NATURAL WETLANDS: CHARACTERIZING VEGETATION AND GLOBAL INUNDATION DYNAMICS FOR METHANE MODELING

Natural wetlands are the world's largest source of methane to the atmosphere. Boreal wetlands, dominated by flooded and non-flooded peatlands, account for ~50% of global wetland area and ~30% of wetland methane emission. Tropical wetlands, composed primarily of forests inundated via riverine flooding, account for ~40% of the world's wetland area and two-thirds of emissions. Understanding climate-sensitive processes prevailing in the world's natural wetlands is crucial to understanding and predicting their biogeochemical responses to interannual and longer-term climate variations. The wide spectrum of vegetation, hydrological regime, soils, and seasonality means that no single system describing local and regional wetland environments encompasses their global diversity particularly with regard to methane-relevant information. This undermines efforts to characterize and model wetlands and their methane emissions under current and future climates. In addition, application of methane models historically required externally-defined wetland data sets due to the continued challenge of modeling the distribution of wetlands themselves.

We report on the integration of monthly, decadal satellite-derived data on inundation seasonality and extent with a global wetland data set characterizing vegetation and other methane-relevant environmental information. We report results in the framework of a newly-developed, methane-centric wetland-classification system jointly applicable to wetland distributions and to wetland sites represented in the methane-flux literature. We propose applications of the new satellite-augmented data set to modeling methane emissions, and to guiding the development of models of wetland distribution.