New perspectives on the potential of temperate freshwater wetlands as natural climate solutions based on different CO2 equivalent metrics

Abstract

Abstract There is debate about the use of wetlands as natural climate solutions due to their ability to act as a “double-edge sword” with respect to climate impacts by both sequestering CO2 while emitting significant amounts of CH4. We used CO2-equivalent metrics to assess the net flux of greenhouse gases from wetlands on a comparable basis. Three CO2-equivalent metrics were used to describe the relative radiative impact of CO2 and CH4—the conventional global warming potential (GWP) that looks at pulse GHG emissions over a fixed timeframe, the sustained-flux GWP (SGWP) that looks the sustained GHG emissions over a fixed timeframe, and GWP* that explicitly accounts for changes in the radiative forcing of CH4 over time (initially more potent but then diminishes after a specific period)—against model-derived mean temperature profiles. GWP* most closely estimated the mean temperature profiles associated with net wetland GHG emissions. Using the GWP*, intact wetlands serve as climate solutions. However, restored wetlands only serve as natural climate solutions for mid-century net-zero carbon emission initiatives if effective strategies are implemented to control CH4 fluxes.