Upper Midwest USA Last Millennium Summer 2m Air Temperature Wahl, E.R.; Diaz, H.F.; Ohlwein, C. Wahl, E.R. Diaz, H.F. Ohlwein, C. Air Temperature Reconstruction Medieval Climate Anomaly (MCA) North Atlantic Oscillation earth science/paleoclimate/climate reconstructions|pollen (age,null,null,year Common Era,null,climate reconstructions|pollen,null,null,N,null) earth science/paleoclimate/climate reconstructions|pollen (surface air temperature,null,percentile,degree Celsius,summer,climate reconstructions|pollen,null,regression analysis,N,1st percentile; logistic generalized linear model; 2m air temperature) earth science/paleoclimate/climate reconstructions|pollen (surface air temperature,null,percentile,degree Celsius,summer,climate reconstructions|pollen,null,regression analysis,N,50th percentile; logistic generalized linear model; 2m air temperature) earth science/paleoclimate/climate reconstructions|pollen (surface air temperature,null,percentile,degree Celsius,summer,climate reconstructions|pollen,null,regression analysis,N,99th percentile; logistic generalized linear model; 2m air temperature) earth science/paleoclimate/reconstructions (Dark Lake (DARKLAKE)>LATITUDE 45.275>LONGITUDE -91.475) (Little Pine Lake (LITTLPIN)>LATITUDE 45.28333>LONGITUDE -91.48333) (Ruby Lake (RUBYLAKE)>LATITUDE 45.26667>LONGITUDE -91.45834) We present a reconstruction of mean summer temperature for the northern Midwest of theUSA based on lacustrine pollen records from three different lakes in Wisconsin. The results suggest a relatively warm period during the earlier part of the record (~1200–1500 CE) followed by a cooler Little Ice Age (~1500–1900) and a subsequent warming to modern conditions. The reconstructed modern summer mean temperature is in good agreement with observations, and the decades of the 1930s to 1950s appear to be the warmest such period in the proxy record (through 1974). Analyses of circulation features associated with the warmest summers in the recent climate record suggest a prevalence of continental ridging accompanied by generally dry conditions during these warm summers in the Midwest. Drought reconstruction using the Palmer Drought Severity Index (PDSI) and tree-ring records as predictors also yield relatively dry conditions in medieval times for the central US. As reported in a number of recent studies, possible forcing mechanisms include La Niña-like conditions in the equatorial Pacific and warmer than average waters in the tropical Indo-western Pacific Ocean possibly coupled to a positive mode of the AMO/ NAO North Atlantic circulation pattern. STUDY NOTES: Fossil pollen from three lakes in Wisconsin USA are used (Dark Lake, Ruby Lake, Little Pine Lake) along with modern pollen-climate relationships from the North American Pollen Data Base NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Wahl, E.R. Investigator : Diaz, H.F. Investigator : Ohlwein, C. 2014-09-02 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/17133 https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2012/wahl2012-darklake.txt https://www1.ncdc.noaa.gov/pub/data/paleo/pollen/recons/liadata.txt https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2012/wahl2012-littlepine.txt https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2012/wahl2012-rubylake.txt https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2012/wahl2012-darklake.txt https://www1.ncdc.noaa.gov/pub/data/paleo/pollen/recons/liadata.txt https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2012/wahl2012-littlepine.txt https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2012/wahl2012-rubylake.txt English https://www.ncdc.noaa.gov/paleo/study/17133 https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2012/wahl2012-darklake.txt https://www1.ncdc.noaa.gov/pub/data/paleo/pollen/recons/liadata.txt https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2012/wahl2012-littlepine.txt https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2012/wahl2012-rubylake.txt Wahl, E., H. Diaz, and C. Ohlwein2012A pollen-based reconstruction of summer temperature in central North America and implications for circulation patterns during medieval timesGlobal and Planetary Change84-8566-7410.1016/j.gloplacha.2011.10.005 START YEAR: 1045 AD * END YEAR: 1965 AD -91.48333 45.26667 -91.45834 45.28333