Muted Global Changes Despite Large Regional Responses: The Contrasting Future Trajectories of Inundated and Saturated Wetlands

Wetlands play a crucial role in the global carbon, water, and energy cycles, yet their response to future climate change remains highly uncertain due to varying surface and subsurface hydrological processes. Here, we simulate wetland dynamics using a global land-river coupled model with improved wetland hydrology scheme. Under a high-emission scenario, our model projects 0.8% (-4.7% ~ +6.1%) and 12.3% (-19.5% ~ -6.2%) declines in global annual mean and maximum wetland area, respectively, by 2100. At the regional scale, relative changes can exceed ±50%, with the largest declines over the Amazon and northern high-latitude basins. Saturated wetlands are projected to lose significantly due to groundwater table deepening driven by reduced water availability and thawing of frozen soils. Conversely, global inundated wetlands are projected to expand due to the increased precipitation. These contrasting responses across wetland types, often overlooked in global models, have profound implications for future projections and conservation strategies for mitigating wetland loss and preserving critical ecosystem functions such as carbon storage and biodiversity.