Today’s financial crisis has been heralded as the worst since the 1930s, although governments have taken emergency action to try to stave off similarly dire consequences. Even if they succeed, the world’s economies are suffering, and several have already entered recession.

But even a severe recession would be small compared with what is likely to result from climate change if greenhouse gas emissions are left unchecked. Global warming has the power to plunge the world into a crisis deeper and more permanent than the Great Depression and two world wars of the last century, according to Lord Nicholas Stern, author of an influential study for the UK Treasury on the economics of climate change.