Diverse crowds of NGO demonstrators lend passion and colour to the UN climate change negotiations held in November or December each year. I vividly recall a session in Montreal in an icy December. On our way to the conference venue, we were greeted by impassioned demonstrators, standing in deep snow, holding aloft banners demanding an “end to global warming”. These men and women might have been forgiven for taking a more benign view of a phenomenon that might actually make their native habitat a more hospitable place in deep winter but their devotion to a universal cause was undimmed by