PM, Michael Hayes wrote:
SAI is the favorite go-to tech on the direct cooling topic, yet it is far from the only option. And, crossover techs, ones that have multiple benefits, are plausible.

As an example, sea ice production would provide both mCDR benefits and an albedo increase in key oceanic areas, and ice production is rather straightforward technology. 

Arctic Sea Ice: A Natural Ally in CO2 Reduction Efforts - Innovations Report https://share.google/NahHdgH6mOCjvHngT

On Thu, Jul 31, 2025, 8:26 PM Greg Rau <gh...@sbcglobal.net> wrote:
“ I've come to an uncomfortable but logical conclusion: temperature stabilization through cooling interventions will be required. Not as a replacement for emissions cuts or carbon removal, but to buy them time to succeed. Cooling is going to be needed, and what we must do now is evaluate which methods we'll use and how we'll govern them responsibly.”
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Ron Baiman

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Aug 4, 2025, 10:47:38 PM8/4/25
to Michael Hayes, Greg Rau, Geoengineering FIPC, Carbon Dioxide Removal, Michael MacCracken, Gregory Slater
Dear Michael et al., 
The key is the potential to have significant global impact in the near-term. Here's an (still in process) ordered chart of methods that the HPAC Urgent climate cooling Response WG has been working on: https://docs.google.com/presentation/d/1DK4OvG7bTG7wMUB7btYHOhxNCsNvbMH2/edit?usp=sharing&ouid=116465941111195452408&rtpof=true&sd=true
Here's the AGU 2025 abstract submission (with a title reminiscent of the opinion piece that Greg shared) that (if accepted) will draw on the final version of the powerpoint above: https://drive.google.com/file/d/1P4g5PtP5eBgsDlVdoXoGVcL0LQoe3SUG/view?usp=sharing
Best,
Ron

On Fri, Aug 1, 2025 at 10:29 PM Michael Hayes <electro...@gmail.com> wrote:
SAI is the favorite go-to tech on the direct cooling topic, yet it is far from the only option. And, crossover techs, ones that have multiple benefits, are plausible.

As an example, sea ice production would provide both mCDR benefits and an albedo increase in key oceanic areas, and ice production is rather straightforward technology. 

Arctic Sea Ice: A Natural Ally in CO2 Reduction Efforts - Innovations Report https://share.google/NahHdgH6mOCjvHngT

On Thu, Jul 31, 2025, 8:26 PM Greg Rau <gh...@sbcglobal.net> wrote:
“ I've come to an uncomfortable but logical conclusion: temperature stabilization through cooling interventions will be required. Not as a replacement for emissions cuts or carbon removal, but to buy them time to succeed. Cooling is going to be needed, and what we must do now is evaluate which methods we'll use and how we'll govern them responsibly.”

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Paul Stansell

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Aug 5, 2025, 8:55:57 AM8/5/25
to rpba...@gmail.com, Michael Hayes, Greg Rau, Geoengineering FIPC, Carbon Dioxide Removal, Michael MacCracken, Gregory Slater
Hello Ron,

Thanks for sharing your presentation.  I was a little disappointed to see MCB so low down your list of viable cooling options.  You have it at Option 8 out of 10 and you say it could produce "up to 0.2'C" of cooling by 2050.  I'd like to remind you that the heuristic model for MCB described in Wood 2021 suggests it may be feasible to use 12,000 MCB vessels to reflect 3.7 W/m2 (see Scenario 1 in Figure 5).  The value of 3.7 W/m2 is the power imbalance Wood assumes from a doubling of CO2 over pre-industrial times. Estimates of the temperature increase from doubling CO2 vary (e.g., 1.5'C to 4.5'C), but they are a lot higher than the 0.2'C you have in your table.  Why do you think there is such a difference?

Also, may I suggest that your presentation would benefit from a column for the "change in net radiative forcing" given as a global average in W/m2. 

Kind regards,

Paul 



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Michael MacCracken

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Aug 5, 2025, 1:34:27 PM8/5/25
to Paul Stansell, rpba...@gmail.com, Michael Hayes, Greg Rau, Geoengineering FIPC, Carbon Dioxide Removal, Gregory Slater

Dear Paul--As one of the contributors to the ranking, the table is focused on what could realistically be accomplished by 2050 in terms of achieved temperature moderation. 

Where the situation seems to be at present is the approach is being tested in Australia over the barrier reef and there really has yet to be resolved the range of conditions where it might have an effect and how the particular changes that would lead to cloud brightening can be distinguished from conditions that would lead to cloud reductions, how such conditions would be determined on a continuing basis, and lots more.

The next step in putting together materials is intended to be a table of approaches that would have the potential (by 2050) of having potentially beneficial outcomes on local to regional scales and in such a table for that I'd expect MCB to have a good bit higher rating, both because global approaches like SRM, methane reduction, general mitigation, etc. are not expected to provide specific benefits for particular locations/regions and because application at local/regional scales seems much more plausible than a global implementation.

Regards, Mike MacCracken

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