Re: Clouds in the Arctic only provide cooling during a short period during the summer

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John Nissen

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Jun 2, 2023, 2:05:14 PM6/2/23
to Clive Elsworth, noac-m...@googlegroups.com, Planetary Restoration, healthy-planet-action-coalition, Brian von Herzen, David Mitchell, Peter Wadhams
Hi Clive,

At the HPAC meeting yesterday, there was a presentation on Cirrus Cloud Removal by David Mitchell.  Brian asked him about deployment, and David said that silver iodide could be used, though they did consider other compounds (I didn't catch the name of the compound he mentioned).

Whereas my calculations suggest that MCB, even at maximum strength, would be insufficient to refreeze the Arctic by itself, we need to pull out all the stops so I'd welcome continued research on deployment.  However the removal of high latitude clouds (of any altitude in the troposphere) in late autumn, winter and early spring could have a much more powerful cooling effect.  The realistic maximum effect needs to be calculated, for comparison with MCB.  I don't know whether Peter Wadhams has considered this.

BTW, I've long advocated cloud seeding over Greenland in winter,  Besides the cooling effect, it would move the ice sheet towards a net positive mass balance.  Fresh snow could also enhance albedo when diminished by black carbon and associated algal growth.

Cheers, John



On Fri, Jun 2, 2023 at 1:01 PM 'Clive Elsworth' via NOAC Meetings <noac-m...@googlegroups.com> wrote:

Thanks Stephen

 

I was wondering if anything other than cooling the flow of the oceans into the Arctic could help to cool Greenland ice outside the short period when MCB would work.

 

If droplet scavenging turns out to be effective, we may be able to do it over Greenland from drones or land-based stations, using our non-toxic white coloured Artificial Loess Dust aerosol that forms from vaporous chlorides and degenerates to clay after sedimenting.

 

Clive

 

From: noac-m...@googlegroups.com <noac-m...@googlegroups.com> On Behalf Of Stephen Salter
Sent: Friday, June 2, 2023 11:17 AM
To: 'Achim Hoffmann' <ac...@woxon.com>; 'Clive Elsworth' <Cl...@EndorphinSoftware.co.uk>; 'geoengi...@googlegroups.com' <geoengi...@googlegroups.com>; 'noac-m...@googlegroups.com' <noac-m...@googlegroups.com>
Subject: RE: Clouds in the Arctic only provide cooling during a short period during the summer

 

Clive

It is true and also rather obvious that cloud brightening only works in summer and this is taken in the calculations about the number of spray vessels which I have circulated. Please let me know if you would like me to send them again.

I agree that warm water in winter would be bad and so we should do marine cloud brightening at lower latitudes through the year.  This is a strong argument for vessel mobility.  The cooling will still be done but with a time delay.

If the Alterskjaer and Kristjansson are correct about Aitken mode aerosol  warming by clearing clouds because it removes lots of water without nucleation, then it might be possible to clear clouds in winter by spraying the very small aerosol.  The old design of spray vessels had 18 spray heads.  The present one has 32 so we could use smaller nozzles for part of the year.  We could also dilute salt water with some desalinated water or take water from what has melted from Iceland. It is only the mass of salt in the aerosol that matters.

 

Below are graphs from Curry about radiation levels through the year. Please let me know if you have any more recent data.

 

Stephen

 

 

From: noac-m...@googlegroups.com <noac-m...@googlegroups.com> On Behalf Of Achim Hoffmann
Sent: 01 June 2023 15:36
To: Clive Elsworth <Cl...@EndorphinSoftware.co.uk>; geoengi...@googlegroups.com; noac-m...@googlegroups.com
Subject: RE: Clouds in the Arctic only provide cooling during a short period during the summer

 

This 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.

Cooling the Oceans is a no-brainer, if it can be done.

 

There were a few recent publications talking about melting from “below”.

 

Here a recent WWF post including a Video explainer clearly targeted at the wider public (rather than experts).

https://www.arcticwwf.org/the-circle/stories/omg-greenlands-glaciers-are-melting-from-below/

 

From: 'Clive Elsworth' via NOAC Meetings <noac-m...@googlegroups.com>
Sent: Thursday, June 1, 2023 3:10 PM
To: geoengi...@googlegroups.com; noac-m...@googlegroups.com
Subject: Clouds in the Arctic only provide cooling during a short period during the summer

 

Hi Stephen – and cloud experts

 

I found this paper educational, by Shupe et al, 2004: Cloud Radiative Forcing of the Arctic Surface: The Influence of Cloud Properties, Surface Albedo, and Solar Zenith Angle:  https://journals.ametsoc.org/view/journals/clim/17/3/1520-0442_2004_017_0616_crfota_2.0.co_2.xml

 

It says low level clouds in the Arctic only provide cooling during a short period during the summer. The rest of the year they warm the Arctic. So presumably, as increasingly warmer seas flow into the Arctic these clouds will get thicker (i.e. greater Liquid Water Path – LWP) because the air will be more humid, making each cloud droplet bigger. So, it seems that to cool the Arctic the oceans need to be cooled.

 

Have I got that right?

 

Clive

 

From: noac-m...@googlegroups.com <noac-m...@googlegroups.com> On Behalf Of Stephen Salter
Sent: Thursday, June 1, 2023 2:18 PM
To: 'geoengi...@googlegroups.com' <geoengi...@googlegroups.com>; 'noac-m...@googlegroups.com' <noac-m...@googlegroups.com>
Subject: Overshoot

 

Hi All

The Nature paper by Richard Lovett at

https://www.nature.com/articles/d41586-023-01725-3?WT.ec_id=NATURE-202306&sap-outbound-id=DD2C61054D98C5BDD2C13072933E43E6D8C8E8F2

will annoy advocates for stratospheric sulphur more than those for marine cloud brightening.

It is a surprise to see this in Nature.

Stephen

 

>Nature - Overshoot

Yes a surprise, especially as it’s so easy to avoid another glacial period.

Clive

 

 

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