Planning for the worst

Just like blades, phrases can be blunted by overuse. Talk of avoiding "catastrophic climate change" is so familiar, the words no longer instantly stir up apocalyptic images. But in the light of remarks from Defra's chief scientific adviser, it is worth recalling what would be involved. As the Guardian reports today, Professor Bob Watson says Britain must prepare for an increase in temperatures of 4C - a rise deep in catastrophe territory. Even at 3C between a fifth and a half of all species would face extinction. At 4C some human populations could be heading the same way. Swaths of Africa and the Mediterranean would be parched of water and see food production decimated. Over the decades, melting polar ice sheets would increase sea levels to the point where whole island nations - not to mention parts of Britain - would be smothered. The release of CO2 could spiral beyond human control if the heat stopped natural forest fires from burning themselves out. In the darkest scenario, civilisation would be on the slipway to oblivion.

Mercifully, that is far from certain - but with warming in excess of 2C very little is. Is Prof Watson encouraging fatalistic acceptance of it? Emphatically not. His responsibilities include advising not just on climate policy, but also flood defences. And the only responsible way to plan coastal barriers is on the basis of an honest appraisal of what the future could bring - however depressing that may be. In line with the Stern report and the IPCC, Prof Watson believes all governments should seek to contain global warming to 2C. He merely acknowledges that the chance that this target will not be met is too real to be ignored.

That is putting it mildly. Even if global emissions could be stabilised at current levels, a rise in excess of 2C would be a substantial possibility. Indeed it might become a probability if China and India follow the west and clean up their industry to tackle acid rain. (The sulphurous gases which cause that problem also offset global warming by reflecting sunlight.) Instead of stabilising, however, emissions continue to rise, and the political obstacles on turning the tide remain formidable. The passing of George W Bush next year will remove only one of several. The US is now so far above Kyoto baselines, that even when a more constructive president takes over - as either candidate would prove - they may demand a deal that takes account of this catastrophic starting point. But other countries who have been working to cut emissions might resist this as a reward for failure. There will be other sticking points, too. China is now the world's biggest emitter, so no meaningful deal can exclude it. But there is scope for argument about whether galloping emissions from the workshop of the world are the responsibility of the Chinese producers or the western consumers they serve. A recent report by the Stockholm Environment Institute has underlined this point.

The Stern report established that - from the point of view of the global economy - prevention is cheaper than cure. For individual countries, however, who consider the calculus in isolation, the balance will often be reversed. After all, even with a sizable economy such as Britain, whatever sacrifices are made to cut emissions the direct effect on the global emissions - and thus the climate - will be marginal, and self-interest starts to dictate a strategy of mitigating catastrophe instead.

Prof Watson acknowledges this miserable - yet hard - logic by suggesting preparations be set in train for a rise of up to 4C. But he rightly argues that rich countries can still recast the logic through coordinated action. A joint agreement to find a way of making carbon capture work, and to fund it, would be a first step. Every country could argue that the vast funds involved are unaffordable. Each, however, is one part of the same planet - and it can no longer afford delay.

(Editorial, The Guardian, 07/08/2008)