Hi Alvia--Thanks for comment and making report more accessible. I would just note that there is no reason one has to think one would keep putting out SO2 emissions from power plants--why mix it with dark aerosols? Emissions could be of pure SO2 (given all the sulfur that has been scavenged) and does not have to be done where people are--or in conditions that lead to rainout of large amounts in sensitive areas, etc. And SO2 does not have to be put out continuously or during times of low or no sunlight. Balloons holding hoses aloft to a kilometer or so would likely be all that would be needed in a few places--and like a kite, pull the balloon down when a storm comes as it does no good to put out SO2 into a rain storm (of course, choose sites where there are few storms). And I would add we know a good deal about the effects of SO2 in the atmosphere, though surely not enough (like what have been the radiative and meteorological effects of the center of S emissions moving from North Atlantic basin to southeastern Asia--so at lower latitude with more solar effect, but we don't know emissions inventory real well--both amount and altitude of emissions).
I like the Salter and Latham approach, but it works only on some types of clouds and relatively limited area--SO2 works in more types of clouds over broader area and also has effect in clear air. Of course, SO2 does have more side effects (health, ecosystems, etc.) so I would have to design the system to minimize those (e.g., encouraging sulfate build-up over dark and remote ocean areas for global effect where there are no solar direct technologies being used)--stratospheric aerosols have much lower effects on health and ecosystems, but would have significant effect on direct solar technologies if they are dispersed globally. As we are learning, there is no such things as a free lunch, so we need to consider the price and quality of all the various lunches available. Mike On 6/17/09 7:29 AM, "Alvia Gaskill" <[email protected]> wrote: > Your paper wasn't that easy to find, but find it I did. An excellent review > of most of the major geoengineering proposals and some I hadn't heard about > before. I'm still opposed to allowing SO2 emissions from power plants to > continue, however. I renamed the file for ease of recognition. > > Summary: Global climate change is occurring at an accelerating pace, and the > global greenhouse gas (GHG) emissions that are forcing climate change > continue to increase. Given the present pace of international actions, it > seems unlikely that atmospheric composition can be stabilized at a level > that will avoid "dangerous anthropogenic interference" with the climate > system, as called for in the UN Framework Convention on Climate Change. > Complicating the situation, as GHG emissions are reduced, reductions in the > offsetting cooling influence of sulfate aerosols will create an additional > warming influence, making an early transition to climate stabilization > difficult. With significant reductions in emissions (mitigation) likely to > take decades, and with the impacts of projected climate change-even with > proactive adaptation-likely to be quite severe over the coming decades, > additional actions to offset global warming and other impacts have been > proposed as important complementary measures. Although a number of possible > geoengineering approaches have been proposed, each has costs and side > effects that must be balanced against the expected benefits of reduced > climate impacts. However, substantial new research is needed before > comparison of the relative benefits and risks of intervening is possible. A > first step in determining whether geoengineering is likely to be a useful > option is the initiation of research on four interventions to limit the > increasing serious impacts: limiting ocean acidification by increasing the > removal of carbon dioxide from the atmosphere and upper ocean; limiting the > increasing intensity of tropical cyclones; limiting the warming of the > Arctic and associated sea level rise; and sustaining or enhancing the > existing sulfate cooling influence. In addition, in depth consideration is > needed regarding the governance structure for an international > geoengineering decision-making framework in the event that geoengineering > becomes essential. > > http://econ.worldbank.org/external/default/main?pagePK=64165259&theSitePK=4693 > 72&piPK=64165421&menuPK=64166093&entityID=000158349_20090519141020 > > http://www-wds.worldbank.org/external/default/WDSContentServer/IW3P/IB/2009/05 > /19/000158349_20090519141020/Rendered/PDF/WPS4938.pdf > > https://blogs.worldbank.org/climatechange/geoengineering-possible-climate-chan > ge-insurance-policy > > Geoengineering: A Possible Climate Change Insurance Policy? > By Michael MacCracken > Created 06/15/2009 - 18:24 > > > > Even if all emissions of greenhouse gases and aerosol precursors ended > today, more warming would occur in coming decades than the 0.8°C that has > occurred to date, greatly intensifying climate change and its associated > impacts. Already, sea level is rising, sea ice and mountain glaciers are > retreating, the ranges of plant and animal species are shifting poleward and > upward, and the Greenland and Antarctic ice sheets are both losing mass. > Each round of the assessments of the Intergovernmental Panel on Climate > Change has found that change is occurring more rapidly than previously > projected. > > With coal, petroleum, and natural gas providing over 80% of the world's > energy, greenhouse gas emissions cannot be stopped today, or next year, or > even in a few decades. While international negotiations have the potential > to limit emissions and the ultimate changes in climate to be experienced by > future generations, much greater changes in climate than have occurred to > date are inevitable, and their impacts will continue to intensify. The > changes