Climate Mitigation Potential via Reforestation

Global reforestation, a vital natural-based solution, is expected to provide carbon storage benefits and surface cooling effects targeting climate change. This study integrated a spatially explicit potential tree cover map derived from satellite observations and the advanced Earth System Model CESM2 to evaluate the role of large-scale reforestation in climate change mitigation. Considering the vegetation-climate interactions, this research investigates the patterns, mechanisms, and feedback of reforestation given reforestation effectively alters the carbon cycle, surface energy budget, and water cycle. We estimated that the long-term carbon removal potential of reforestation, considering the impacts of disturbances and albedo, stands at 0.9 PgC year-1. In addition, in exploring the mechanisms underlying reforestation’s temperature effects, we found that changes in vapor pressure deficit, aerodynamic resistance, and albedo have the most profound impacts on spatial temperature change outcomes. We emphasize that the cooling or warming resulting from reforestation is inherently an outcome of complex vegetation-atmosphere feedback occurring under modified microclimate conditions. Last, the study uncovers the interannual variations of reforestation-triggered water cycle changes (i.e. precipitation, soil moisture, and evapotranspiration). By examining the biophysical feedback in reforested lands, we reveal that vegetation in these areas exerts a stronger control over local soil water content via evapotranspiration. In summary, this study underscores the complexity of reforestation as a climate change mitigation strategy with long term carbon sequestration goals. It is emphasized that reforestation is not a universally applicable solution and necessitates strategic, science-based planning, accounting for the interconnectedness of the biosphere, atmosphere, and hydrosphere. Reforestation should complement, not substitute, the pressing requirement for CO2 emissions reduction as part of a comprehensive climate action plan.

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