Key takeaways
- UCLA research shows that desert dust in the atmosphere has dropped about 10% since 2003.
- The dust has a slight cooling effect on the planet, and recent decreases may have played some role in hastening global warming.
- Scientists are continuing to investigate why atmospheric desert dust is declining.
Atmospheric desert dust has long swirled around the globe, but a new UCLA study presents the strongest evidence yet that global dust is mysteriously decreasing.
Because atmospheric dust overall has a slight cooling effect on the climate, the researchers say its decrease may have contributed modestly to recent climate warming.
The study, which combined satellite observations, ground-based measurements and atmospheric models, found that the amount of dust in Earth's atmosphere decreased by about 10% from 2003 to 2023.
Most of the atmospheric dust originates in the Northern Hemisphere, with major desert regions such as the Sahara in North Africa and the deserts of Asia, including the Gobi, contributing much of the global dust burden.
The causes of the recent decline, however, remain unclear, according to the study, published today in the journal Science Advances.
"This is the strongest evidence to date that Earth's atmosphere became less dusty in the early 21st century," said lead author Ashok Gupta, who conducted much of the analysis as a researcher and assistant project scientist in the UCLA Department of Atmospheric and Oceanic Sciences. He is now a staff scientist at Vanderbilt University.
Study co-author Jasper Kok, a UCLA atmospheric scientist and principal investigator on the project, noted that the recent dust decrease marks a change from much of the 20th century, during which atmospheric dust increased before peaking in the 1980s for reasons scientists are still exploring.
"Because of atmospheric dust's slight overall cooling effect on the climate, the decline in dust that we're seeing now likely contributed modestly to the warming seen from human-caused climate change," Kok said.
"The decline in dust has other potential effects on ecosystems, air quality and the atmosphere," Kok said. "Dust circulating through the atmosphere plays an important role in depositing nutrients and minerals into oceans and on land. It also contributes to air pollution and decreases the reflectivity of snow and ice."
Even with the decline since the 1980s, dust levels are still elevated compared to pre-industrial times, Kok noted. In addition to deserts like the Sahara and the Gobi, some of the dust today comes from drying lakebeds where agriculture and other needs led humans to reroute water, such as at the Salton Sea and Owens Valley in California, Utah's Great Salt Lake and the Aral Sea on the border of Kazakhstan and Uzbekistan, he said.
Gupta is now investigating what is driving the decline in atmospheric dust through ongoing research at Vanderbilt, in collaboration with UCLA.
"We are working to determine how much of the global dust decline can be attributed to changing surface winds and other environmental factors and what those changes could mean for atmospheric dust in a future climate," Gupta said.
