Assessing changes in global terrestrial live biomass over the 21st century
Ecosystems on land store large amounts of the carbon emitted by human activities, and protecting and restoring forests and other vegetation are important tools in slowing climate change. However, there are large uncertainties in global estimates of the balance between how much carbon ecosystems store and how much they release into the atmosphere due to deforestation, wildfire, and other disturbances. To improve estimates of the global carbon balance, NASA, USDA-FS, and other contributors assessed changes in the amount of carbon stored by live woody vegetation (such as trees and shrubs) globally over the course of the 21st century (Xu et al, 2021). The researchers used a combination of national forest inventories, remote sensing, and machine learning to reduce uncertainties and provide improved annual estimates of carbon emission and removal. They estimate that plants uptake 4.9 to 5.5 petagrams of carbon (PgC) each year, more than offsetting annual losses to disturbance that total 4.5 to 4.7 PgC annually and leaving a net of 0.23 to 0.88 PgC captured each year. For reference, fossil fuel emissions are between 6.9 and 10.0 PgC per year.