[BWB Note: I'm a bit tight for time right now, but Andrew Glikson saves the day with another great post, this time elaborating on some of the 'options' we made need to face if we delay too long in cutting carbon emissions. For earlier discussions of this topic on BraveNewClimate, see here and here.]
Guest post by Andrew Glikson (Andrew is an Earth and paleo-climate scientist, Australian National University who contributes regularly to Brave New Climate).
That global climate change has reached an impasse whereby the “powers-to-be” are entertaining climate geoengineering mitigation, instead of the urgent deep reduction of carbon emissions required by science, represents the ultimate moral bankruptcy of institutions and a failure of democracy.
With global atmospheric CO2 levels rising at about 2 ppm/year toward 388 ppm, or near-440 ppm CO2-e (including methane effects), John Holdren, in his first interview since being appointed as Obama’s new science adviser, revealed in an interview with AP (8 April, 09) “global warming is so dire, the Obama administration is discussing radical technologies to cool Earth’s air” which “as an experimental measure would only be used as a last resort … It’s got to be looked at … We don’t have the luxury of taking any approach off the table … One such extreme option includes shooting pollution particles into the upper atmosphere to reflect the sun’s rays“. Holdren compared the way humanity is facing dangerous climate change to passengers in a car with bad brakes heading toward a cliff in a fog, saying “The sensible passengers will certainly say: ‘Let’s put on the brakes, even if we don’t know it will save us. It may be too late. We don’t know exactly where the cliff is. . . . Let’s get on with it.’ “.
Holdren is not alone in considering geoengineering. The National Academy of Science is also looking at the subject in its new multidiscipline climate challenges program. The American Meteorological Society is preparing a statement on geoengineering, stating “it is prudent to consider geoengineering’s potential, to understand its limits and to avoid rash deployment.”.The British parliament has discussed the idea.
Climate geoengineering ideas fall into at least four principal categories:
(1) Increased reflectivity (albedo) of the atmosphere, injecting sulphur dioxide (suggested by Paul Crutzen, the Nobel Prize winning atmospheric chemist), or alumina particles, or even installing reflectors in space. The effects of sulphur injections would simulate volcanic events, such as of Pinatubo (1991) or Tambora (1816), which resulted in cooling of the Earth surface by about 0.5 degrees. At best, albedo enhancement represents a short term band aid solution to the fundamental greenhouse problem, and will not be able to prevent ocean acidification.
(2) Increased sequestration of CO2 in the oceans, enhancing algal blooms and phytoplankton photosynthesis through fertilization with iron filings, or constructing vertical pipe systems designed to enhance oceanic circulation and CO2 intake from the atmosphere.
(3) Biochar burial and soil enrichment. Combustion of plant waste under low oxygen conditions and burial as charcoal, removing carbon from atmospheric circulation and enhancing plant growth and photosynthesis, as well as soil enrichment. A major controversy erupted with objections to Biochar by George Monbiot, involving James Lovelock and James Hansen.
(4) Chemical sequestration involving combination of CO2 with sodium hydroxide (NaOH) installed in pipe systems (“Sodium trees”), followed by separation and burial of CO2, costed at about $US300 a ton. A back-of-the-envelope calculation suggests the reduction of atmospheric CO2 by 50 ppm would cost about $US 10 — 15 trillion (although mass production may lessen the cost, as well as contribute to employment), less than 10 times the global military expenditure in 2007.
Increasingly, a “technological fix” may look attractive to Obama and possibly the EU (and Rudd?), in view of at least three major obstacles to CPRS and ETS schemes:
First, due to the cumulative nature of atmospheric CO2, neither 5/15% nor 25/40% emission reduction by 2020 relative to 2000 would be able to prevent major climate change. This is because CO2 levels, now at 387 ppm and rising by 2 ppm/year, will exceed 400 ppm by 2020, well into the high danger zone. Assuming CO2 emissions are reduced by even 40% relative to 2000, it would keep rising by a minimum of 1.2 ppm/year reaching levels near or above 450 ppm by 2050, and this is without even accounting for the effects of methane, likely reduced CO2 intake by the oceans and increase in positive feedbacks from the biosphere. At 450 ppm, with lag effects, polar ice sheets undergo advanced melting, with consequent major sea level rise. It is not clear how many of the submissions made to the Australian Senate Inquiry into the CPRS take account of this factor.
Filed under: Clim Ch Q&A, Future | 29 Comments »
