Co 2 -altered evapotranspiration moderates future global dryland expansion under climate change

Résumé fourni par la source

Abstract Drylands are highly vulnerable to climate change, yet their recent spatial redistribution and future evolution remain insufficiently understood. Conventional projections often neglect CO 2 effects on potential evapotranspiration (PET), which may yield higher aridity estimates and alter aridity-change hotspot patterns. To address this gap, this study maps the current global distribution of drylands, quantifies historical and future changes in dryland extent, and identifies drying and wetting hotspots under different emission scenarios using a CO 2 -modified PET framework. Using 1994–2023 as the baseline period, global drylands currently occupy approximately 38.58% of the global terrestrial area. From 1960 to 2023, dryland extent showed a fluctuating but overall increasing trend, with an expansion rate of 3.91 × 10 4 km 2 yr −1 . Future projections indicate continued but slower expansion through the 21st century compared with the historical trend. By the end of the 21st century, drylands are projected to cover approximately 40.28% of the global terrestrial area under SSP585. Accounting for rising CO 2 effects moderates projected dryland expansion and alters the spatial pattern of drying and wetting hotspots compared with approaches that neglect CO 2 effects on PET. Regionally, Australia, Brazil, and northern Africa are projected to remain or emerge as persistent drying hotspots, whereas parts of Northwestern China may maintain wetting trends. Parts of Central Australia may undergo a wetting-to-drying hotspot transition, indicating the emergence of new drying hotspots. These findings provide a climate-based indication of regions where dryland risks may be spatially reconfigured. Future dryland risk assessments should further incorporate land-use and water-resource conditions to better evaluate adaptation and management implications.

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