Re: The Surprisingly Simple Approach To Save The Arctic And The World
John Nissen
A vicious cycle of warming and melting has built up in the Arctic, partly due to albedo positive feedback but also aggravated by the entry of warm Atlantic and Pacific waters into the Arctic Ocean. The cycle has to be broken and waters cooled before the Arctic can be refrozen. Our group, PRAG, has already produced a review of methods for refreezing the Arctic which was presented at AGU 2020. Since then our focus has been on the two most powerful methods: marine cloud brightening (MCB) using seawater to create cloud condensation nuclei; and stratospheric aerosol injection (SAI) using SO2 to create a reflective aerosol haze. MCB is known to work because of ship trails. But the technology now being developed relies on the production of droplets in a certain critical size range, and the technology to produce them is yet to be demonstrated on a sufficient scale to brighten clouds. The potential is to provide local cooling but there is dependency on suitable marine cloud availability over large enough areas to cool the Arctic and surface water flowing into the Arctic. On the other hand SAI has the prime exemplar of large volcanic eruptions producing SO2 in the stratosphere which can be monitored for cooling effect. The spreading of the SO2 by stratospheric circulation produces a blanket cooling effect suitable for cooling the whole planet or just the poles. There is no problem of scalability as enough SO2 can be supplied to produce whatever blanket cooling is required. MCB can be added for local cooling. Deployment costs are estimated to be in the tens of billions of dollars per year, whereas the costs in the absence of such cooling run into trillions of dollars per year and millions of lives.
The Pinatubo eruption in June 1991 produced about 0.5°C of global cooling over two years. On the downside it produced some ozone depletion. A recent research study suggests that SAI with injection poleward of 60° could cool the poles by 2°C with only a small manageable risk from ozone depletion. The injection would be during late spring and early summer such that almost all the aerosol would leave the stratosphere within two or three months due to Brewer-Dobson circulation. This should almost entirely avoid ozone depletion since the reaction that causes the ozone hole is a cold temperature reaction which occurs at the end of winter when the upper stratosphere is coldest. The objective would be a blanket cooling over the whole polar region: this would increase the pole-to-tropics temperature gradient thereby reducing extremes of weather and climate produced by Arctic amplification. Injection poleward of a lower latitude, e.g. 50° rather than 60°, would do more to cool the sub-polar regions, stabilise the GIS, and slow release of methane from permafrost.
Hitherto, the idea of SAI has been met with extreme scepticism by the scientific community. Our examination of the evidence finds that SAI is potentially benign. A realistic reassessment is urgently required, since calculations may find that SAI is the only cooling technique with enough power to refreeze the Arctic.
--This seems like a PR release, I’m surprised Stephen Salter and Peter Wadhams are not mentioned?
From: healthy-planet-...@googlegroups.com <healthy-planet-...@googlegroups.com> on behalf of rob...@rtulip.net <rob...@rtulip.net>
Date: Friday, December 2, 2022 at 1:58 PM
To: 'H simmens' <hsim...@gmail.com>, 'healthy-planet-action-coalition' <healthy-planet-...@googlegroups.com>
Subject: RE: The Surprisingly Simple Approach To Save The Arctic And The WorldThanks Herb, here is a comment I have added at Medium. Text of the article is attached.
Hi Will, thanks, this is a great article. I work on MCB and found your simple explanation illuminating. It is great to see Cambridge taking up the science and the advocacy. We need to brighten the planet to stop climate tipping points. As well as helping with the climate problems you mention, MCB in the Atlantic would cut the intensity of hurricanes, and Arctic MCB and refreezing would stabilise the jet stream. Note the 7m sea level rise you mention is just from Arctic ice, Antarctica has ten times as much ice! I live in Australia, where an MCB trial is in progress to save the Great Barrier Reef from coral bleaching. Testing MCB in the Southern Ocean might be easier to agree on than in the Arctic, so I am calling on the Australian government to lead this discussion. MCB and other albedo technologies offer a paradigm shift in climate policy. Cutting emissions is not enough.
Robert Tulip
From: healthy-planet-...@googlegroups.com <healthy-planet-...@googlegroups.com> On Behalf Of H simmens
Sent: Friday, 2 December 2022 11:35 PM
To: healthy-planet-action-coalition <healthy-planet-...@googlegroups.com>
Subject: The Surprisingly Simple Approach To Save The Arctic And The World
MCB is ‘the surprisingly simple approach’ that Will Lockett advocates in this short post. He focuses on the work being done on MCB at the Cambridge Centre for Climate Repair. Our own HPAC member Stephan Salter is, as many of you know, a pioneer in bringing MCB to fruition.
Our next HPAC meeting on December 15 will feature Dr Shaun Fitzgerald, the Director of the Centre. More information to come.
Many thanks to Brian and the distinguished group of biochar veteran experts for a stimulating, almost two hour discussion at yesterday’s HPAC meeting. The recording will be circulated shortly.
Herb
Herb Simmens
Author A Climate Vocabulary of the Future
@herbsimens
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