Millennial- and centennial-scale vegetation and climate changes during the late Pleistocene and Holocene from northern New Mexico (USA)

Abstract

High-resolution pollen and magnetic susceptibility (MS) data from a sediment core from an alpine bog (3100 m) in the Sangre de Cristo Mountains (New Mexico) record variations in treeline elevation and in sedimentation for the last 14 ka (cal yr BP). Strong correspondence between the paleovegetation and the MS profile suggests that both records can be used to reconstruct past climatic conditions. The coldest conditions in this area occurred at the end of the late Pleistocene during the Pinedale glaciation and the Younger Dryas chron. A general warming trend took place during the early Holocene, lasting until ∼5.6 ka, when the warmest conditions occurred. A progressive climate cooling is then observed until today. Millennial- and centennial-scale changes are also observed throughout the vegetation and MS records. The higher amplitude millennial-scale cold events appear to correlate with the timing and duration of episodes of enhanced sea-ice drift in the North Atlantic and the lower amplitude centennial-scale cold events may correlate with periods of lower solar activity. A solar-climate connection is suggested from these records by a prominent ca 200-yr cycle in tree pollen abundance, which may correlate with the 208 yr Suess solar cycle. This study shows an immediate response of the vegetation (treeline) to climate change at millennial- and centennial-scales, probably related to variations in summer insolation and solar activity during the late Pleistocene and Holocene. Such high-resolution studies are very important in order to predict future climate change and particularly in very arid areas, where human activity and economies are strongly influenced by climate.