Re: House of Commons Session in Geoengineering (15/7/09)
John,
A quick note. I hope I was saying that, if you believe the
models which seem OK for temperatures, the sulphur scheme
would cool the poles, and the rest of the planet more.
Both Rasch's results and those of Lund (bristol) showed this.
However, the cooling associated with the cloud whitening scheme,
is especially pronounced at the pole (as shown by Rasch and our HaDGAM
results) and therefore could help preserve the permafrost.
I am afraid I have little faith in the precipitation from climate
models, especially in the tropics. Parts of India have predictive errors
of over 2m per year for current simulations. With doubling CO2
there will be precipitation shifts, definitely. Cloud whitening is likely
to have them too, but hopefully will counterbalance the increasing CO2
shifts.
I think it is important not to jump in too soon, but examine with models
and small experiments the viability of schemes. I appreciate that
some (well Steven Rayner) at the meeting called me a "climate porn
merchant" ... and many other "jibes" , and I was also called a
"scaremongerer", but I feel it would be of advantage to take as many
people forward as possible, and explore all the facets of each approach.
NERC and EPSRC are preparing initiatives, and I do agree it is
urgent. There may ( or may not) be ozone depletion problems with
significant use of sulphates, so we must take care.
Cheers
Alan
On Tue, 21 Jul 2009, John Nissen wrote:
>
> Hi all,
>
> Recently the geoengineering group discussed the pros and cons of solar
> radiation management (aka SRM geoengineering) using stratospheric
> aerosols in the Arctic [1].
>
> A possible downside of more widespread deployment of stratospheric
> aerosols has come to light; it is from decreased rainfall on Amazon
> [2]. Some of us were already concerned by possible slight weakening of
> monsoons.
>
> This decreased rainfall is liable to be aggravated by the growing El
> Nino. (The last strong one was in 1998.)
>
> Yet some experts (e.g. Jeff Ridley) are saying that deployment in the
> Arctic will not be sufficient to save the sea ice. (And if the sea ice
> goes, the methane could come out of permafrost, Greenland ice sheet
> disintegrate, etc.)
>
> And Alan Gadain, from the University of Leeds was warning me, last week
> [3], that Arctic deployment wouldn't work, yet on the other hand an
> effect of more general deployment would be to cool the Arctic.
>
> Who is right, and what should we do?
>
> Could there be a way to protect Amazon and elsewhere from reduced
> rainfall, while deploying stratospheric aerosols at a range of latitudes
> to produce both widespread cooling effect and specific cooling in the
> Arctic?
>
> We could use marine cloud brightening rather than stratospheric
> aerosols, because the risk of undesirable side effects is smaller and
> because the technique can be applied locally, but do we have the luxury
> of time to develop the technique? The Arctic sea ice is liable to
> disappear more rapidly than anyone expected - we just cannot predict
> with any certainty. Likewise the Amazon rainforest could perish if
> there were consecutive years of drought - which we cannot predict.
>
> Isn't there an overwhelming case for some kind of experimental trial of
> stratospheric aerosols in the Arctic, preferably starting next spring,
> before El Nino effects set in? There is so much at stake, wouldn't it
> be stupid to delay?
>
> And shouldn't some significant funding be put into marine cloud brightening?
>
> Cheers from Chiswick,
>
> John
>
> [1] "Balancing the pros and cons of geoengineering" thread:
> http://groups.google.com/group/geoengineering/browse_thread/thread/b045b6428fc89a93/95b940c3c3352e35?#95b940c3c3352e35
>
> [2] Aerosol effects investigated by Met Office:
> http://www.metoffice.gov.uk/corporate/pressoffice/2009/pr20090604.html
>
> [3] Geoengineering seminar at the House of Commons, 15th July 2009.
>
>
>
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