Analysis of coastal wetland geography and policy in Humboldt Bay: adapting wetland policies for a changing climate

Humboldt Bay has lost 90% of its tidal salt marsh and an unknown amount of freshwater marsh due to human impacts over the past two centuries. Sea level rise due to climate change has the potential to cause even greater loss of coastal wetlands. This project sought to model the potential loss of tidal salt marsh around Humboldt Bay due to sea level rise and, in light of sea level rise, examine the difficulties in the permitting, planning and implementation processes of wetland projects. Tidal salt marsh migration potential was modeled using MaxEnt, a habitat suitability modeling package. Wetland policies were analyzed qualitatively through document data and interviews with regional actors. The salt marsh migration potential model predicted that with one meter of sea level rise the acreage of land capable of supporting salt marsh could increase slightly, but with two meters of sea level rise the acreage of land capable of supporting salt marsh could decrease by over half under a best-case scenario. The policy analysis found that risk aversion played a large role in causing timeline and cost increases for wetland projects, causing some projects to fail, and that the No Net Loss of Wetlands policy may not be adequate for a changing climate.