ARS | Publication request: The Southern Kalahari: A potential new dust source in the southern hemisphere?

Submitted to: Environmental Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 19, 2012
Publication Date: N/A

Interpretive Summary: Most sources of airborne dust in the world are located in the northern hemisphere. Relatively little dust originates from the southern hemisphere and so little dust is deposited in southern oceans. Dust often has iron in it that helps to fertilize the ocean and grow ocean plants that consume atmospheric CO2. Since little dust comes from the southern hemisphere, it limits the amount of iron deposited there to grow plants and consume atmospheric CO2. Since climate and land use can change the sources of dust, this research seeks to determine if new sources of dust may be activated in the southern hemisphere. In this paper, we show that a predicted loss of vegetation may cause new sand dune activity in the southern Kalahari that can promote dust emissions similar to those observed from major contemporary dust sources in the southern Africa region. Our research shows that soil deposits now mostly stabilized by grass vegetation is capable of emitting large amounts of dust from areas between sandy dunes if it begins to blow. Dust from this area is relatively rich in iron that will enhance ocean plant productivity. A study of the routes of air masses from the region show that dust from the Kalahari can commonly reach the Southern Ocean and could enhance the productivity and thus the ability of the ocean to consume atmospheric CO2.

Technical Abstract: Most of the sources of atmospheric dust on Earth are located in the northern hemisphere. The relatively less dust emission in the southern hemisphere in part limits the supply of micronutrients (primarily soluble iron) to the Southern Ocean, thereby constraining its productivity and ability to sequester atmospheric CO2. Climate and land use change can alter the current distribution of dust source regions on Earth. Can new dust sources be activated in the southern hemisphere? Here we show that the predicted vegetation loss and dune remobilization in the southern Kalahari can promote dust emissions comparable to those observed from major contemporary dust sources in the southern Africa region. Dust generation experiments show that in the southern Kalahari, aeolian deposits that are currently mostly stabilized by savanna vegetation are capable of emitting substantial amounts of dust from interdune areas. Dust from the Kalahari is relatively rich in soluble iron, an important micronutrient for ocean productivity. Trajectory analyses show that dust from the Kalahari can commonly reach the Southern Ocean and could therefore enhance its productivity and potentially its ability to sequester atmospheric CO2.