The field of environmental economics in general — and climate economics in particular — is exploding. And the guest on episode 44 of Forecast, Solomon Hsiang from UC Berkeley, who co-directs the Impact Lab, is helping to crack open some of the recalcitrant oyster shells of the field. How does climate influence conflict, migration and economic productivity? We talk through some of the big challenges in addressing these topics: the frequent impossibility of running experiments and the accompanying use of quasi-experiments; the growing use of — at last! — data; how incredibly hard it is to disentangle the influence of single factors — like climate — in a complicated human system. In many ways economics is decades behind physical sciences. As Sol explains, we’ve now for the most part forgotten about the initial debates regarding fluid dynamics, but economics is still very much at the phase of figuring out elementary processes. Sometimes this means that the major findings reside in statistical approaches, without clear mechanistic understanding. But Sol and his colleagues are working towards linking microscale human decisions to aggregate societal processes, and it is this sort of understanding that will, and indeed already is, proving important in a policy context.