DGESL : Publications : Abstracts : Overpeck 1987

Pollen Time Series and Holocene Climate Variability of the Midwest United States

Overpeck, J.T.

1987 In: Abrupt Climate Change: Evidence and Implications (W.H. Berger and L.D. Labeyrie, eds.). D. Reidel Publishing Co., Holland, pp. 137-143

ABSTRACT

Time series of pollen data are important sources of information on climate variability within the century and millennium frequency bands. Twenty pollen records from the Midwestern United States were investigated using two methods of time series analysis in order to characterize Holocene climatic variability in this region. Event correlation among the twenty pollen records suggested that change in vegetation, and thus in climate, was episodic during the Holocene and was most substantial during the period between 11,500 and 10,000 yr B.P. Spectral analysis, cross-spectral analysis, and band-pass filtering of six of these pollen records revealed that a portion of the Holocene climate variability in the Midwest may have been quasi-periodic with a central frequency of approximately 1 cycle/1100 years. These preliminary results suggest that vegetation change in the century and millennium frequency bands must be considered in the context of systematic century- and millennium-scale climatic change.