The applicant will use this Polar Postdoctoral Fellowship to investigate how arctic ecosystems have responded to prior occurrences of warming in order to constrain current forecasts of ecosystem response to global change. The applicant's prior research indicates that Pliocene (app. 5 to 2 million years before present) surface temperatures in the Arctic may have been considerably warmer than previously thought. He will develop this idea through a multi-proxy approach to reconstructing arctic temperature and precipitation in the Pliocene by analyzing stable isotopes of carbon and nitrogen in the collagen of fossil bones from an array of preserved mammals, and will determine quantitative metrics of ecosystem structure. These metrics will then be compared with values from the modern boreal forest to identify the significant characteristics that differ between the two biomes. Empirical estimates of temperature and relative humidity will be compared with model simulations of Pliocene Arctic climates to identify climate feedbacks that may amplify climate sensitivity at high latitudes.
