There is nothing the environmental movement likes better than a highly polarising row that becomes increasingly vitriolic, generates more heat than light, and then culminates in self-harming deadlock.
Thankfully, as if we weren't lucky enough with the opportunities that nuclear power, GM crops and international climate negotiations provide us to bite chunks out of each other, another row is emerging that promises to leave all other green-on-green arguments in the shade. Ladies and gentlemen, I give you geo-engineering.
The news today that the Guardian has obtained leaked documents showing that the IPCC will move ahead with proposals for further research into geo-engineering techniques that could culminate in field trials will inevitably spark fresh conflict between those climate scientists who think tinkering with the climate represents the last best chance of avoiding catastrophe, and those environmentalists who fear the cure could prove worse than the disease.
Green groups are already mobilising opposition to the plans, arguing – quite rightly – that geo-engineering could have catastrophic unintended consequences for the atmosphere, will throw up huge geo-political governance challenges, and distracts from the urgent task of cutting greenhouse gas emissions.
As they warned in an open letter to head of the IPCC, Rajendra Pachauri: "Asking a group of geo-engineering scientists if more research should be done is like asking bears if they would like honey."
The scientists counter that the reason for further research is to minimise the risk of unintended consequences, that we've spent decades trying to cut emissions and got nowhere, and that the latest climate change projections for this century are now so severe it is only prudent to look at alternatives. They are largely silent on the crucial issue of global governance for these projects, but then again the questions that need answering on that front are well beyond their pay grade.
The problem is that, as with nuclear and GM, the immediate framing of the geo-engineering debate between two polarised camps means all nuance is lost, leaving potentially effective technologies tarred with the same brush as those that really should be avoided at all costs.
Taking its broadest definition, geo-engineering means simply anything that can influence the climate on a large scale. As such, man-made greenhouse gas emissions are themselves a form of geo-engineering, a fact which – depending on how you look at it – either lends weight to environmentalists' calls for a moratorium on all geo-engineering projects, or indicates how naïve they are to suggest there should be no more geo-engineering.
More specifically, the range of technologies that have been classified as geo-engineering are so broad that neither blanket support nor blanket opposition can be justified.
I have heard afforestation projects described as 'geo-engineering', which is technically correct given the impact they can have on carbon concentrations in the atmosphere. I'm guessing those green groups criticising investment in geo-engineering research do not mean research into the effectiveness of forest carbon sinks, although they do probably mean research into genetically modified trees capable of soaking up greater levels of carbon dioxide.
Similarly, it is hard to imagine anyone objecting to proposals to paint buildings and urban streets white as a means of tackling urban hot-spots. It may be described in some quarters as geo-engineering, but this cost-effective technique of lowering local temperatures has been demonstrated for centuries in hot countries, has been shown to reduce energy use and, if scientists are to be believed, could have a positive global climate impact if widely adopted.
Other proposals are more controversial, but should not be dismissed out of hand. Cloud seeding is already a well-established phenomenon, and proposals to orchestrate increases in reflective ocean cloud cover by spraying water into the air have the huge advantage of being quickly reversible if unintended consequences result.
These temperature-controlling concepts may not tackle the grossly under-reported ocean acidification that has resulted from increased atmospheric concentrations of carbon dioxide, but they are still worth exploring.
Meanwhile, burying charcoal or capturing carbon using artificial trees should only prove as controversial as the carbon capture and storage projects that are already being pursued (which in fairness are still pretty controversial). Along similar lines, there is no argument against genetically modifying crops to make them lighter and more reflective beyond those already levelled against GM crops in general.
In contrast, any proposals that suggest messing with the chemical content of the oceans or pumping sulphates into the atmosphere appear far too risky to countenance. It is easy to envisage a scenario where such experiments spiral out of control, damaging marine habitats or disrupting global weather patterns – and that is before you even begin to address the question of who should control these projects.
Equally, those suggesting using giant space mirrors to reflect the sun's rays back into space should quit daydreaming and return to reading their James Bond novels.
My point is that there is a hierarchy of feasibility governing geo-engineering projects, ranging from those that make good sense and should be pursued immediately, through those that may prove valuable in the medium term, to those that should not be touched with the proverbial barge pole.
Green groups are right to counsel caution, right to warn that geo-engineering projects will require robust governance, and right to warn that they could distract from the far more urgent need to curb greenhouse gas emissions. But this is not a black-and-white issue; as such, well-funded research into some of the potentially less dangerous geo-engineering techniques has to continue free from constant calls for a blanket ban.
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