Steering the climate system: using inertia to lower the cost of policy: Reply†

Mattauch et al. (2020) claims that the quantitative conclusions in Lemoine and Rudik (2017)—henceforth, LR17—are not robust to using a climate model consistent with recent scientific results. We observe that LR17 in fact analyzes an extension to a more realistic carbon model that generates an efficient emission tax trajectory very similar to that in Mattauch et al. (2020), and we here show that simplifications in the temperature model of LR17 do not qualitatively affect their policy conclusions. Accounting for inertia reduces the initial emission tax by 42 percent and reduces the present value of abatement cost by 39 percent.