Assessing Wetland Methane Emission Changes in the Conterminous U.S. from 1973 to 2010

Abstract:

Climate and human land use are the main drivers of terrestrial ecosystem methane (CH₄) emissions. Wetland expansion and contraction, methane production and release, as well as the interactions of methane with the carbon cycle, are processes critical to the examination of climate change mitigation strategies. This study uses the parallel Integrated Biosphere Simulator (pIBIS) and the State-and-Transition Simulation Model (ST-Sim) to simulate the climate-driven and land-use-driven CH₄ emissions in the U.S. from 1973 to 2010. The ST-Sim model is used to backcast annual historical wetland cover from 2010 to 1973 based on recent baseline wetland maps (i.e. National Land Cover Dataset and National Wetland Inventory), historical land cover change trends, and probabilistic spatial multipliers. The pIBIS model is used to simulate the change of wetland water table depth and the production, oxidation, and transportation processes of CH₄. Simulations are performed at 1-km spatial resolution using Department of Energy super-computing resources. Post-simulation programs are developed to analyze the spatial distribution and temporal trends of CH₄ emissions in relation to inter-annual wetland area variation and climate (rainfall and temperature) variation. Relationships between CH₄ emission and carbon sequestration and CO₂ emission are also analyzed.

Keywords: climate change, land cover change, land use change, greenhouse gas, biogeochemical model