Opinion Top British climate boffins have said that the only practical hope for arresting global warming is the use of "geoengineering" - techniques intended to reduce the effects of CO2 emissions, as opposed to reducing the CO2 emissions themselves.
The scientists add that not only are large emissions cuts politically and diplomatically unfeasible, but that geoengineering would actually be cheaper and easier.
The new arguments come from Professor Peter Cox, Met Office Chair in climate system dynamics at Exeter Uni, and Hazel Jeffery, a major bigwig at the UK Natural Environment Research Council. The pair presented the case for geoengineering in an article for Physics World yesterday.
Following on from a recent review of geoengineering techniques carried out for the Royal Society, Cox and Jeffery outline the various strategies which have been put forward - generally efforts to remove carbon from the atmosphere or to reflect sunlight back into space.
According to the two scientists, so-called "conventional mitigation" - that is, the curbing of CO2 emissions - is highly unlikely to be implemented effectively by the whole human race, and even if it is it won't work.
Even if global CO2 emissions are cut by 50% by 2050, this now seems unlikely to be enough to keep global warming below 2°C this century ... global CO2 emissions have continued to climb despite growing concerns over climate change. Given that conventional mitigation now appears insufficient to avoid dangerous climate change, do we have a plan B? This is the motivation for geoengineering.
Cox and Jeffery say that most climate scientists have until lately refused to discuss geoengineering as it might seem to allow continued or even increased carbon emissions - generally seen as totally unacceptable among specialists in the field.
Discussion of geoengineering proposals remained taboo among mainstream climate scientists until 2006... The primary reason there has been so little debate about geoengineering amongst climate scientists is concern that such a debate would imply an alternative to reducing the human carbon footprint.
Bitchslap for white roofs and artificial trees
The pair seem to back up the worst fears of conventional climate scientists, by saying - more or less - that it would be cheaper for the human race to carry on emitting carbon as much as we like and save the planet using geoengineering, as compared to cutting CO2 emissions. A renewables or nuclear powered world using electric or hydrogen transport would be much more expensive to implement than a coal and oil burning civilisation with global warming controlled by an upper-atmosphere particulate sunscreen, for instance.
While some approaches, such as ocean fertilization or white-roof techniques, can be ruled out because they are unlikely to have a significant global climate benefit, most of the geoengineering proposals appear cheap compared with conventional mitigation. More importantly, many have a higher climate benefit to annual cost ratio than conventional mitigation...
The estimated costs of maintaining a sulphate aerosol shield, most likely through a small number of dedicated high-flying aircraft, are remarkably cheap compared with the costs of conventional mitigation by factors of hundreds or even thousands.
The Institution of Mechanical Engineers will be cross, as they have recently suggested that white roofs would be a good notion. In the same document, the IMechE also said that extraction of CO2 from the atmosphere for sequestration underground would be a brilliant plan.
Cox and Jeffery disagree, however, saying that artificial trees and sequestration would be even more expensive than cutting emissions. The only advantage of the scheme would be that it probably couldn't have unforeseen negative side-effects as with the upper-atmos particulate planes notion. But one could say the same of cutting emissions, which would be cheaper than artificial trees - and yet still so expensive as to mean that it can't happen.
The safest alternative to conventional mitigation is CO2 air capture, which removes the primary cause of global warming and therefore avoids the risks associated with termination, regional climate change and ocean acidification. Currently, however, air capture appears expensive relative to conventional mitigation and very expensive relative to large-scale techniques for solar-radiation management.
Essentially, according to the two boffins, the only planet-saving plans the human race is likely to actually carry out are those which are significantly cheaper and more convenient than conventional emissions cuts. Such plans would appear to offer the only realistic way that a very serious temperature rise can be avoided: so in fact, they should be the main stream of climate science - rather than on the fringe as they are now.
"For scientists who want to save the planet, there should be no more attractive research field than geoengineering," the pair write. ®