The last (Koy-Yukon) interglaciation in the Yukon: Comparisons with holocene and interstadial pollen records

Abstract

Paleoclimatic reconstructions for the last interglacial (LIG), isotope substage 5e, have achieved new importance for testing climate model simulations and predicting the outcome of global warming. LIG deposits at Ch'ijee's Bluff, northern Yukon, display high fossil spruce pollen frequencies, extralimital species and a lack of interglacial permafrost; all evidence of a warmer than present climate at the site. Comparisons between the Ch'ijee's Bluff LIG pollen record and Late glacial-Holocene pollen stratigraphy demonstrates a high degree of similarity that implies similar patterns and rates of species migration and regugia. Compared to Mid and Early Wisconsinan pollen stratigraphy, the climate of the Wisconsinan interstades was not as warm as that of the LIG, or today's. LIG warmth was insufficient for the spread of pine into northern Yukon. Alder, so important in the northern forests now, appears to have had a less important role during the LIG, perhaps indicating less widespread permafrost and paludification. Fossiliferous deposits beneath Hungry Creek till (Hughes et al., 1981) are reassigned to the LIG.