One, two, tree: how AI helped find millions of trees in the Sahara

Efforts to map the Earth's trees are growing - and could change our understanding of the planet's health

When a team of international scientists set out to count every tree in a large swathe of west Africa using AI, satellite images and one of the world's most powerful supercomputers, their expectations were modest. Previously, the area had registered as having little or no tree cover.

The biggest surprise, says Martin Brandt, assistant professor of geography at the University of Copenhagen, is that the part of the Sahara that the study covered, roughly 10%, where no one would expect to find many trees", actually had quite a few hundred million".