In 1988 few serious commentators believed that the politics of climate change would be anything other than tortuous. Yet the assumption has remained through the period since that human-induced climate change is an important, urgent and discrete problem which at least in principle lends itself to policy solutions. Optimism has waxed and waned, but the belief has been maintained that at least some forms of policy intervention will yield tangible public benefits. This presumption must now be questioned. Maybe the climate system cannot be managed by humans. This brief survey of climate change over 25 years suggests at least two reasons why. First, there is no ‘plan’, no self-evidently correct way of framing and tackling the phenomenon of climate change which will over-ride different legitimate interests and force convergence of political action. Second, climate science keeps on generating different forms of knowledge about climate—different handles on climate change--which are suggestive of different forms of political and institutional response to climate change. Taken together these two lessons suggest other ways of engaging with the idea of climate change, not as a discrete environmental phenomenon to prevent, control or manage, but as a forceful idea which carries creative potential. This Signature Lecture is co-sponsored by the Balsillie School of International Affairs.