http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=table&application=fm08&convert=&converthl=&refinequery=&formintern=&formextern=&transquery=geoengineering&_lines=&multiple=0&descriptor=%2fdata%2fepubs%2fwais%2findexes%2ffm08%2ffm08%7c394%7c5221%7cInternational%20Collective%20Governance%20and%20the%20Need%20to%20Reduce%20Scientific%20Uncertainty%20about%20Geoengineering%7cHTML%7clocalhost:0%7c%2fdata%2fepubs%2fwais%2findexes%2ffm08%2ffm08%7c54481073%2054486294%20%2fdata2%2fepubs%2fwais%2fdata%2ffm08%2ffm08.txt
U41E-11 TI: International Collective Governance and the Need to Reduce Scientific Uncertainty about Geoengineering AU: * Ricke, K EM: [EMAIL PROTECTED] AF: Department of Engineering and Public Policy, Carnegie Mellon University, 5000 Forbes Ave, Baker 129, Pittsburgh, PA 15213, United States AU: Aina, T EM: [EMAIL PROTECTED] AF: Climateprediction.net Oxford e-Research Centre, University of Oxford, 7 Keble Road, Oxford, OX1 3QG, United Kingdom AU: Allen, M EM: [EMAIL PROTECTED] AF: Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom AU: Apt, J EM: [EMAIL PROTECTED] AF: Department of Engineering and Public Policy, Carnegie Mellon University, 5000 Forbes Ave, Baker 129, Pittsburgh, PA 15213, United States AU: Morgan, M EM: [EMAIL PROTECTED] AF: Department of Engineering and Public Policy, Carnegie Mellon University, 5000 Forbes Ave, Baker 129, Pittsburgh, PA 15213, United States AU: Steinbruner, J EM: [EMAIL PROTECTED] AF: School of Public Policy, University of Maryland, 2101 Van Munching Hall, College Park, MD 20742, United States AU: Stier, P EM: [EMAIL PROTECTED] AF: Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom AU: Victor, D EM: [EMAIL PROTECTED] AF: Program on Energy and Sustainable Development, Stanford University, Encina Hall E415, Stanford, CA 94305, United States AB: Geoengineering has been discussed for decades around the edges of the climate science community. However, today limited progress in abating emissions of GHGs makes the subject ever more salient. There is a growing need both for the foreign policy community to begin to consider how best to develop a framework for collective international governance of this issue, and to undertake research that will reduce uncertainty about the likely effectiveness and consequences of specific geoengineering technologies. In this paper we briefly outline insights on global governance gained from a workshop we to start a conversation about international governance that we convened at the Council on Foreign Relations in May 2008. This meeting's deliberations concluded that it is time to move studies of geoengineering and its impacts into mainstream research agendas. We outline some of the elements that such research should cover and then report on a study we are conducting based on simulations run using the climateprediction.net version of the coupled atmosphere-ocean general circulation model (AOGCM), Hadley Centre Coupled Model, version 3 (HadCM3) developed by the UK National Centre for Atmospheric Science. Past geoengineering modeling studies using AOGCMs have generally examined the effects of applying a constant geoengineering forcing. In this study we apply a range of 135 transient forcing scenarios designed to span the range of plausible uncertainties associated with countering anthropogenic GHG and sulfur aerosol forcings. Twin ensembles are being investigated for responses to IPCC A1B emissions scenario between 2000 and 2080, both with and without geoengineering activities starting in 2005. In our initial runs all models use identical parameter inputs, with the exception of an initial condition parameter. Geoengineering activities were mimicked in the models by modifying the volcanic aerosol radiative inputs, applied as variations in stratospheric optical depth over four zonal bands bounded by the equator, 30°N and 30°S. This work was supported by NSF cooperative agreement SES-034578. DE: 1600 GLOBAL CHANGE DE: 1620 Climate dynamics (0429, 3309) DE: 1626 Global climate models (3337, 4928) DE: 6309 Decision making under uncertainty DE: 6600 PUBLIC ISSUES SC: Union [U] MN: 2008 Fall Meeting [Comments. This appears to be associated with that transient modeling work I posted on about a week ago. The idea of transient geoengineering has some merit as does modulating its location, but the Brewer-Dobson circulation tends to spread precursor releases globally, so models that attempt to confine the aerosol to individual locations are probably invalid. Temporal variation, on the other hand, could be done, but there one has to be concerned about temperature spiking when the forcing is turned off. In general, aerosol precursor released into the Overworld stratosphere above 53,000 ft between 20N and 20S spreads globally and precursor released above those latitudes spreads only to the poles, not back to the tropics. Think of the Brewer-Dobson circulation as a waterfall that starts in the tropics and remember that water doesn't flow uphill. One idea I have been thinking about is what the impact would be on combining polar releases with tropical releases, such that more precursor is added to the polar region than would result from a tropical release only. The analogy would be that if Pinatubo and Novarupta simultaneously erupted. There are obviously lots of possibilities and even the 135 models mentioned in the abstract probably do not cover all of them. AG] http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=table&application=fm08&convert=&converthl=&refinequery=&formintern=&formextern=&transquery=geoengineering&_lines=&multiple=0&descriptor=%2fdata%2fepubs%2fwais%2findexes%2ffm08%2ffm08%7c390%7c2934%7cAcid%20Deposition%20From%20Stratospheric%20Geoengineering%20With%20Sulfate%20Aerosols%7cHTML%7clocalhost:0%7c%2fdata%2fepubs%2fwais%2findexes%2ffm08%2ffm08%7c54577785%2054580719%20%2fdata2%2fepubs%2fwais%2fdata%2ffm08%2ffm08.txt U43A-0041 TI: Acid Deposition From Stratospheric Geoengineering With Sulfate Aerosols AU: * Kravitz, B EM: [EMAIL PROTECTED] AF: Department of