Thursday, February 12, 2015

Anti-‘Geoengineering’ National Academy Report Opposes ‘Climate-Altering Deployment’

Possible Ways to Reduce the Greenhouse Effect (Credit: NY Times) Click to Enlarge.
The U.S. National Academy of Sciences has released two very pessimistic reports on geoengineering.

Well, actually the reports are on “climate intervention,” because the Academy panel rejects the widely used term “geoengineering.”  Why?  Because “we felt ‘engineering’ implied a level of control that is illusory,” explained Dr. Marcia McNutt who led the report committee.  The word “intervention” makes it clearer that the “precise outcome” could not be known in advance

The first report is on Carbon Dioxide Removal and Reliable Sequestration, which covers everything that could permanently remove CO2 out of the air — from reforestation to direct capture of CO2 from the air.

The second report is on Reflecting Sunlight, which covers the more exotic climate-altering strategies to increase the reflectivity (albedo) of the Earth.  The best studied of these is injecting vast quantities of sulfate aerosols into the stratosphere to mimic the cooling effect of volcanos.  The authors also reject the widely used umbrella term for these strategies, “solar radiation management,” in favor of “albedo modification” because, again, “management” implies a level of control of the outcome that the committee does not believe we have.

Because of the problems with climate intervention, the scientists at the press conference echoed the central point the Academy makes in the report.  “There is no substitute for dramatic reductions in the emissions of CO2 and other greenhouse gases to mitigate the negative consequences of climate change, and concurrently to reduce ocean acidification,” the report read.  [One of the scientists has a Slate article:  Climate Hacking Is Barking Mad.]
[C]arbon capture and storage is expensive for coal plants.  But while extracting the carbon dioxide from coal burning (either pre-combustion or post-combustion) is certainly cheaper than any of the Carbon Dioxide Removal (CDR) strategies the Academy looked at, it doesn’t count as CDR itself because you are not removing net CO2 from the air with coal CCS (you are just not adding new CO2 into the air).  As you might expect, direct air capture — simply pulling massive amounts of CO2 out of the air — is incredibly expensive and difficult to scale given that atmospheric CO2 is so diffuse, only 400 parts per million.

The Academy explains further:
The barriers to deployment of CDR approaches are largely related to slow implementation, limited capacity, policy considerations, and high costs of presently available technologies.  Additional research and analysis will provide information to help address those challenges.  For these reasons, if carbon removal technologies are to be widely deployed, it is critical to embark now on a research program to lower the technical barriers to efficacy and affordability.  In the end, any actions to decrease the excess burden of atmospheric CO2 serve to decrease, or at least slow the onset of, the risks posed by climate change.  Environmental risks vary among CDR approaches but are generally much lower than the risks associated with albedo modification approaches.  However, it is also less risky environmentally to avoid a given CO2 emission to the atmosphere than to emit it with the expectation that it will be purposefully removed from the atmosphere at some later time.
Read more at Anti-‘Geoengineering’ National Academy Report Opposes ‘Climate-Altering Deployment’

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