are so rapid and large that it is becoming much more likely that > critical thresholds will be exceeded, triggering potentially unstoppable > Earth system responses. Most serious would be initiation of large releases > of methane from thawing permafrost or sea level rise of over a meter per > century as deterioration of the major ice sheets accelerates. The resources > required to deal with the consequences if this occurs would be enormous. > > While limiting emissions through mitigation is essential and can help slow > climate change, the problem is that just reducing emissions will only very > slowly limit climate change over the next few decades. And while adaptation > is also essential, there are many consequences of climate change for which > no practical adaptive response exists-societies will have to suffer, > migrate, or find new ways to provide the lost services. With international > negotiations moving slowly, the situation continues to become more and more > problematic. > > The urgency of the situation has resurrected consideration about whether it > might be appropriate to not just limit what we are doing to the climate, > but, in addition, to attempt to deliberately manipulate the climate and/or > atmospheric composition in a way that would counteract the changes being > induced by the energy-related emissions of carbon dioxide and other > greenhouse gases. This category of effort has been dubbed geoengineering, > although it might better be termed georestoring of the climate, because the > intent would be to moderate climate change and its impacts. > > For example, nations might choose to try to emulate the cooling influence of > major volcanic eruptions by, on a continuing basis, augmenting the amount of > particulate matter in the stratosphere. Injecting sulfate aerosols globally > or at the right latitudes could be done in a way that would reflect an > amount of solar radiation equal to the increased trapping of energy by the > greenhouse gases. Although this could limit global warming, thus reducing > impacts like the loss of sea ice and slow the increase in sea level, there > would be several side effects, including whitening of the sky, perhaps > altering the course of storm systems, and reducing the efficiency of many > types of solar energy systems. While this might seem an acceptable tradeoff > today, it is worth noting that future generations would have to continue > these injections for centuries, or the warming that was being offset would > reappear relatively rapidly. The report, Beyond Mitigation: Potential > Options for Counter-Balancing the Climatic and Environmental Consequences of > the Rising Concentrations of Greenhouse Gases, just published provides an > overview of the range of proposals that have been made over the past few > decades. > > In addition to limiting global change through mitigation, a conceivable > complementary approach could be to augment the international approach could > be augmented with specially designed efforts to limit the intensity of > specific, particularly severe impacts. In my view, four possible actions > deserve intense analysis because the potential losses appear to be far > larger than the likely cost of implementation: > > 1.. Limiting the solar radiation that reaches the Arctic and Antarctic in > order to restore conditions needed by the region's species and to limit sea > level rise from the melting of the Greenland and West Antarctic Ice Sheets. > 2.. Enhancing uptake of carbon by the ocean, storing it in the deep ocean > in order to moderate ocean acidification and limit damage to the marine food > web. Alternatively, ocean acidification might be limited in specific areas > such as the Great Barrier Reef by adding a buffering compound to ocean > waters. > 3.. Limiting the warming of the ocean in the regions that contribute to > intensification of tropical cyclones (i.e., hurricanes, typhoons, etc.). > 4.. Actively managing the global emissions of sulfur dioxide in order to > maintain, or even enhance, the global cooling influence of tropospheric > aerosols. > Each of these actions, and there may be others worthy of consideration, > would focus on intervening to moderate a specific impact. There are viable > technological approaches for each of these activities, and they would be > readily reversible if unexpected, adverse consequences arose. What is needed > now is an aggressive research and development effort that determines the > optimum approach, carries out small scale tests, investigates and compares > unintended side effects with the impacts of greenhouse gases that are > alleviated, and puts forth a near-term plan for active consideration at an > appropriate regional or global forum. > > None of these actions would be a substitute for aggressive global mitigation > of emissions or alleviate all of the adverse consequences. However, they > could more evenly spread the burden of global warming and potentially slow > the onset of at least some of the irreversible consequences. In this way, > geoengineering could buy a small amount of time for global mitigation to be > negotiated and take hold. Undertaking research on these impact interventions > seems important and timely. > > > > ----- Original Message ----- > From: "Mike MacCracken" <[email protected]> > To: "Geoengineering" <[email protected]> > Sent: Wednesday, June 17, 2009 12:31 AM > Subject: [geo] World Bank posting > > >> >> You might be interested in the World Bank posting at >> https://blogs.worldbank.org/climatechange/ >> >> It is an intro and pointer to a background report that reviews many of the >> possibilities for geoengineering prepared in support of the major World >> Bank >> report to be issued on Sustainability and Climate Change. >> >> Best, Mike MacCracken >> >> >> >> >> --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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