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Geoengineering - a last ditch response to climate change?

In its recent report on geo-engineering, the Royal Society argues that “air capture” carbon dioxide absorption techniques are probably the best geo-engineering option in that we should “address the root cause of climate change by removing greenhouse gases from the atmosphere”. Solar heat reflector techniques were seen as generally less attractive. It may well be true that carbon dioxide absorption is the best type of geo-engineering option,but surely, geo-engineering of whatever type in no way deals at source with the “root cause” of climate change – which is the production of carbon dioxide in power stations, gas boilers and vehicles.

The Royal Society report, like the parallel report from the Institution of Mechanical Engineers, does stress that “No geo-engineering method can provide an easy or readilyacceptable alternative solution to the problem of climate change” and that mitigation and adaptation programmes are vital. However, there is the risk that “technical fix” geo-engineering approaches may be seized on as an alternative to dealing with the problem at source, since they could seem to offer ways to allow continued use of fossil fuels. That’s not to say there is no role for geo-engineering, but we need a hierarchy of options.

Mitigation via renewables would come top of my list, along with improved energy efficiency. Adaptation will inevitably have to occur – given the emissions that we have already produced, whatever we do about mitigation, or for that matter geo-engineering, we are going to be faced with some climate change. Geo-engineering, as a pretty inelegant “end of pipe”, trying to clean up “after the event” approach, might be seen as an ancillary option, rather than as a last line of defence, or as “Plan B”.

Tim Fox, who led the IMechE study, commented sensibly that “We’re not proposing that geo-engineering should be a substitute for mitigation [but] should be implemented alongside mitigation and adaptation. We are urging government not to regard geo-engineering as a plan B but as a fully integrated part of efforts against climate change.”

Even so, there are major uncertainties over costs, reliability and eco-impacts, as both reports recognised. Both proposed a £10 m pa UK research programme, which seems not unreasonable, to try to identify the best options and the risks more clearly. But let’s not get too deflected from what ought to be the primary aim of avoiding carbon dioxide release in the first place.

Prof. John Shepherd, from Southampton University, who chaired the Royal Society’s study, said: “It is an unpalatable truth that unless we can succeed in greatly reducing CO₂ emissions, we are headed for a very uncomfortable and challenging climate future. Geo-engineering and its consequences are the price we may have to pay for failure to act on climate change.”

Fair enough. But, if we really are worried about climate change, it would be better if we got seriously stuck into mitigation, and didn’t have to add to our problems by launching potentially risky large-scale geo-engineering programmes.

Of course not all will be risky – though they still may not be wise. It was good to see re-afforestation mentioned by the Royal Society as an option, even if it could only realistically absorb a smallish proportion of our ever-increasing emissions. However, while the IMechE backed the idea of painting roof tops white to reflect solar heat and reduce global or least local heating, the Royal Society said: “The overall cost of a ‘white roof method’ covering an area of 1% of the land surface would be about $300 billion/yr, making this one of the least effective and most expensive methods.” Putting solar collectors on roof-tops might be a better idea! I’m not so sure about chemical air capture though. Both reports back the “Artificial Tree” idea for carbon dioxide absorption. Submarines, and, famously, Apollo spacecraft, used sodium, hydroxide to do this. If we are thinking along the same lines now for the whole planet, we must be getting desperate. Biochar might be a better option – but not if on a very large scale, surely?

Geo-engineering may have a role, and these reports are useful, but there are still a lot of unknowns – after all its basically about tinkering further with the climate and linked ecosystems, albeit consciously rather than accidentally. Quite apart from the cost, there is the risk that, if we adopt large-scale programmes like seeding the oceans with nutrients to increase CO₂ uptake, or pumping aerosols into the atmosphere to reflect sunlight, we could create major new unexpected eco problems.

Geoengineering the climate

http://www.imeche.org/about/keythemes/environment/Climate+Change/Geoeng

For more discussion of renewable energy options and policies, visit Renew.

Posted by Dave Elliott on September 19, 2009 9:54 PM | Permalink