Project Methods:
The last 2000 years of sediment for each lake will be analyzed to extract quantitative estimates of past summer temperature and other climate parameters. We will rely on three established proxies widely used in similar reconstructions of Holocene climatic change for quantitative estimates of climate: chironomid assemblages, oxygen isotopes, and lamination characteristics. In addition, as part of our multi-proxy approach, we will analyze other biological, geochemical, or sedimentological paleoenvironmental indicators from each lake. These “secondary proxies”, including diatom and pollen assemblages, or biogenic silica and organic carbon contents, often carry important signals of ecological and geomorphological processes that provide context, crosschecks, and comparisons for the primary proxies. In addition to varve counts where possible, age models for each sediment core will be based on 137Cs, 210Pb and 14C measurements.
