New research from a team of scientists led by Cornell is transforming how researchers understand one of the atmosphere's most abundant and least understood constituents: mineral dust.
Mineral dust, composed of tiny particles lifted from arid regions including the Sahara, Middle East and East Asia, plays a complex role in Earth's climate system. These particles both scatter and absorb radiation, influence cloud formation and even fertilize ecosystems. But until recently, scientists lacked reliable global data on the surface soils' mineral composition, particularly on the prevalence of light-absorbing iron oxides.
Using high-resolution data from a NASA mission aboard the International Space Station, the team has reduced long-standing uncertainty about how airborne dust particles affect Earth's energy balance through interactions with sunlight. The findings published June 1 in the journal Nature Geoscience.
"Dust in the atmosphere can either cool or warm the planet, depending on multiple factors, including what the dust is made of," said Longlei Li, research associate at the Department of Earth and Atmospheric Sciences and at the Cornell Duffield College of Engineering and lead author of the study. "A key focus of this study has been the amount of iron-rich minerals in the dust, mainly iron oxides, because these minerals strongly absorb sunlight."
The study integrates global mineral data from NASA's Earth Surface Mineral Dust Source Investigation (EMIT) into four independent Earth system models. Mounted on the International Space Station, the EMIT instrument uses imaging spectroscopy to map the surface mineral composition of Earth's dry regions at unprecedented resolution. Once scientists know the ground mineral composition in these dry regions, they can predict the composition of the dust that is kicked up into the atmosphere.
The mission has produced the first near-global dataset capable of identifying key dust-forming minerals, including hematite and goethite.
"This study uses space-born remote sensing to tell us at incredibly high resolution - 60 meters - about the surface composition of large, remote desert regions, where travel is difficult or impossible," said Natalie Mahowald, deputy principal investigator on EMIT and the Irving Porter Church Professor in Engineering, and the study's second author. "It was amazing to see how much the quality of the instrument improved our understanding of the mineral composition of these areas."
In a previous study, Li had found that uncertainty in the amount of iron oxides in dust was the single largest obstacle to accurately estimating dust's radiative effects. These minerals strongly absorb solar radiation, meaning even small variations in their abundance could significantly alter whether dust warms or cools the atmosphere.
The new study shows that EMIT data reduces uncertainty tied to iron oxides from 0.62 watts per square meter to just 0.1 watts per square meter - a dramatic improvement by more than a factor of six.
With this data, iron oxides are no longer the dominant source of uncertainty in climate simulations. Instead, other factors - including how dust is emitted, transported and distributed across different particle sizes in the atmosphere - now play a larger role in shaping climate outcomes.
The improvements are most pronounced over the Sahara Desert, the world's largest source of atmospheric dust. There, EMIT-enabled models reduced errors in simulated radiative effects by as much as 80%, bringing them in line with satellite observations of the radiative impact per dust unit.
The study also cuts the uncertainty by more than half across all major global dust source regions, including North Africa and the Middle East.
"This makes our understanding more physically grounded and that's essential for improving climate projections," Li said. "We see clearer regional differences. Dust from parts of North Africa tends to be more iron-rich, which can enhance solar absorption and influence radiative effects toward warming under certain conditions, while dust from some Asian regions is more reflective and cooling."
Globally, dust's overall effect on solar radiation remains within previously estimated ranges. But the new results provide far greater confidence in those estimates.
The study now shifts the focus of dust research. Rather than asking only what dust is made of, scientists can now increasingly concentrate on how dust moves and evolves through the atmosphere and how climate change will alter its sources. The findings also highlight new priorities for research, including better measurements of particle size, improved modeling of dust transport, and expanded observations of mineral composition in under-sampled regions.
Beyond radiation, the work opens doors to understanding dust's broader impacts - from ocean fertilization to snow darkening and cloud formation. As climate models become more precise, such advances are essential for predicting how Earth's energy balance will evolve in a warming world.
The research included co-investigators from the NASA Goddard Institute for Space Studies; the Barcelona Supercomputing Center; the Catalan Institution for Research and Advanced Studies; the Universitat Politècnica de Catalunya - Barcelona Tech; the National Oceanic and Atmospheric Administration Office of Oceanic and Atmospheric Research Geophysical Fluid Dynamics Laboratory; the University of Maryland, Baltimore County; the NASA Jet Propulsion Laboratory; the Planetary Science Institute; the University of California, Los Angeles; and the California Institute of Technology.
Chris Dawson is a communications coordinator for Duffield Engineering.
