Ken et al.--I have done a similar calculation with MAGICC‹and when you do the full set of gases, note that tropospheric ozone and black carbon drop very quickly as well, and methane over a couple of decades, so there is an offset to the sulfate warming if we can reduce those other forcings.
And on the rapidity of the response, note that for volcanic forcings, one gets a pretty quick response, at least of the mixed layer. If one is up to an equilibrium, then it would take a lot longer to get the heat out of the deeper ocean layers. Mike MacCracken On 6/12/09 12:02 AM, "Ken Caldeira" <[email protected]> wrote: > I note that Tom got greater cooling than we got in Matthews and Caldeira for a > related scenario. (We ignored sulfur and non-CO2 greenhouse gases.) > > Our paper was done using the UVic model and its thermal response seems > sluggish when compared to other models, so Tom's results may well be correct. > > I am surprised that the cessation of sulfur emissions did not cause more of an > overshoot. > > > > ___________________________________________________ > Ken Caldeira > > Carnegie Institution Dept of Global Ecology > 260 Panama Street, Stanford, CA 94305 USA > > [email protected]; [email protected] > http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab > +1 650 704 7212; fax: +1 650 462 5968 > > > > On Thu, Jun 11, 2009 at 10:15 PM, Tom Wigley <[email protected]> wrote: >> John, >> >> You are wrong. If we stop all emissions immediately, the warming >> trend will stop and reverse. In the attached ms I set all emissions >> to zero from 2021 onwards. >> >> Tom. >> >> +++++++++++++++++++++++ >> >> John Nissen wrote: >>> > >>> > No, it's all wrong - about the CO2 being absorbed from the atmosphere >>> > and the planet cooling. On the contrary, if we were all to drop dead >>> > tomorrow, global warming would continue for thousands of years, as I >>> > explain in the thread I started, about the GREAT LIE. There'd also be >>> > an immediate warming spurt, as the sulphur aerosol pollution (which has >>> > a cooling effect) would be quickly washed out of the atmosphere. >>> > And,within a few decades, on top of the CO2 warming would be the warming >>> > from methane as permafrost melted, and the sea level would rise 60-70 >>> > metres as Greenland and Antarctic ice sheets melted. >>> > >>> > Thus, if we disappear, or just carry on as we are for that matter, the >>> > Earth will continue tipping into a super-hot state, which probably won't >>> > be habitable for humans, even at the poles. However it is unlikely that >>> > the Earth will go the way of Venus, with the oceans boiling away, if >>> > that's any comfort. >>> > >>> > Cheers, >>> > >>> > John >>> > >>> > --- >>> > >>> > Alvia Gaskill wrote: >>>> >> http://en.wikipedia.org/wiki/Aftermath:_Population_Zero >>>> >> >>>> >> I recently saw the Nat. Geo program "Aftermath: Population Zero," one >>>> >> of several hypothetical accounts of what the world would be like >>>> >> without people. Not less people, no people. These seem to have been >>>> >> inspired by the work of Alan Weisman, author of the book "The World >>>> >> Without Us." >>>> >> >>>> >> http://en.wikipedia.org/wiki/The_World_Without_Us >>>> >> >>>> >> In addition to describing what would happen to domesticated animals >>>> >> and pets left without humans to take care of them, the fate of >>>> >> infrastructure is also presented. This particular program (there is >>>> >> another one that has been turned into a series on the History Channel >>>> >> called, appropriately enough, "Life After People" >>>> >> http://en.wikipedia.org/wiki/Life_After_People ; >>>> >> http://en.wikipedia.org/wiki/Life_After_People:_The_Series [for those >>>> >> people still not depressed enough after watching the original >>>> >> documentary]) also explores changes in the Earth's climate without its >>>> >> number one interferent, us. >>>> >> >>>> >> After 150 years, winters are colder than during the last days >>>> >> of humans with greater snowfall, indicating declining GHG levels. It >>>> >> is stated that the oceans will remove 13.5Gt of CO2 per year. Is this >>>> >> correct? >>>> >> >>>> >> After 200 years, the excess CO2 from human emissions is completely >>>> >> eliminated by plants and trees. Don't tell David Archer. Perhaps the >>>> >> increase in plant growth will speed the removal. Or won't that matter? >>>> >> >>>> >> After 500 years, forests return to the state they had 10,000 years >>>> >> ago. I doubt that one, as that would have been at the tail end of the >>>> >> ice age. >>>> >> >>>> >> After 25,000 years, the interglacial is over, the ice sheets return >>>> >> and erase NYC along with most of the areas wiped out before. Which >>>> >> raises an interesting question for the geo haters. If it became >>>> >> apparent that the interglacial was ending, would you be in favor of >>>> >> artificial means of prolonging it to ensure the planet's habitability >>>> >> for billions of humans? If you say no, then I think I'm going to >>>> >> propose to Nat. Geo or History a new series, Life After YOU People! >>>> >> >>>> >> >>>> >> >>>> >> >>>> >> >>> > >>>> > > >> >> >> > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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