High resolution paleoclimate records and scenarios of climate change and variability

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The objective of the proposed research is to expand a network of moisture-sensitive tree-ring chronologies in the western interior and apply these high-resolution paleoclimatic data to a) creating long (300-800 years) proxy records of annual and seasonal precipitation and streamflow, b) determining the long-term probability of hydroclimatic conditions (drought, low flows) below specific thresholds, c) identifying the length, frequency and forcing of hydroclimatic cycles, d) testing and verifying global climate model (GCM) simulations of precipitation and drought, e) determining the response of ecosystems to climatic variability, and f) developing scenarios of future climate change and its impacts. Research on objectives c) to f) will involve collaboration with colleagues in the earth, atmospheric, biological and social sciences. The scientific approach will include the strategic sampling of tree rings at dry sites to increase the length and density of our reconstructions of drought and streamflow. Research will be targeted at sites where paleoecological records have been derived from lake sediments, and in watersheds where climate impact scenarios forecast decreasing flow. We will correlate our tree-ring records of prairie drought with instrumental and proxy records of late-Holocene shifts in aridity, sea surface temperatures anomalies, and the climatology of recent droughts. The frequency distributions of hydroclimatic events of specific magnitudes will be compared between our tree-ring records and GCM control runs and greenhouse-forced simulations of future climate. The significance of the proposed research is the use of high-resolution paleoclimatic (tree-ring) data to gain a longer perspective on stream flow and drought than provided by instrumental records, and the application of paleoclimatic data to the process of generating scenarios of future climate. Novel aspects include relating the climate variability simulated by GCMs to the climate signals captured by tree rings, coupling high-resolution paleoclimatic and paleoecological records to investigate the response of ecosystems to climatic variability, and delivering paleoclimatic data to decision makers responsible for the planning of adaptation to climate variability and change.