Quantifying CDR through afforestation and reforestation (A/R) is essential for assessing its contribution to climate change mitigation and for evaluating the effectiveness of A/R projects. However, accurately quantifying CDR remains challenging for several reasons:
-
Forest growth resulting from A/R must be distinguished from other drivers of biomass accumulation, such as recovery following natural disturbances, regrowth after wood harvest, and regrowth in shifting cultivation cycle.
-
Annual carbon uptake in biomass and soils of growing forests varies substantially across forest types, biomes, and geographical locations.
-
Natural disturbances (e.g., fires, windthrow, insect outbreaks) and anthropogenic disturbances (e.g., harvest and human-caused fires) can reverse carbon gains by releasing carbon previously stored in afforested and reforested areas.
Models, national greenhouse gas inventories, and Earth observation–based approaches are all used to estimate global CDR from A/R. The key challenge is to determine how these complementary data sources can be combined to produce the most robust, reliable, and accurate estimates of CDR from A/R.