The main sources of atmospheric dust on Earth are located in drylands and at present, most of the active dust sources are in the northern hemisphere, which accounts for more than 90% of global dust emissions. Although, currently, the contribution of dust emission from the southern hemisphere is relatively low, reductions in vegetation cover due to land use or climate change provide the potential for new source areas to emerge. The Kalahari Desert is a potentially large dust source in the Southern Hemisphere, which is prone to remobilization in response to possible losses of vegetation cover. Reactivation of the Kalahari dunes and subsequent emission of dust has the potential to cause considerable changes to the atmospheric composition and biogeochemical cycling of the Southern Hemisphere. Quite surprisingly, the impact of dune activation on the regime of dust emissions from the Southern Kalahari landscape has never been investigated before. Moreover, it is not clear whether reactivated dunes could support the same biomass as the ecosystem in its stable state. The objective of the proposed research is to investigate the response of the Kalahari environment to changing climate and land use. It will assess changes in land cover and dust emissions resulting from the predicted aridification of interior southern Africa, large scale encroachment of woody plants, and increasing population and demand for animal products from this region dominated by pastoral land use.
This study will shed light on the large scale implications of climate change and overgrazing in one of the most vulnerable arid landscapes in the southern hemisphere. Through a variety of field measurements both in degraded and well managed grazing lands in Botswana, it will provide an integrated assessment of the natural and human threats faced by the Kalahari environment and its people, and allow for an evaluation of the sustainability of different land use strategies. These assessments will provide critical information for land users and managers in other environmentally sensitive arid regions. Beyond the regional impacts in Africa, this research will provide a quantitative assessment of the potential dust emissions from the Kalahari, which may considerably alter the composition and biogeochemistry of the atmosphere of the Southern Hemisphere. Because of the crosscutting nature of this work, it is supported by NSF?s programs in Geomorphology and Land-use Dynamics, Geography and Spatial Sciences, Earth Science Instrumentation and Facilities, and Office of International Science and Education.
