What will have been the world's most important resource

Speaking on the record at a recent Chatham House conference on The Politics of Climate Change Agreement, Hans Schellnhuber, the Head of PIK - the Potsdam Climate Institute - presented two very striking graphics based on recent and fully-attested science. The first showed that, whereas the target of a 2 °C average global warming may have originally been adopted for the political convenience of having a target, it now has to be regarded as the absolute upper limit of warming if we are not to be on the receiving end of hugely disruptive climate impacts - and even then the odds of avoiding such impacts are not ones we'd accept going into an operating theatre or crossing a road unless all we hold dear depended on getting to the other side. He followed that with a slide based on our remaining carbon 'budget' - the amount of greenhouse gases (in carbon-equivalent terms) that we can globally afford to emit without going above that warming limit - derived from very robust research published in Nature in April. What the slide showed was how drastically global emissions would have to decline depending on the year in which they peak, keeping the carbon budget - the area under each of the lines on his graph - constant. And what it presented was pretty much a political impossibility theorem. If emissions peak next year, 2010, then they'll have to decline by 2% pa until 2050 ending up at half the global level in 1990; if they start to decline from 2020, they'll have to come down by 6% a year, more than Kyoto was intended - but has woefully failed - to deliver. And if we wait till 2030, they will have to drop by an astonishing 23% pa, and by 2040 we will have to be in 'negative emissions' territory - sequestering more ghgs than we emit. The further out the peak year, the more politically realistic that emissions might begin to decline then, but the more inconceivable the necessary rate of reduction.