Accounting for albedo change to identify climate-positive tree cover restoration

Abstract

Restoring tree cover changes albedo, which is the fraction of sunlight reflected from the Earth’s surface. In most locations, these changes in albedo offset or even negate the carbon removal benefits with the latter leading to global warming. Previous efforts to quantify the global climate mitigation benefit of restoring tree cover have not accounted robustly for albedo given a lack of spatially explicit data. Here we produce maps that show that carbon-only estimates may be up to 81% too high. While dryland and boreal settings have especially severe albedo offsets, it is possible to find places that provide net-positive climate mitigation benefits in all biomes. We further find that on-the-ground projects are concentrated in these more climate-positive locations, but that the majority still face at least a 20% albedo offset. Thus, strategically deploying restoration of tree cover for maximum climate benefit requires accounting for albedo change and we provide the tools to do so.

Spatial heterogeneity in climate change effects across Brazilian biomes

“…Forests typically have a lower albedo compared to other land covers, meaning they absorb more sunlight. However, when forests are cleared and replaced with agricultural land or urban areas, the albedo of the land increases, causing it to reflect more sunlight back into space 75 . While this may initially appear to have a cooling effect on the Earth’s surface, it is outweighed by the loss of forests’ ability to sequester carbon dioxide, resulting in an overall warming effect on global temperatures.…”