Dear John‹A couple of comments: 1. Indeed, keeping the Arctic cold and keeping summer sea ice go hand in hand. So, yes, I certainly want to keep summer sea ice around (what would actually be helpful is to have thin sea ice in the winter so the heat held by the ocean could be conducted through the sea ice and radiated to space, making the ice thicker). 2. On the issue of the paper just dealing with solar radiation management, my talk in Copenhagen in March 2009 and the World Bank report that I prepared on geoengineering for the World Sustainability Report I had a fourth category devoted to reducing CO2, which I agree is also essential. This was not covered in the paper as the paper was long enough as it was and I am not as knowledgeable on that area, but I certainly agree we want to keep CO2 down. As long as global fossil fuel emissions are heading upward toward 10 GtC/yr and then higher, however, it is hard to see how pulling CO2 from the atmosphere is going to have enough of an effect to make a significant difference-we have to get emissions down to deal with CO2 related issues such as acidification, and keeping sea ice from melting is going to take geoengineering, at the pace we are going (the only other alternative is really cutting the non-CO2 GHG emissions and soot to zero quickly as their radiative forcing can go down faster than the rise in forcing due to rising CO2, at least for a short time. You can see my thoughts on dealing with short-lived GHGs at http://www.climate.org/PDF/MacCracken_Erice.pdf
Mike On 11/1/09 1:53 PM, "John Nissen" <j...@cloudworld.co.uk> wrote: > > Thanks for the reference to the Environmental Research Letters, David. > > Only Mike MacCracken's paper considers the context for geoengineering. If we > are going to have to use geoengineering to tackle certain problems, how should > we approach it. He considers three problem areas: > 1) the warming of low-latitude oceans which contribute to more intense > tropical cyclones and coral bleaching; > 2) the amplified warming of high latitudes and the associated melting of ice > that has been accelerating sea level rise and altering mid-latitude weather; > 3) the projected reduction in the loading and cooling influence of sulphate > aerosols, which has the potential to augment warming sufficient to trigger > methane and carbon feedbacks. > > I would suggest that the amplified warming of (2) has the potential to trigger > massive methane discharge (and associated positive feedback on global warming) > of (3) as well as the potential to trigger rapid sea level rise. The retreat > of Arctic sea ice is part of the warming amplification process, so it is > crucial to prevent its summer disappearance. Do you agree, Mike? > > If you agree, then the importance of this (i.e. preventing Arctic sea ice > summer disappearance) makes the arguments against geoengineering in the other > papers seem rather irrelevant! > > Note that Mike has only considered the problems that could be addressed with > SRM geoengineering. If we consider problems such as ocean acidification, and > addressing them with techniques such biochar, then the arguments in the other > papers against geoengineering seem irrelevant to the point of absurdity - but > then perhaps the arguments were directed at SRM geoengineering alone. > > Cheers from Chiswick, > > John > > --- > > David Keith wrote: >> >> >> >> Folks, >> >> >> >> There is a set of papers on geoengineering on line at Environmental Research >> Letters. Ken Caldeira and I served as editors of this special issue. More >> papers and a editorial will be added later. >> >> >> >> Cheers, >> >> David >> >> >> >> >> >> http://www.iop.org/EJ/abstract/1748-9326/4/4/045101 >> >> >> >> Focus on Climate Engineering: Intentional Intervention in the Climate System >> >> 2009 Environ. Res. Lett. 4 045101 doi: 10.1088/1748-9326/4/4/045101 >> <http://dx.doi.org/10.1088/1748-9326/4/4/045101> >> <http://www.iop.org/EJ/help/-topic=abstract/abstract/1748-9326/4/4/045101> >> >> >> Geoengineering techniques for countering climate change have been receiving >> much press recently as a `Plan B' if a global deal to tackle climate change >> is not agreed at the COP15 negotiations in Copenhagen this December. However, >> the field is controversial as the methods may have unforeseen consequences, >> potentially making temperatures rise in some regions or reducing rainfall, >> and many aspects remain under-researched. >> >> >> This focus issue of Environmental Research Letters is a collection of >> research articles, invited by David Keith, University of Calgary, and Ken >> Caldeira, Carnegie Institution, that present and evaluate different methods >> for engineering the Earth's climate. Not only do the letters in this issue >> highlight various methods of climate engineering but they also detail the >> arguments for and against climate engineering as a concept. >> >> >> Further reading >> Focus on Geoengineering at >> http://environmentalresearchweb.org/cws/subject/tag=geoengineering >> IOP Conference Series: Earth and Environmental Science is an open-access >> proceedings service available at www.iop.org/EJ/journal/ees >> <http://www.iop.org/EJ/journal/ees> >> >> >> Focus on Climate Engineering: Intentional Intervention in the Climate System >> Contents >> >> >> Modification of cirrus clouds to reduce global warming >> <http://www.iop.org/EJ/abstract/1748-9326/4/4/045102> >> David L Mitchell and William Finnegan >> >> >> Climate engineering and the risk of rapid climate change >> <http://www.iop.org/EJ/abstract/1748-9326/4/4/045103> >> Andrew Ross and H Damon Matthews >> >> >> Researching geoengineering: should not or could not? >> <http://www.iop.org/EJ/abstract/1748-9326/4/4/045104> >> Martin Bunzl >> >> >> Of mongooses and mitigation: ecological analogues to geoengineering >> <http://www.iop.org/EJ/abstract/1748-9326/4/4/045105> >> H Damon Matthews and Sarah E Turner >> >> >> Toward ethical norms and institutions for climate engineering research >> <http://www.iop.org/EJ/abstract/1748-9326/4/4/045106> >> David R Morrow, Robert E Kopp and Michael Oppenheimer >> >> >> On the possible use of geoengineering to moderate specific climate change >> impacts <http://www.iop.org/EJ/abstract/1748-9326/4/4/045107> >> Michael C MacCracken >> >> >> >> >> >> >> > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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