Limited climate change mitigation potential through forestation of the vast dryland regions

Forestation of the vast global drylands has been considered a promising climate change mitigation strategy. However, its actual climatic benefits are uncertain because the forests' reduced albedo can produce large warming effects. Using high-resolution spatial analysis of global drylands, we found 448 million hectares suitable for afforestation. This area's carbon sequestration potential until 2100 is 32.3 billion tons of carbon (Gt C), but 22.6 Gt C of that is required to balance albedo effects. The net carbon equivalent would offset similar to 1% of projected medium-emissions and business-as-usual scenarios over the same period. Focusing forestation only on areas with net cooling effects would use half the area and double the emissions offset. Although such smart forestation is clearly important, its limited climatic benefits reinforce the need to reduce emissions rapidly.

Automated summary

Reforestation in drylands is seen as a promising strategy to mitigate climate change, but its actual benefits are uncertain. Analysis shows that 448 million hectares of land globally are suitable for afforestation, but the albedo effects need to be balanced. The net carbon equivalent can offset around 1% of projected emissions, and focusing on cool regions can further enhance emissions offset. However, the limited climatic benefits highlight the urgency to rapidly reduce emissions.