A 10,000-YEAR RECORD OF DUNE ACTIVITY, DUST STORMS, AND DROUGHT IN THE CENTRAL GREAT PLAINS

Drought in central North America can have severe economic and environmental impacts, but its causal mechanisms remain poorly understood, in part because of the short observational record. Here we present a 10000-year reconstruction of dune activity and dust production in the central Great Plains region, based primarily on optically stimulated luminescence (OSL) ages from dune sand and loess (dust deposits). Clusters of OSL ages indicate periods of eolian activity triggered by dry periods more severe and/or longer-lasting than any historical drought. This record provides a long-term perspective on hypotheses linking Great Plains drought to anomalous sea surface temperatures (SST) in the tropical oceans (cool in the eastern Pacific, warm in the western Pacific and Indian oceans). A dry episode in the central Great Plains centered on about 2.4 ka is consistent with this teleconnection, but an earlier dry episode is centered on 3.8 ka, when eastern tropical Pacific SST was intermediate to warm. Sustained aeolian activity from about 9.6 to 6.5 ka occurred during a long interval of cool SST in the eastern tropical Pacific and warm SST to the west (sustained “La Nina-like” conditions), but this long dry period may also be explained by more direct effects of high summer insolation in North America.