Orbital- and millennial-scale vegetation and climate changes of the past 225 ka from Bear Lake,Utah–Idaho (USA) |
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| Institution: | 1. Center for Environmental Sciences and Education, and Quaternary Sciences Program, Northern Arizona University, Flagstaff, AZ 86011, USA;2. Department of Earth and Planetary Sciences, Northrop Hall, University of New Mexico, Albuquerque, NM 87131, USA;3. Departamento de Estratigrafía y Paleontología, Universidad de Granada, Fuente Nueva s/n, 18002, Granada, Spain;1. California State University, Fullerton, Department of Geological Sciences, Fullerton, CA 92834, USA;2. University of Southern California, Department of Earth Sciences, Los Angeles, CA 90089, USA;1. Department of Earth Science and Geography, Vassar College, Poughkeepsie, NY, 12604, USA;2. Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM, 87131, USA;1. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10601, USA;2. California State University, Fullerton, Department of Geological Sciences, Fullerton, CA 92834, USA;1. Department of Geology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA;2. Department of Plant Biology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA;3. Department of Atmospheric Sciences, University of Hawaii at Mānoa, Honolulu, HI, 96822, USA;4. Illinois State Geological Survey, University of Illinois Urbana-Champaign, Champaign, IL, 61820, USA;1. Department of Geosciences, The University of Arizona, 1040 E 4th St, Tucson, AZ 85721, USA;2. Department of Geology and Geophysics, University of Wyoming, Laramie, WY, USA;3. School of Earth Sciences and Environmental Sustainability, Northern Arizona University, Arizona, USA;4. School of Earth and Environmental Sciences, The University of Manchester, Manchester, UK |
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| Abstract: | Continuous high-resolution pollen data for the past 225 ka from sediments in Bear Lake, Utah–Idaho reflect changes in vegetation and climate that correlate well with variations in summer insolation and global ice-volume during MIS 1 through 7. Spectral analysis of the pollen data identified peaks at 21–22 and 100 ka corresponding to periodicities in Earth's precession and eccentricity orbital cycles. Suborbital climatic fluctuations recorded in the pollen data, denoted by 6 and 5 ka cyclicities, are similar to Greenland atmospheric temperatures and North Atlantic ice-rafting Heinrich events. Our results show that millennial-scale climate variability is also evident during MIS 5, 6 and 7, including the occurrence of Heinrich-like events in MIS 6, showing the long-term feature of such climate variability. This study provides clear evidence of a highly interconnected ocean–atmosphere system during the last two glacial/interglacial cycles that extended its influence as far as continental western North America. Our study also contributes to a greater understanding of the impact of long-term climate change on vegetation of western North America. Such high-resolution studies are particularly important in efforts of the scientific community to predict the consequences of future climate change. |
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