Diaz, H. F., J. T. Andrews, and S. K. Short, 1989: Climate variations in northern North America (6000 B.P. to present) reconstructed from pollen and tree ring data. Arctic Alpine Res., 21, 45-59.


The characteristic anomaly patterns of modern surface temperature and precipitation are compared to tree ring indices (0-300-yr) and fossil pollen (0-6000-yr) variations in northern North America. The data base consists of 245 climate stations, 55 tree ring chronologies, 153 modern pollen collections, and 39 fossil pollen sites. A few areas exhibit relatively high climatic sensitivity, displaying generally consistent patterns during alternate warm and cold periods, regardless of time scales. The surface changes are related to the redistribution (i.e., changes in the mean position and strength) of the planetary-scale waves and to N-S shifts in the mean boundary of the Arctic Front. The zone where the largest changes occur is typically located along the mean present-day boundary between Arctic and Pacific airstreams. Establishing plausible relationships between vegetation responses and concomitant changes in atmospheric circulation patterns increases the confidence that the paleoclimatic signals are indeed related to large-scale circulation changes.