Ancient Tree Ring Archives in the U.S. Great Lakes Region



Rather than being a seamless transition from Late Glacial Maximum to the start of the Holocene between 15,000 and 8000 years ago, the warming during this period was punctuated by abrupt climatic instabilities. These include the Younger Dryas cold event, the Preboreal Oscillation, and an isolated cooling event around 8200 years ago (see Figure 1, bottom right).