At the heart of policy debates about our collective responses to climate change is the issue of risk and uncertainty - ‘unknown unknowns’ about the impact of global warming. In this Vox Talk, Gernot Wagner - co-author with Harvard’s Martin L. Weitzman of 'Climate Shock: The Economic Consequences of a Hotter Planet’ - argues for Pigovian taxes and carbon pricing, against geoengineering solutions, and why 'we need to stick it to CO2, not to capitalism’.