Lab Seminar: Kyumin Kim

This week, ARE PhD candidate Kyumin Kim presented his ongoing work, entitled "Balancing multiple interventions for dynamically efficient kelp forest restoration under marine heatwave uncertainty."

Kelp forests are declining globally, threatening key socio-ecological functions such as marine refugia, coastal productivity, and community livelihoods. Managers face difficult decisions about when, how, and how intensively to restore such systems under complex feedbacks and uncertainty. In Northern California, recent marine heatwaves (MHWs) and elevated kelp grazing by purple sea urchins have caused severe kelp loss and economic hardship from collapse of the red urchin fishery. Kyumin and his coauthors develop a dynamic bioeconomic model of a kelp-urchin system that is the first to identify welfare-maximizing restoration actions that flexibly depend on the current state of the system. The model integrates (i) kelp-urchin feedback dynamics, (ii) two intensity-varying restoration tools, kelp outplanting and purple urchin removal, (iii) restoration costs and benefits, and (iv) stochastic MHW regimes with uncertain frequency. 

They find contrasting dynamics between restoration tools: outplanting is critical when kelp biomass is low and is scaled back once kelp recovers to moderate levels, while optimal urchin removal is aggressive across most states. Furthermore, they assess the sensitivity of baseline results to alternative natural and social system scenarios. These results are only modestly sensitive to the biological and climate alternatives we consider, scaling in intuitive fashion. In contrast, welfare and policy shift substantially under the social and management alternatives assessed. For example, restricting the functional form of policy response to a commonly used heuristic results in surprisingly high losses of welfare as poor fit to the optimal policy for one action feeds back into the other.