If we’re going to get to net zero in time, economists argue that carbon taxation alone is the best policy. But less than a quarter of emissions are subject to any carbon pricing. And even then, the price of carbon is far too low. So how much climate finance will it take to fill that gap to get us to a socially optimal solution? Lasse Heje Pedersen talks to Alissa and Tim about how he estimates the rate of exchange between the cost of capital and a carbon tax, and what that implies for policy.