A diatom-based reconstruction of drought intensity, duration, and frequency from Moon Lake, North Dakota: a sub-decadal record of the last 2300 years |
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| Authors: | Kathleen R Laird Sherilyn C Fritz Brian F Cumming |
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| Institution: | (1) Department of Ecology and Limnological Research Center, University of Minnesota, Minneapolis, MN 55455, USA;(2) Present address: Paleoecological Environmental Assessment and Research Lab (PEARL) Department of Biology, Queen's University, Kingston, Ontario, Canada, K7L 3N6;(3) Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, PA 18015, USA |
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| Abstract: | Diatom assemblages preserved in sediment cores from closed-basin lakes can provide high-resolution records of past hydrologic and climatic conditions, including long-term patterns in the intensity, duration, and frequency of droughts. At Moon Lake, a closed-basin lake in eastern North Dakota, a comparison of diatom-inferred salinity and the precipitation-based Bhalme-Mooley Drought Index (BMDI) over the last 100 years was highly significant, suggesting that the diatom record contains a sensitive archive of past climatic conditions. A sub-decadal record of inferred salinity for the past 2300 years indicates that extreme droughts of greater intensity than those during the 1930s 'Dust Bowl' were more frequent prior to A.D. 1200. This high frequency of extreme droughts persisted for centuries and was most pronounced from A.D. 200–370, A.D. 700–850 and A.D. 1000–1200. A pronounced shift to generally wetter conditions with less severe droughts of shorter duration occured at A.D. 1200. This abrupt change coincided with the end of the 'Medieval Warm Period' (A.D. 1000–1200) and the onset of the 'Little Ice Age' (A.D. 1300–1850). |
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| Keywords: | drought diatoms paleoclimate Northern Great Plains paleosalinity Medieval Warm Period Little Ice Age |
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