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Will Geo-Engineering Get Us Out of a Potential One-Way Street?
Coming on the heels of the Lohafex study which found that iron fertilization in the Southern Ocean did not fix significant amounts of carbon, this article from Foreign Affairs ($ubscription required, full text article available from the lead-author's website) is interesting. The idea is that even if all CO2 emissions were stopped, it would be a long time before the atmospheric CO2 concentrations decrease to pre-industrial levels. The authors advocate that geo-engineering is to be taken seriously, even if we do not end up deploying it. The article notes that options such as albedo enhancers (increasing the amount of solar energy reflected to outer space), iron fertilization of oceans are being touted as solutions. The authors also point out that whereas reaching a consensus on a globally-binding CO2 limiting agreement involves multilateral discussions, the geoengineering option on the other hand is less costly to be deployed by a single country, often without regard to other countries' interests. Because humans are already engaged in a large-scale geophysical experiment by pumping CO2 into the atmosphere, the authors note that reducing emissions would not likely suffice to prevent drastic climate change, and hence geo-engineering might become more attractive as policy makers confront this scenario.
On a related topic, in a recent paper published in the Proceedings of the National Academy of Sciences (PNAS, USA), Solomon et al. indicate that if CO2 concentrations in the atmosphere (currently at 385 ppm) peak to 450-600 ppm (despite zero CO2 emissions) and atmospheric temperatures would not drop significantly for at least a century. Irreversible dry-season rainfall reductions are one of the impacts predicted by their modeling study.
My comments:
Although geo-engineering through albedo enhancers may decrease atmospheric temperatures, it does not directly reduce the amount of CO2 in the atmosphere. Additionally, a recent study found that the use of albedo enhancers will limit the amount of sunlight available to plants. Other techniques such as iron fertilization are highly controversial, and as the Lohafex trial concluded, are likely to be only marginally beneficial. On the other hand, even if the major CO2 emitters reduce their emissions, it is likely that CO2 levels in the atmosphere will be high enough to worry policymakers in various countries to consider the extreme step of modifying the climate to fix the climate. To prepare for this eventuality, increased scientific collaboration on geo-engineering should be encouraged, so that the risks of various approaches can be evaluated.
Other articles of interest:
Tim Lenton and Nem Vaughan. The radiative forcing potential of different climate geo-engineering options. Atmospheric Chemistry and Physics Discussions, January 28, 2009
On a related topic, in a recent paper published in the Proceedings of the National Academy of Sciences (PNAS, USA), Solomon et al. indicate that if CO2 concentrations in the atmosphere (currently at 385 ppm) peak to 450-600 ppm (despite zero CO2 emissions) and atmospheric temperatures would not drop significantly for at least a century. Irreversible dry-season rainfall reductions are one of the impacts predicted by their modeling study.
My comments:
Although geo-engineering through albedo enhancers may decrease atmospheric temperatures, it does not directly reduce the amount of CO2 in the atmosphere. Additionally, a recent study found that the use of albedo enhancers will limit the amount of sunlight available to plants. Other techniques such as iron fertilization are highly controversial, and as the Lohafex trial concluded, are likely to be only marginally beneficial. On the other hand, even if the major CO2 emitters reduce their emissions, it is likely that CO2 levels in the atmosphere will be high enough to worry policymakers in various countries to consider the extreme step of modifying the climate to fix the climate. To prepare for this eventuality, increased scientific collaboration on geo-engineering should be encouraged, so that the risks of various approaches can be evaluated.
Other articles of interest:
Tim Lenton and Nem Vaughan. The radiative forcing potential of different climate geo-engineering options. Atmospheric Chemistry and Physics Discussions, January 28, 2009
