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Climate and dust

Climate and dust

Dust is an airborne suspension of very fine mineral particles derived primarily from surface soils or injected into the atmosphere during volcanic eruptions. Particles are initially generated from weathering, geomorphic processes, and from explosive volcanism. Dust is an important constituent of tropospheric aerosol, which consists of a mixture of sulphate aerosol, black carbon and organic carbon, nitrate and mixed particles such as sea salt and mineral dust. Dust, and the other components of tropospheric aerosol, affect climate in a variety of ways; this impact is measured in terms of changes in radiative forcing, i.e. the implied perturbation of the Earth’s energy budget caused by changes in the aerosol budget.

Mineral dust can change radiative forcing through direct effects, in which dust particles interact with solar energy and both scatter and absorb radiation, and indirect effects on cloud formation and physical properties, and precipitation. There remains considerable uncertainty in both the sign and the magnitude of dust radiative forcing: estimates of the net direct radiative forcing by dust under current climate, based on dust-cycle model simulations, range from -0.56 to +0.1 W m-2. This largely results from simplified assumptions about dust characteristics, such as particle size, shape and mineralogical mixing. There is an urgent need to better understand how dust impacts climate to refine model simulations of present, past and future climates.

Image as described adjacent

Dust storm in the Middle Son River valley, India, 7 April 2009

Research Associate Dr Adam Durant was a Marie Curie Experienced Researcher between 2007-2008 as part of the GREENCYCLES Research Training Network. To address uncertainties related to direct forcing of climate by desert dust, Dr Durant carried out numerical modelling to place quantitative constraints on the sensitivity of calculated optical parameters (extinction coefficient, asymmetry parameter and single scattering albedo) to the physical and compositional properties of mineral dust aerosol. Uncertainty in the magnitude of global average dust direct forcing from variability in dust particle size and mineralogy is currently being investigated in collaboration with colleagues at Institut Pierre Simon Laplace (CNRS), France, using the general circulation model LMDZ4 (Laboratoire de Météorologie Dynamique with Zoom capability).

For more information on the climatic effects of dust, please see:

  • Durant, A. J., S. P. Harrison, I. M. Watson and Y. Balkanski (2009), Sensitivity of direct radiative forcing by mineral dust to particle characteristics, Prog. Phys. Geog., 33, 80-102. doi:10.1177/0309133309105034