Researchers have mapped billions of trees across the African Sahel, a milestone reported by the University of Copenhagen’s press service. Over the past decades, scientists have observed a warming trend linked to human activity. The primary culprit is carbon dioxide, which traps heat in the atmosphere through the greenhouse effect. The main strategy to counteract this warming centers on cutting emissions from industry. As a practical compromise, many advocates also support tree planting to offset carbon emissions.
To monitor the effectiveness of these approaches, researchers from the University of Copenhagen collaborated with NASA to develop a method for counting trees in vast areas and estimating the amount of carbon stored in each one. This breakthrough makes it possible to gauge both the tree population and the environmental impact of forests on a large scale.
The project relied on a database containing 300,000 ultra-high-resolution satellite images of the Sahel. These photographs were stitched together into a single mosaic that provides a top-down view of the landscape. An artificial intelligence system, powered by NASA’s supercomputing resources, was trained to recognize individual trees. By learning features such as the distinctive flat canopies of acacias, the algorithm could identify trees with precision and distinguish them from surrounding land.
The outcome of this work is striking. The arid Sahel region holds roughly 10 billion trees. These trees collectively sequester about 840 million tons of carbon, highlighting the significant role forests play in the global carbon cycle and the potential impact of large-scale reforestation efforts on climate mitigation.