Significant albedo-induced cooling effects across tropical and subtropical dryland biomes

Terrestrial ecosystems can significantly regulate climate through carbon uptake and alterations in surface albedo. However, current climate mitigation assessments largely focus on carbon sinks while overlooking albedo-induced radiative effects. We developed an integrated framework to quantify the net climate effect of global terrestrial ecosystems from 2001 to 2019 by combining net ecosystem productivity with albedo-induced radiative forcing. We estimated the Net Equivalent Carbon Dioxide Stock Change (NESC), which incorporates both Net Cumulative Carbon uptake Equivalent (NCCE) and the Emission Equivalent of Shortwave Forcing (EESF). Results show that global terrestrial ecosystems generated a net cooling effect of 397.52 Gt CO2e during the study period. Among biomes, tropical and subtropical grasslands, savannas and shrublands, and deserts and xeric shrublands, contributed a cooling effect of 95.33 Gt CO2e due to increased albedo, nearly one-quarter of the total NCCE across the 14 biomes, largely driven by declines in photosynthetic vegetation and soil drying in Land use and land cover (LULC) non-conversion areas. These findings provide new perspectives for re-evaluating the climate value of terrestrial ecosystems and a scientific basis for incorporating surface albedo into future nature-based solutions for climate mitigation.