Future trajectories of terrestrial moisture recycling

Roughly half of continental precipitation originates from terrestrial evaporation in upwind regions, yet how these land–atmosphere moisture connections will evolve under climate and land-cover change remains poorly constrained. Earth System Models (ESMs) simulate future precipitation, evaporation, and atmospheric circulation, but they do not explicitly resolve the pathways linking evaporation to downwind precipitation. These pathways can, however, be reconstructed from ESM outputs using moisture tracking.

Here we present different forward- and backward-tracking experiments with the Lagrangian atmospheric moisture tracking model UTrack, forced by multiple CMIP6 ESMs, that quantify future changes in terrestrial moisture recycling across Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) throughout the 21st century. Across models and scenarios, we find an average weakening of terrestrial moisture recycling with warming, with the strongest declines occurring in drying hotspots. In the Amazon rainforest specifically, we find that combined climate change and deforestation may trigger cascading forest transitions mediated by moisture recycling.

We further present results from experiments that investigate whether large-scale ecosystem restoration globally and regionally can counteract specific drying trends through targeted precipitation enhancement.

Our results show that climate change will not only modify precipitation patterns, but will reorganize the continental origins of that precipitation, indicating both future risks for water-stressed ecosystems as well as the potential of ecosystem restoration to mitigate those risks.