Hi All
John Nissen writes below that marine cloud brightening is not so scalable as cloud coverage is limited.
Below is a table from Jones Haywood and Boucher of the UK Hadley Centre in the Journal of Geophysical Research 2009 showing 0.97 watts per square metre of cooling, about half the warming problem, could come from treating just 3.3% of the earth’s surface. This used the same spray regions all the year round but vessel mobility would allow us to track the movement of the best regions.

Charlson and Lovelock in Nature 326 pp 655-661, 1987 say that low but not high-level clouds cover 18% of the oceans.
I have sent some of you the attached calculations about sea level rise and would be grateful if you could suggest other input assumptions. Marine cloud brightening has the advantage of regional and seasonal control with high-frequency and low phase-lag.
Stephen
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Sent: Thursday, June 16, 2022 2:04 AM
To: Planetary Restoration <planetary-...@googlegroups.com>; Shaun Fitzgerald <sd...@cam.ac.uk>
Subject: PRAG meeting and SLR: Satellite images reveal dramatic loss of global wetlands over past two decades
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Hi everyone,
I'm in Canada for the next week without access to zoom so next Monday's meeting is cancelled.
I've had a chance to do a lot of reading and this paper (1) mentions the huge impact of sea level rise:
More than 1 billion people now live in low-elevation coastal areas globally.
The Greenland Ice Sheet could give us a sudden SLR of half a metre or more if glacier avalanches are triggered by dammed internal lake collapse or earthquake. To reduce this risk and the risk from growing extremes of weather/climate the Arctic must be cooled as quickly as possible.
Powerful intervention is mandatory. Stratospheric Aerosol Injection north of 50N is our best bet. It would be wonderful if the CCRC could endorse this strategy while SAI still has a good chance of success. Urgency cannot be overstated.
(MCB is not so scalable as cloud to brighten is limited. Using both SAI and MCB might be ideal, if MCB can be deployed quickly enough at strength. SAI has an advantage of the blanket cooling while MCB might provide more specific cooling where it helps.)
We need a campaign to recognise that SAI can be deployed extremely safely, mimicking a high latitude volcano such that ozone hole is not significantly affected and winter warming avoided.
The solution to the immediate climate emergency is so simple yet so far from being accepted let alone implemented - it's crazy.
Cheers John from mobile
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Renaud
I think that the reason for good cooling from spray under clear skies is that they were taking a long term average and spray under clear skies has longer to spread and a longer life. Double the drop number means a bit over 5% more reflectivity. Because of this log term in Twomey we want the low dose over a wide area that we get if we spray under clear skies. It is even better if we spray just after rain which has cleaned the air which will eventually get to somewhere with a high enough relative humidity. We are not in a hurry.
Stephen
Hi Renaud
Many thanks for this paper. It gives us references that also ISA probably produces this direct aerosol effect. Probably a little bit less because of the yellow-white ISA coloration. Within low humidity dry environments where no condensation can occure the ISA particles are also in a shrunk condition hence its color becomes lighter than in the expanded conditions at high humidity.
Franz
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On 16 Jun 2022, at 15:07, SALTER Stephen <S.Sa...@ed.ac.uk> wrote:
RenaudI think that the reason for good cooling from spray under clear skies is that they were taking a long term average and spray under clear skies has longer to spread and a longer life. Double the drop number means a bit over 5% more reflectivity. Because of this log term in Twomey we want the low dose over a wide area that we get if we spray under clear skies. It is even better if we spray just after rain which has cleaned the air which will eventually get to somewhere with a high enough relative humidity. We are not in a hurry.StephenFrom: Renaud de RICHTER <renaud.d...@gmail.com>
Sent: Thursday, June 16, 2022 2:22 PM
To: SALTER Stephen <S.Sa...@ed.ac.uk>
Cc: John Nissen <johnnis...@gmail.com>; Planetary Restoration <planetary-...@googlegroups.com>; Shaun Fitzgerald <sd...@cam.ac.uk>; geoengi...@googlegroups.com
Subject: Re: [geo] RE: PRAG meeting and SLR: Satellite images reveal dramatic loss of global wetlands over past two decadesThis email was sent to you by someone outside the University.You should only click on links or attachments if you are certain that the email is genuine and the content is safe.
Don't forget also Ahlm, L., Jones, A., Stjern, C. W., Muri, H., Kravitz, B., & Kristjánsson, J. E. (2017). Marine cloud brightening–as effective without clouds. Atmospheric Chemistry and Physics, 17(21), 13071-13087. https://acp.copernicus.org/articles/17/13071/2017/Sulfates from ships (and from fossil fuels power plants) are also effective without clouds!
Le jeu. 16 juin 2022 à 11:46, SALTER Stephen <S.Sa...@ed.ac.uk> a écrit :
Hi AllJohn Nissen writes below that marine cloud brightening is not so scalable as cloud coverage is limited.Below is a table from Jones Haywood and Boucher of the UK Hadley Centre in the Journal of Geophysical Research 2009 showing 0.97 watts per square metre of cooling, about half the warming problem, could come from treating just 3.3% of the earth’s surface. This used the same spray regions all the year round but vessel mobility would allow us to track the movement of the best regions.
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On 16 Jun 2022, at 18:33, Veli Albert Kallio <albert...@hotmail.com> wrote: