A Optimal control with pure state constraints

The first section provides additional background on solving control problems with pure state constraints. Section B contains proofs, derivations, and the analysis of the Hotelling-like policy in the main text. Section C describes the numerical example’s calibration and solution. Section D adapts the carbon dioxide (CO2) decay model of Golosov et al. (2014) to our setting and demonstrates that the main text’s primary results still hold. Section E allows business-as-usual emissions to evolve over time. Section F numerically explores different degrees of inertia and the role of the discount rate in the base model. Section G provides a phase portrait analysis of the efficient policy. Section H derives the least-cost trajectory for a geoengineering control.