Mid-Holocene climate in Northern Minnesota |
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| Institution: | 1. Department of Cardiothoracic Surgery, NYU Langone Medical Center, New York, NY, United States;2. Department of Cell Biology, New York University School of Medicine, New York, NY, United States;3. Department of Pathology, New York University School of Medicine, New York, NY, United States;4. NYULMC Genome Technology Center, NYU Langone Medical Center, New York, NY, United States;5. Center for Health Informatics and Bioinformatics, NYU Langone Medical Center, New York, NY, United States;1. Information and Control Institute, Hangzhou Dianzi University, Hangzhou 310018, PR China;2. Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong |
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| Abstract: | Study of Holocene ostracodes and diatoms from Elk Lake, in North-Central Minnesota, indicates that the local climate of the mid-Holocene can be subdivided into three intervals. Throughout interval 1 (ca. 7800 to 6700 yr B.P.), climate was colder and much drier than today. During intervals 2 and 3 (ca. 6700 to 4000 yr B.P.) average mean-annual air temperatures approached the modern mean (3.7°C), but warm summers persisted throughout interval 2, whereas during interval 3 warm summers fell into discrete episodes. Furthermore, average mean-annual precipitation was about 85 and 90% of modern during intervals 2 and 3, respectively. Transition times between the principal intervals were less than 50 yr. The expected effects of a retreating Laurentide Ice Sheet that initially maintained a winter-style circulation, followed by transitional climate states, and finally a near-modern circulation pattern may explain these local climatic events. |
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