Interactions of Dust and Climate
Ina Tegen, Leibniz Institut für Troposphärenforschung (Leibniz Institute for Tropospheric Research)
Micrometer-sized dust particles that are lifted from soils by strong surface winds in arid regions can be carried over thousands of kilometres by wind systems and contribute a large fraction to the global atmospheric particle load. Their effects on the Earth’s radiation balance, biogeochemical processes, and atmospheric chemistry are largely unquantified and remain only partly understood to date. Depending on their size and refractive properties, dust particles influence the incoming solar and outgoing thermal radiation fluxes and atmospheric heating rates. Dust can modify cloud properties and precipitation formation. Another potentially important effect of dust is its influence on oceanic marine microorganisms by supplying nutrients into the ocean surface, overcoming limitations of essential micronutrients like iron. It is also suspected that dust fertilizes some terrestrial ecosystems by depositing micronutrients into soils, and influences atmospheric chemistry due to heterogeneous reactions on the particle surfaces. Emission, atmospheric concentration and deposition of dust are strongly dependent on atmospheric parameters and surface properties, and thus vary considerably on a wide range of timescales. For example measurements of ice cores and marine sediments show that atmospheric dust was considerably enhanced in glacial times compared to modern conditions. This may be directly related to an increased productivity of marine microorganisms. Dust emissions are likely to change in the future in response to anthropogenic changes in climate and consequent changes in natural vegetation patterns and land use. To recognize the role of dust aerosol in a future climate, the process controlling the atmospheric dust distribution as well as their different climate impacts must be understood.
T. D. Jickells, et al.: Global Iron Connections Between Desert Dust, Ocean Biogeochemistry, and Climate. Science 308, 67-71, 2005
Third International Workshop on Mineral Dust 2008: dust2008.tropos.de/