We need SRM ….and CDR

[Greg Rau]

https://www.inevitableandobvious.com/p/the-positive-case-for-global-cooling?utm_campaign=post&utm_medium=web

“ 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.”

[Conner Rudzinski]

Greg,

Solar geoengineering, while potentially useful against short-term temperature increases, carries risks that may not yet be fully understood and could result in unintended consequences. Efforts to buy time through SRM could potentially lead to costly remediation.

SRM primarily targets the reduction of peak daytime surface temperatures (Tmax) by limiting incoming solar radiation. However, it does not address the rising minimum nighttime temperatures (Tmin), which are a significant driver of global warming trends. During nighttime hours, Earth releases heat via infrared radiation. Greenhouse gases such as carbon dioxide, methane, and water vapor absorb this radiation and re-emit it toward the surface, limiting surface cooling. SRM may not be effective in counteracting this.

This report (https://www.ipcc.ch/report/ar6/wg1/) highlights this; It estimates a global average Tmax increase of 0.88 °C per century, compared to a more pronounced Tmin rise of 1.86 °C per century.

Although CO2 capture progress is moving slowly, it still has potential to make a significant impact if appropriately prioritized.

Thanks,

Conner

On Thu, Jul 31, 2025 at 11:26 PM Greg Rau <gh...@sbcglobal.net> wrote:

https://www.inevitableandobvious.com/p/the-positive-case-for-global-cooling?utm_campaign=post&utm_medium=web

“ 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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[Tom Goreau]

Minimum temperatures are rising faster than maximum temperatures, reducing the daily temperature range.

 

Increased night time temperatures mean higher CO2 losses from respiration, reducing net production. This causes biological carbon cycle feedbacks on land and sea that amplify global warming.

 

When I lived in Manaus, Amazonia, I was surprised that mangoes in Manaus bore fruit infrequently despite equatorial temperatures. Mangoes sold in the streets were largely imported from the colder south of Brazil, where low night time temperatures caused less respiration carbon losses, and therefore higher productivity.

 

At sea, as on land, minimum temperatures are rising faster than maximum temperatures, reducing coral ability to recover from bleaching:

 

T. J. Goreau, R. L. Hayes, J. W. Clark, D. J. Basta, & C. N. Robertson, 1993, Elevated sea surface temperatures correlate with Caribbean coral reef bleaching, p. 225-255 in R. A. Geyer (Ed.), A GLOBAL WARMING FORUM: SCIENTIFIC, ECONOMIC, AND LEGAL OVERVIEW, CRC Press, Boca Raton, Florida.

 

Thomas J. F. Goreau, PhD
President, Global Coral Reef Alliance

Chief Scientist, Biorock Technology Inc., Blue Regeneration SL

Technical Advisor, Blue Guardians Programme, SIDS DOCK

37 Pleasant Street, Cambridge, MA 02139

gor...@globalcoral.org
www.globalcoral.org
Phone: (1) 857-523-0807 (leave message)

 

Books:

Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase

https://www.routledge.com/Geotherapy-Innovative-Methods-of-Soil-Fertility-Restoration-Carbon-Sequestration-and-Reversing-CO2-Increase/Goreau-Larson-Campe/p/book/9781466595392

 

Innovative Methods of Marine Ecosystem Restoration

https://www.taylorfrancis.com/books/oa-edit/10.1201/b14314/innovative-methods-marine-ecosystem-restoration-robert-kent-trench-thomas-goreau

 

Geotherapy: Regenerating ecosystem services to reverse climate change

 

No one can change the past, everybody can change the future

 

It’s much later than we think, especially if we don’t think

 

Those with their heads in the sand will see the light when global warming and sea level rise wash the beach away

 

“When you run to the rocks, the rocks will be melting, when you run to the sea, the sea will be boiling”, Peter Tosh, Jamaica’s greatest song writer

 

“The Earth is not dying, she is being killed” U. Utah Phillips

 

“It is the responsibility of intellectuals to speak the truth and expose lies” Noam Chomsky

 

 

 

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[Michael Hayes]

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:

https://www.inevitableandobvious.com/p/the-positive-case-for-global-cooling?utm_campaign=post&utm_medium=web

“ 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.”

--

[Bruce Melton -- Austin, Texas]

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

Bruce Melton PE
Director, Climate Change Now Initiative, 501c3
President, Melton Engineering Services Austin
8103 Kirkham Drive
Austin, Texas 78736
(512)799-7998
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Inst...@Bruce.C.Melton
The Band Climate Change
Twitter - BruceCMelton1 

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[Michael Hayes]

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.

[Ron Baiman]

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

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--

Healthy Planet Action Coalition

YouTube Channel

@HPACoalition  (Bluesky and Twitter/X)

 Addressing the Urgent Need for Direct Climate Cooling: Rationale and Options

Baiman et al. 2024. Oxford Open Climate Change

An 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

[Michael MacCracken]

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

On 8/5/25 8:29 AM, Paul Stansell wrote:

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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