Year Established: 2013 Start Date: 2013-03-01 End Date: 2014-02-28
Total Federal Funds: $13,058 Total Non-Federal Funds: $6,464
Principal Investigators: Matthew Wooller
Abstract: Arctic Alaska is experiencing rapid changes in climate and hydrology. Successfully assessing how future climate change will affect water resources in the region is faced with two main challenges – geographically sparse climate data in an inaccessible region, and minimal context for how climate patterns have behaved over time – particularly during past warming events. These limitations can be overcome by the detailed analysis of biological archives that record climate data over the last several thousand years. Stable hydrogen and oxygen isotope ratios (expressed as D, 18O values) in wood cellulose are one such archive that is known to retain the isotopic signature of the plant source-water (e.g. precipitation). Our preliminary results indicate that18O values of willow (Salix spp.) wood cellulose collected across northwest Alaska are positively correlated with local isotopes in precipitation, which are a function of climate. Here we propose to further develop the use of wood isotopes as indicators of recent and past precipitation patterns in arctic Alaska. Through this work, we will observe how climate variability affects the geography of willow wood D and 18O values, including values on individual shrub rings that represent the annual climate conditions in the recent past (10s of years), and then analyze the D and 18O values of ancient willow samples we have already collected from dated lake sediment records to infer how the climate has changed over the last several thousand years. This project will proceed in three steps. First, we will collect and analyze the isotopes of modern willow stems growing near eight climate stations (maintained by federal agencies and the Water and Environmental Research Center, UAF) to test how mean and annual climate parameters are recorded as willow wood D and 18O values. Second, we will use these isotope-climate relationships to provide a proxy for recent climate patterns from areas without climate data. Third, we will analyze radiocarbon dated paleo-willow samples archived in a 10,000 year-long sediment record from a lake basin located in the Brooks Range foothills on the North Slope of Alaska. The majority of these modern and ancient wood samples have already been collected, and, in the case of the ancient samples, have already been radiocarbon dated. Funds are requested to analyze these samples for their stable isotopic composition. This project will serve as a chapter of a PhD student’s thesis. We propose an original idea applying a well-developed technique (plant cellulose isotope/climate correlations) to a new geographic area vulnerable to rapid climate change in the future. Results from this work will reveal how temporal changes in water resources in arctic Alaska have been affected by climate change in the past and potential changes in the future.