Dear Ken,
thanks a lot to Matthias, to translate the article!
I think it is important to point out that there is very likely a limit
on how much the Earth's surface could be cooled using sulfate aerosols,
due to coagulation processes and fall out of aerosols. Only less than 2
W/m2 reduction of global net surface SW flux was achieved in the study
by Heckendorn et al., 2009, using a micro-physical model to consider
size distributions of the aerosols. Niemeier et al., 2010, achieved a
stronger forcing if injecting particles at 30hPa, which allow them to
stay longer in the stratosphere. Though it will be hard to inject
particles that high.
Cheers, Simone
References:
Niemeier, U., H. Schmidt and C. Timmreck, The dependency of
geoengineered sulfate aerosol on the emission strategy, Atmos. Sci.
Let., DOI: 10.1002/asl.304, 2010.
Heckendorn P, Weisenstein D, Fueglistaler S, Luo BP, Rozanov E, Schraner
M, Thomason LW, Peter T. 2009. The impact of geoengineering aerosols on
stratospheric temperature and ozone.
Environmental Research Letters 4: 045108. DOI: 10.1088/1748-9326/4/4/045108.
Simone,
Not reading German, I don't know precisely what is in the story.
What I said to the reporter is that if the aerosol layer similar to that
of Mt Pinatubo were sustained, it would produce a cooling of about 3 K.
This is based on estimates of Mt Pinatubo producing around 4 W / m2 of
radiative forcing (cf. Crutzen, 2006?), which is similar to a CO2
doubling -- and 3 C per CO2 doubling is in the middle of the range of
estimates for climate sensitivity. So, this is just a back-of-envelope
calculation.
A question of course, given particle aggregation and so on, is whether
such a layer could be sustained.
Best,
Ken
On Thu, Jun 28, 2012 at 6:37 PM, Simone Tilmes <[email protected]
<mailto:[email protected]>> wrote:
Dear Ken,
in the article you stated that Mt Pinatubo is assumed to result in a
global cooling of about 0.5 degree. It is also stated in the text of
the article that the amount of aerosols emitted, if they would stay
in the stratosphere for a longer time period, would result in a 3
degrees global cooling. Could you point me to the study you are
referring to that calculates this amount of cooling if injecting
volcanic aerosols of the amount of Mt Pinatubo?
Cheers, Simone
Ken
It should follow from your argument about the land-sea temperature
difference reducing precipitation on land that a technique which
had the
initial effect of cooling the sea would be more attractive. If
it were
also possible to have a frequency response shorter than the monsoon
cycle we could play useful tricks about the phase of operations
relative
to the monsoon season.
Stephen
Emeritus Professor of Engineering Design
Institute for Energy Systems
School of Engineering
Mayfield Road
University of Edinburgh EH9 3JL
Scotland
Tel +44 131 650 5704 <tel:%2B44%20131%20650%205704>
Mobile 07795 203 195
www.see.ed.ac.uk/~shs <http://www.see.ed.ac.uk/~shs>
On 28/06/2012 06:27, Ken Caldeira wrote:
pdf attached.
http://www.nzz.ch/wissen/__wissenschaft/sonnenschutz-__fuer-die-erde-1.17282213
<http://www.nzz.ch/wissen/wissenschaft/sonnenschutz-fuer-die-erde-1.17282213>
_______________
Ken Caldeira
Carnegie Institution for Science
Dept of Global Ecology
260 Panama Street, Stanford, CA 94305 USA
+1 650 704 7212 <tel:%2B1%20650%20704%207212>
[email protected]
<mailto:[email protected]>
<mailto:kcaldeira@__carnegiescience.edu
<mailto:[email protected]>>
http://dge.stanford.edu/labs/__caldeiralab
<http://dge.stanford.edu/labs/caldeiralab> @kencaldeira
*Currently visiting * Institute for Advanced Sustainability
Studies
(IASS) <http://www.iass-potsdam.de/>
*and *Potsdam Institute for Climate Impact Research (PIK)
<http://www.pik-potsdam.de/>*__in Potsdam, Germany.*
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