Environmental Science, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, United States AU: Robock, A EM: [EMAIL PROTECTED] AF: Department of Environmental Science, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, United States AU: Oman, L EM: [EMAIL PROTECTED] AF: Department of Earth and Planetary Sciences, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, United States AU: Stenchikov, G EM: [EMAIL PROTECTED] AF: Department of Environmental Science, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, United States AB: We used a general circulation model of the Earth's climate to conduct geoengineering experiments involving stratospheric injection of sulfur dioxide [Robock et al., 2008] and analyzed the resulting deposition of sulfate. When sulfur is injected into the tropical or Arctic stratosphere, the main additional surface deposition occurs in midlatitude bands, because of strong cross-tropopause flux in the jet stream regions, and there are some larger local increases, specifically in Northern Canada and the Western Pacific Ocean. We used critical load studies to determine the effects of this increase in acid deposition on terrestrial ecosystems. For annual injection of 5 Tg of SO2 into the tropical stratosphere or 3 Tg of SO2 into the Arctic stratosphere, the additional surface sulfate deposition is not enough to negatively impact most ecosystems. Robock, Alan, Luke Oman, and Georgiy Stenchikov (2008), Regional climate responses to geoengineering with tropical and Arctic SO2 injections. J. Geophys. Res., 113, D16101, doi:10.1029/2008JD010050. DE: 0345 Pollution: urban and regional (0305, 0478, 4251) DE: 1626 Global climate models (3337, 4928) DE: 1699 General or miscellaneous SC: Union [U] MN: 2008 Fall Meeting [Comment. And as I noted in my comments on the underlying paper, results from EPA's acid deposition monitoring program didn't detect a Pinatubo signature in 1992-1994, because the volcanic aerosol drop out was so much less than that from power plants. I also recommended that this analysis be carried out further, to see if there are any problems resulting from much larger aerosol loadings as the scenarios investigated assume an aerosol that would be more efficient in scattering sunlight than might be possible. The case against acid rain hasn't been totally put to bed, but it has been sent to its room and ordered to turn the lights out. AG] http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=table&application=fm08&convert=&converthl=&refinequery=&formintern=&formextern=&transquery=geoengineering&_lines=&multiple=0&descriptor=%2fdata%2fepubs%2fwais%2findexes%2ffm08%2ffm08%7c375%7c2904%7cGeoengineering%20of%20stratocumulus%20decks%20to%20counterbalance%20global%20warming:%20Pros%2c%20Cons%20and%20Side-Effects%7cHTML%7clocalhost:0%7c%2fdata%2fepubs%2fwais%2findexes%2ffm08%2ffm08%7c54476109%2054479013%20%2fdata2%2fepubs%2fwais%2fdata%2ffm08%2ffm08.txt U41E-09 TI: Geoengineering of stratocumulus decks to counterbalance global warming: Pros, Cons and Side-Effects AU: Haywood, J EM: [EMAIL PROTECTED] AF: Met Office, UK, FitzRoy Rd, Exeter, EX1 3PB, United Kingdom AU: Jones, A EM: [EMAIL PROTECTED] AF: Met Office, UK, FitzRoy Rd, Exeter, EX1 3PB, United Kingdom AU: * Boucher, O AF: Met Office, UK, FitzRoy Rd, Exeter, EX1 3PB, United Kingdom AB: Anthropogenic emissions of carbon dioxide from fossil-fuel burning are the primary cause of global warming and the projected rate of temperature change is very likely to increase in the future. Many geoengineering solutions have recently been suggested to reduce global warming. Here we use a state-of-the-science atmospheric general circulation model coupled to a mixed-layer ocean model to investigate the climatic impact of geoengineering via modifying stratocumulus decks. The model's climate is more than twice as sensitive to modification of the South Pacific stratocumulus area compared with the North Pacific or South Atlantic stratocumulus area. This strong sensitivity is associated with the cooling of sea-surface temperatures in the southern Pacific inducing patterns of temperature and precipitation response resembling La Niña conditions. If the southern Atlantic stratocumulus sheet is geoengineered, the model suggests an El Niño-like response with precipitation reduced by 15percent over South America as a whole, but a 30percent reduction over Amazonia. If all stratocumulus decks were geoengineered, the model suggests precipitation reductions of 15percent over South America, 9percent over North America, and 5percent over Europe and Asia. Thus the use of geographically inhomogenous radiative forcing mechanisms to counterbalance global warming induces distinct geographic responses in temperature and precipitation that may be very detrimental to some areas of the Earth. DE: 1630 Impacts of global change (1225) DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513) DE: 6309 Decision making under uncertainty SC: Union [U] MN: 2008 Fall Meeting [Comments. I'm unsure how much of these stratocumulus decks would be required to have their reflectivity increased to offset a given level of GHG forcing. Thus, is modeling based on the maximum whitening of all such clouds relevant other than to gauge the sensitivity of the climate system? If there is some precipitation reduction, then what is the threshold at which it becomes a problem? I don't have to remind everyone that the media tends to take the results of worst case models and present them as the most likely outcome. Latham's response to the IUSC discusses some of the sensitivity issues: quadrupling of brightness, level required to offset a doubling of CO2 or 1000ppm CO2, etc. as well as the impact on monsoonal flows and apparently El Ninos as well. Another idea. What would be the combined effects of cloud whitening and aerosol geoengineering? Nissen mentioned this and it was also mentioned in Watson's DEFRA response, I think. AG] --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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