Spaceborne mineral mapping reduces dust’s shortwave radiative impact uncertainty

Abstract

Mineral dust impacts climate through complex interactions with radiation, which remain poorly quantified due to uncertainties in the amount of light-absorbing iron oxides within dust particles. NASA’s EMIT imaging spectrometer, now delivering high-resolution soil mineralogy from the International Space Station, provides the first observational basis to address this gap at a global scale. Using the EMIT data within Earth system model ensembles, we show that surface composition retrievals, especially of iron oxides, reduce uncertainty in the dust shortwave direct radiative effect by over 50% for both present-day and late-21st-century climates. The greatest improvements occur over the Sahara, where the regional dust concentration is high and dust radiative impacts are simulated with improved fidelity. While uncertainties remain, EMIT shifts the primary uncertainty source from mineralogical composition to our imprecise knowledge of the processes controlling the mass concentration of dust particles, especially those related to emission. These findings represent a pivotal step toward mineral-resolved dust aerosol modeling, offering improved insight into how dust alters Earth’s energy balance today and in a warming future.