Drylands and Global Dust Transport

Deserts are not merely passive, isolated regions of aridity; they are the dominant source of the mineral dust that circulates through Earth's atmosphere, with the Sahara alone estimated to emit several hundred million tonnes of dust into the air each year, making it by far the single largest dust source on the planet. NASA's CALIPSO satellite, using a laser-based instrument called a lidar to profile atmospheric particles in three dimensions, identified the Bodélé Depression in northern Chad, a dried former lakebed rich in diatomite, fossilized remains of microscopic aquatic algae, as the single most productive dust source within the Sahara, responsible for a disproportionate share of the dust that subsequently crosses the Atlantic Ocean.