Climatic and ecological change in Arctic Alaska over the last 32,000 years inferred from lacustrine records and experimentsDaniels, WilliamcreatorRussell, JamesAdvisorGiblin, AnneAdvisorHuang, YongsongReaderMilliken, RalphReaderBrigham-Grette, JulieReaderBrown University. Department of Earth, Environmental, and Planetary Sciencessponsor2017xvii, 264 p.born digitalThesis (Ph. D.)--Brown University, 2017thesesContinued development of organic geochemical proxies for paleoclimate reconstructions are proving invaluable for understanding climate dynamics and climate-ecosystem interactions. Here I investigate the utility of the leaf wax hydrogen isotope proxy (δDwax) for inferring past changes in Arctic temperature and precipitation. I advance our understanding of the δDwax proxy through field surveys and growth chamber experiments, quantifying the effect that vegetation D/H fractionation imparts on δDwax in the tundra biome. These studies also improve constraints on the seasonality recorded by this proxy. Additionally, I present a paleotemperature reconstruction from sediments of Lake E5, one of few lakes in Alaska that contain sediments spanning the Last Glacial Maximum and Last Glacial Termination. The record, based on δDwax, provides new insights on Arctic climate amplification in the region, characterizes abrupt temperature changes in Northern Alaska, and identifies the opening of the Bering Strait as a critical influence on deglacial climate. Furthermore, I demonstrate that the D/H offset between terrestrial and aquatic waxes is a useful indicator of precipitation changes in Arctic paleoclimate records. Lastly, through modern lake manipulations and analysis of the Lake E5 paleolimnology, I demonstrate that the aquatic ecosystem is extremely sensitive to both climatic and nutrient perturbations and explore the mechanisms behind this sensitivity. In summary, I demonstrate that δDwax is a useful, but complex proxy in Arctic settings, and that paleoclimate reconstructions based on organic biomarkers provide an important context for understanding ecosystem-climate linkages.PaleoclimatologyArcticpaleolimnologyOrganic geochemistryLimnologyPlant ecophysiologyPlankton, FossilEnglishRPB2017061610.7301/Z0NS0SBWIn CopyrightCollection is open for research.dissertations