Speaker: David McGee, Columbia University. Abstract: During glacial periods of the Late Quaternary, mineral dust emissions from Earth's dominant source areas were a factor of two to four higher than interglacial levels. The causes of these fluctuations are poorly understood, limiting interpretation of dust flux records and assessment of dust's role in past climate changes. Here we demonstrate that a wide range of data supports wind gustiness as a primary driver of global dust levels, with steepened meridional temperature gradients during glacial periods causing increases in dust emissions through increases in the intensity and frequency of high-speed wind events in dust source areas. We also test the importance of other proposed drivers, finding that lake level records near dust source areas are inconsistent with the hypothesis that aridity controls glacial-interglacial dust emission changes and identifying evidence negating atmospheric pCO2, sea level and sediment supply as dominant controls. We suggest that the gustiness hypothesis is a viable explanation for the close correspondence between high-latitude temperatures and dust emissions in remote source areas and is worthy of further testing.

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