THE ATMOSPHERE DURING THE YOUNGER DRYAS

One of the most dramatic climate change events observed in marine and ice core records is the Younger Dryas, a return to near-glacial condit ions that punctuated the last deglaciation. High-resolution, continuou s glaciochemical records, newly retrieved from central Greenland, reco rd the chemical composition of the arctic atmosphere at this time. Thi s record shows that both the onset and the termination of the Younger Dryas occurred within 10 to 20 years and that massive, frequent, and s hort-term (decadal or less) changes in atmospheric composition occurre d throughout this event. Changes in atmospheric composition are attrib utable to changes in the size of the polar atmospheric cell and result ant changes in source regions and to the growth and decay of continent al biogenic source regions.