Dust generation and drought patterns in Africa from helium‐4 in a modern Cape Verde coral

Abstract

We show that helium‐4 (4He) concentrations in a modern Porites coral from Cape Verde provides a robust reconstruction of mineral dust loading over the Eastern Tropical Atlantic from mid‐1950's to mid‐1990's. The 4He record demonstrates pronounced increases in dust emission from North Africa associated with the severe droughts in the Sahel. Our record provides direct evidence that dust emission rates in the 1950's, prior to the onset of the Sahel droughts, were a factor of nine lower than during 1980–84. This large change in dust emission rate indicates global aerosol contents would have increased by ∼45% over this period, which may have contributed to a reduction in solar radiation reaching the Earth's surface. We find that dust emission from North Africa is most closely related to drought patterns, rather than to changes in atmospheric circulation patterns resulting from climate oscillations, such as North Atlantic Oscillations and El Nino/Southern Oscillation.