Reforestation-induced aerosol cooling effects divergently modulated by various biogeophysical feedbacks

Reforestation and afforestation alter climate not only through biogeophysical processes such as changes in surface albedo, evapotranspiration, and near-surface turbulence, but also by modifying emissions of biogenic volatile organic compounds (BVOC) that drive biogenic secondary organic aerosol (BSOA) formation. Using Earth system model coupled with advanced aerosol module, we quantify how biogeophysical feedbacks from vegetation change influence BVOC emissions, BSOA burden, and aerosol radiative effects under future land‑use scenarios. Our results reveal that biogeophysical feedbacks either amplify or offset BSOA cooling, depending on regional climate-vegetation interactions. In regions where reduced surface albedo dominates, increasing temperature and BVOC emissions enhances BSOA burden and its radiative cooling. Conversely, in regions where updrafts and cloud formation enhanced, reduced surface radiation suppresses BVOC emissions and offsets BSOA increases from vegetation changes alone. Globally, these feedbacks amplify BVOC emission changes in 52% of reforested areas but suppress them elsewhere, intensifying spatial heterogeneity in aerosol climate effects. These divergent feedback pathways introduce strong spatial heterogeneity and nonlinearity into the BSOA-climate response. Incorporating such biogeophysical modulation of BSOA is essential for designing reforestation strategies that maximize climate mitigation benefits.