A growing number of environmentalists now celebrate the human power to globally engineer the planet as a technical opportunity to address climate change, and openly condemn the old mantra of limits to growth and sustainability. This fresh dimension to the green perspective and reflection on environmentalism’s failures has been dubbed ‘new environmentalism’. But is the ‘new environmentalist’ imperative of science-based risk management and the optimism of geoengineering a solid basis for a new political manifesto? Does ‘new environmentalism’ signal a humanist turn? Or is it another example of the fashion for politics to borrow on the authority of science to avoid moral contestation? Filmed at the Battle of Ideas this challenging debate is instructive.