By Sofie Bates,
NASA’s Goddard Space Flight Center
Using commercial, high-resolution satellite images and artificial intelligence, an international team including NASA scientists mapped almost 10 billion individual trees in Africa’s drylands in order to assess the amount of carbon stored outside of the continent’s dense tropical forests. The result is the first comprehensive estimate of tree carbon density in the Saharan, Sahel, and Sudanian zones of Africa. The team reported its findings March 1 in Nature, and the data are free and publicly available.
The researchers found there are far more trees spread across semi-arid regions of Africa than previously thought, but that they also store less carbon than some models have predicted. In the new study, the team estimated roughly 0.84 petagrams of carbon are locked up in African drylands; a petagram is 1 billion metric tons.
Having an accurate tree carbon estimate is essential for climate change projections, which are influenced by how long trees and other vegetation store carbon. This “carbon residence time,” as scientists call it, is very short for grasses and bushes, which grow seasonally, but much longer for trees that grow for years. Knowing how much carbon a landscape stores is dependent on knowing exactly what is growing there.
Beyond the vast tropical forests spread across the middle of the continent, African landscapes range from dry grasslands wit …