The Timing of Albedo Declines With Reforestation

Abstract

Reforestation is a leading climate solution for removing carbon dioxide from the atmosphere, but generally decreases surface albedo, which diminishes its climate mitigation value. Knowing how quickly this albedo effect unfolds relative to carbon removal is critical for planning climate mitigation actions, yet the temporal changes in albedo are poorly described. This study uses satellite observations to characterize temporal changes in albedo with stand development for different forest types and ecoclimatic settings around the world. We find that about half of the climate warming effect from decreased albedo occurs within 40 years, but that it takes anywhere from 50 to 120 years to reach 80% of the full effect. The slowest declines occur in extra‐tropical regions and broadleaf forests and woody savannas. The fastest declines occur in tropical environments, and for needleleaf or mixed broadleaf‐needleleaf forests. Results were recast as a global map to help inform reforestation practitioners about the time it takes for reforestation's albedo‐driven warming to approach its maximum effect.