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Smaller desert dust cooling effect estimated from analysis of dust size and abundance


Desert dust aerosols affect Earth’s global energy balance through direct interactions with radiation, and through indirect interactions with clouds and ecosystems. But the magnitudes of these effects are so uncertain that it remains unclear whether atmospheric dust has a net warming or cooling effect on global climate. Consequently, it is still uncertain whether large changes in atmospheric dust loading over the past century have slowed or accelerated anthropogenic climate change, or what the effects of potential future changes in dust loading will be. Here we present an analysis of the size and abundance of dust aerosols to constrain the direct radiative effect of dust. Using observational data on dust abundance, in situ measurements of dust optical properties and size distribution, and climate and atmospheric chemical transport model simulations of dust lifetime, we find that the dust found in the atmosphere is substantially coarser than represented in current global climate models. As coarse dust warms the climate, the global dust direct radiative effect is likely to be less cooling than the −0.4 W m−2 estimated by models in a current global aerosol model ensemble. Instead, we constrain the dust direct radiative effect to a range between −0.48 and +0.20 W m−2, which includes the possibility that dust causes a net warming of the planet.

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Figure 1: New constraints on dust properties and prevalence.
Figure 2: Size-resolved global loading of desert dust aerosols.
Figure 3: Global emission rate and atmospheric loading of desert dust aerosols.
Figure 4: Constraints on the global direct radiative effect (DRE) of PM20 dust.


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We thank V. Bouchard, B. Yi, K.-N. Liou, P. Yang, A. Tripati, D. Neelin, J. Bortnik, R. Martin, K. Ledger, A. Evan, S. Shaked and R. Kahn for helpful comments and discussions, and thank P. Rosenberg for providing the data from ref. 37. We acknowledge support from National Science Foundation (NSF) grant 1552519 (J.F.K.), NASA grants NN14AP38G (D.A.R. and C.L.H.) and NNG14HH42I (R.L.M.), and from the US Department of Energy as part of the Regional & Global Climate Modeling program (C.Z.).

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J.F.K. conceived the project, designed the study, performed the analysis, and wrote the paper. D.A.R., C.Z., C.L.H., R.L.M., D.S.W., S.A. and K.H. contributed global model simulations. Q.Z. assisted with designing the statistical model to constrain dust properties from different data sets. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Jasper F. Kok.

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The authors declare no competing financial interests.

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Kok, J., Ridley, D., Zhou, Q. et al. Smaller desert dust cooling effect estimated from analysis of dust size and abundance. Nature Geosci 10, 274–278 (2017).

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