Diminished biophysical cooling benefits of global forestation under rising atmospheric CO<sub>2</sub>.

Kan, Fei; Xu, Hao; Tang, Shuchang; Peñuelas, Josep; Lian, Xu; Roebroek, Caspar T J; Anniwaer, Nazhakaiti; Wang, Kai et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

Forestation is a proposed solution for mitigating global warming through carbon sequestration. However, its biophysical effects through surface energy modulation, particularly under rising CO<sub>2</sub> levels, is less understood. Here we investigate the biophysical effects of global potential forestation on near-surface air temperature (T<sub>a</sub>) under increasing CO<sub>2</sub> concentrations using a land-atmosphere coupled model with slab ocean module. Our findings reveal that, under current climate conditions, the biophysical effect of global full-potential forestation can reduce land surface T<sub>a</sub> by 0.062 °C globally. However, this cooling benefit diminishes as CO<sub>2</sub> rises. While elevated CO<sub>2</sub> slightly alters evaporative local cooling via stomatal closure and adjustments in forestation-driven rainfall regimes, the dominant reduction stems from non-local mechanisms. Background climate shifts reorganize forestation-induced horizontal temperature advection, weakening remote cooling in the Northern Hemisphere. These findings highlight the necessity of incorporating dynamic forest management strategies to optimize mitigation potential under a changing climate.