Mid-Wisconsin seasonal temperatures reconstructed from fossil beetle assemblages in eastern North America: comparisons with other proxy records from the Northern Hemisphere

Mutual climatic range (MCR) analysis was applied to 15 North American beetl e assemblages spanning the interval from > 52 000 to 17 200 yr BP, bracketi ng a Mid-Wisconsin interstadial interval. The analyses yielded estimates of mean July (TMAX) and mean January (TMIN) temperatures. The oldest assembla ge (> 52 ka) yielded TMAX values 7.5-8 degrees C lower than present and TMI N values 15-18 degrees C lower than present. A Mid-Wisconsin interstadial w arming dating from 43.5-39 ka was rapid and intense. Ar the peak of the war ming event, about 42 ka, TMAX values were only 1-2 degrees C lower than mod ern. This level of amelioration apparently lasted only about 2000-3000 yr. By 23.7 ka, TMAX values declined to 11.5-10 degrees C lower than modern, bu t another, small-scale amelioration is indicated by assemblages dating from 20.5 to 19.7 ka. The interstadial event recorded from the sire at Titusvil le, Pennsylvania closely matches the timing and intensity of the climate ch ange estimated from British beetle faunas in the Upton Warren interstadial. Another warm interval (ca. 31-32.5 ka) has been documented from fossil bee tle assemblages in Europe and North America. Copyright (C) 1999 John Wiley & Sons, Ltd.