Reforestation-induced aerosol cooling effects divergently modulated by various types of biogeophysical feedback

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 (BVOCs) that drive biogenic secondary organic aerosol (BSOA) formation. Using an Earth system model coupled with an advanced aerosol module, we quantify how biogeophysical feedback from vegetation change influences BVOC emissions, BSOA burden and aerosol radiative effects under future land‑use scenarios. Our results reveal that biogeophysical feedback either amplifies or offsets BSOA cooling, depending on regional climate-vegetation interactions. In regions where reduced surface albedo dominates, increasing temperature and BVOC emissions enhance BSOA burden and its radiative cooling. Conversely, in regions where updrafts and cloud formation are enhanced, reduced surface radiation suppresses BVOC emissions and offsets BSOA increases from vegetation changes alone. Globally, these types of feedback 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 non-linearity into the BSOA-climate response. Incorporating such biogeophysical modulation of BSOAs is essential for designing reforestation strategies that maximize climate mitigation benefits.