Deep Lake Minnesota 12,000 Year Sediment Data Hu, F.S. Hu, F.S. earth science/paleoclimate/paleolimnology (delta 13C,carbonate,null,per mil VPDB,null,paleolimnology,null,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (varve thickness,null,null,centimeter,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (age,null,null,calendar year before present,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (delta 18O,carbonate,null,per mil VPDB,null,paleolimnology,null,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology (Deep Lake>LATITUDE 47.68389>LONGITUDE -95.39944) Recent studies of the Greenland ice cores have offered many insights into Holocene climatic dynamics at decadal to century timescales. Despite the abundance of continental records of Holocene climate, few have sufficient chronological control and sampling resolution to compare with the Greenland findings. Butannually laminated sediments (varves) from lakes can provide high-resolution continental palaeoclimate data with secure chronologies. Here we present analyses of varved sediments from Deep Lake in Minnesota, USA. Trends in the stable oxygen-isotope composition of the sedimentary carbonate indicate a pronounced climate cooling from 8.9 to 8.3 kyr before present, probably characterized by increased outbreaks of polar air, decreased precipitation temperatures, and a higher fraction of the annual precipitation falling as snow. The abrupt onset of this climate reversal, over several decades, was probably caused by a reorganization of atmospheric circulation and cooling of the Arctic airmass in summer that resulted from the final collapse of the Laurentide ice near Hudson Bay and the discharge of icebergs from the Quebec and Keewatin centres into the Tyrell Sea. The timing and duration of this climate reversal suggest that it is distinct from the prominent widespread cold snap that occurred 8,200 years ago in Greenland and other regions. No shifts in the oxygen-isotope composition of sediment carbonate occurred at 8.2 kyr before present at Deep Lake, but varve thickness increased dramatically, probably as a result of increased deposition of aeolian dust. Taken together, our data suggest that two separate regional-scale climate reversals occurred between 9,000 and 8,000 years ago, and that they were driven by different mechanisms. STUDY NOTES: Deep Lake Minnesota Sediment Data, used for Abrupt Holocene Climate Change analysis by Hu et al. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Hu, F.S. 2000-01-01 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/5475 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_isotopes.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/readme_hu1999.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_pollen.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_varves.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_hu1999.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_c14.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_isotopes.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/readme_hu1999.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_pollen.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_varves.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_hu1999.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_c14.txt English https://www.ncdc.noaa.gov/paleo/study/5475 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_isotopes.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/readme_hu1999.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_pollen.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_varves.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_hu1999.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greatplains/deeplake/deeplake_c14.txt Hu, F.S.. 1999. Abrupt changes in North American climate during early Holocene times. Nature Vol. 400, pp. 437-440 START YEAR: 11910 cal yr BP * END YEAR: 7480 cal yr BP -95.39944 47.68389 -95.39944 47.68389