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Earth system models (ESMs) are essential tools to understand climate change impacts on wetlands. However, current ESMs usually represent wetland hydrology in oversimplified ways, resulting in low confidence of their projection of wetland evolution.

In a published in Nature Communications, researchers from Pacific Northwest National Laboratory (PNNL), Lawrence Berkeley National Laboratory, and the University of Michigan focused on improving the simulation of inundated wetlands using a state-of-the-science ESM that includes physical mechanisms of inundation and a range of climate scenarios to project changes and predict factors that can control wetland dynamics.

The refined model simulates the wetlands and validates against satellite observations. With the refined model, researchers further found the wetlands over North America will be significantly affected by climate change under future scenarios.

The results reveal projected changes in wetland characteristics over North America from 25° to 53° North under two climate scenarios using a state-of-the-science ESM. At the continental scale, annual wetland area decreases by ~10% (6%–14%) under the high emission scenario, but spatiotemporal changes vary, reaching up to ±50%.

As the dominant driver of these changes shifts from precipitation to temperature in the higher emission scenario, wetlands undergo substantial drying during the summer season when biotic processes peak. The projected disruptions to wetland seasonality cycles imply further impacts on biodiversity in major wetland habitats of the upper Mississippi, Southeast Canada, and the Everglades.

Furthermore, wetlands are projected to significantly shrink in cold regions due to increased infiltration as warmer temperatures reduce soil ice. The large dependence of the projections on climate change scenarios underscores the importance of emission mitigation to sustaining wetland ecosystems in the future.