A Southern Hemisphere perspective on the last great global warming

Date & time

1–2pm 29 March 2018

Location

Jaeger 1 Seminar Room, RSES

Speakers

Aaron Putnam (University of Maine)

Event series

Contacts

 Adele Morrison

A spectacular warming terminated the last ice age. This termination was the largest natural warming of the recent geologic past and represents an excellent natural experiment that can be studied in order to clarify the underlying dynamics of Earth’s climate system. Here I will present 10Be and 14C chronologies of Southern Hemisphere mid-latitude glacier extent that record extensive mountain glacier recession and atmospheric warming during the earliest millennium or two of Heinrich Stadial 1 (HS1; about 17,800 – 14,700 years ago). Much of the full glacial-to-interglacial reduction of glacier ice and atmospheric temperature rise went to completion during this interval. Taken together with other Southern Hemispheric temperature reconstructions, these data indicate that rapid warming encompassed at least the southern quarter of the globe during this time. In addition, I will present preliminary glacier chronologies from mid-latitude mountain chains in the Northern Hemisphere that hint at a similar timing and pace of ice recession as in southern mid-latitudes. This interhemispheric signature of ice recession coincided with collapse of northern ice sheets, and the imposition of stratification and winter-centric cooling in the North Atlantic. On the basis of these observations from glacial chronologies in both hemispheres, I will offer some preliminary ideas as to the mechanisms responsible for this big, fast, and global warming that, by this hypothesis, terminated the ice age.

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