“A Contrarian Argument for the Expansion of the Coastal Carbon Sink as Regulated by Feedbacks Between Geomorphology and Ecology”

Sea level rise is driving a fundamental reorganization of the coastal zone, in which carbon-rich ecosystems are simultaneously migrating inland, accreting vertically, and eroding towards unvegetated states. In this presentation, I will discuss the geomorphic processes constraining soil carbon accumulation and the ecological processes constraining greenhouse gas emissions that together determine the net radiative forcing of the coastal landscape. Sea level rise creates vertical and lateral accommodation space that enhances soil carbon accumulation in tidal marshes. However, saltwater intrusion also leads to ecosystem transitions that result in loss of existing carbon pools (e.g. forest mortality) and alter methane fluxes (e.g. salinization of freshwater wetlands). Though forecasts of the fate of coastal wetlands are grim, I will argue that ecogeomorphic feedbacks will maintain, and possibly expand, the size of the coastal carbon sink.

Biography:

Dr. Matthew Kirwan is an Associate Professor at the Virginia Institute of Marine Science where he applies principles of geology and ecology to understand the survival of coastal landscapes in the face of sea level rise. His work on coastal carbon cycling earned him a 2017 CAREER award from the National Science Foundation and a 2019 PECASE award from the White House. His work on salt water intrusion into ghost forests has helped inspire a new field of science, and is regularly featured in popular media including the New York Times, USA Today, and the CBS Mornings show. In addition to his academic accolades, Kirwan serves in an advisory role to a number of government and conservation groups engaged in coastal resilience, where he helps review quantitative models, prioritize land acquisition, and assess ecosystem change. Much of his work surrounds the lowlying forests and marshes of the Chesapeake Bay, where Kirwan is a member of the Nause-Waiwash Band of Indians.