Both natural climate and ecosystems may respond abruptly to gradual forcings. During the late glacial time window between 14,000 and 10,000 years BP, large magnitude changes occurred within decades. This project will examine the records from integrated close-interval samples of two different climate proxies with different response rates in the climatically sensitive Midwest region south of the Great Lakes. We will use stable isotopes present in lake sediment carbonates as a proxy measure of almost instantaneous response to changes in regional precipitation patterns. We will use pollen deposition as a proxy for regional vegetation (and indirectly climate), giving a record with a time lag. The area including Ohio, Indiana, Michigan, and Illinois will be examined. These sites will allow direct comparison of response rate of different systems during the two warming events in the late glacial around 13,000 BP, and in the Younger Dryas Chron around 10,200 BP.
Isotope and Pollen Stratigraphy of Abrupt Late Glacial Climate Events in the Upper Midwest