We provide the planner's solution to a model where households learn from exogenous natural disaster arrivals about arrival rates and spend to mitigate future damages. Mitigation cannot be decentralized due to positive externalities from curtailing aggregate risks. First-best can be implemented...

In lieu of carbon taxes to address global warming, sustainable investment mandates are proposed to incentivize firms to achieve net-zero emissions. With underspending on mitigation due to externalities, we model the welfare consequences of these investments in firms that qualify by spending...