Gustiness: The driver of glacial dustiness?

During glacial periods of the Late Quaternary, mineral dust emissions from Earth’s dominant source areas were a factor of 2–4 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 consider several possible drivers of glacial–interglacial dust flux changes in an effort to assess their relative importance. 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 find that lake level records near dust source areas do not consistently support the hypothesis that aridity controls glacial–interglacial dust emission changes on a global scale, and we identify evidence negating atmospheric pCO2 and sea level as dominant controls. Glaciogenic sediment supply, vegetation and aridity changes appear to be locally important factors but do not appear to explain the global nature of glacial–interglacial dust flux changes. We suggest that the gustiness hypothesis is aviable explanation for the close correspondence between dust emissions and high-latitude temperatures observed in paleorecords and is worthy of further testing.