HR: 1340h
AN: PP53A-1386    [Abstracts]
TI: Combining Paleoenvironmental Data with Model Simulations to Understand Long-term Environmental Changes in the Upper Colorado Basin
AU: * Thompson, R S
EM: rthompson@usgs.gov
AF: USGS, Box 25046, MS980 Denver Federal Center, Denver, CO 80225 United States
AB: The Upper Colorado Basin (UCB) is an important source of water and power for cities, farms, and other interests from the plains of Colorado to the Pacific Ocean. The region is currently experiencing a multi-year drought that is affecting Colorado River flows and is implicated in the high mortality rate of pinyon pines in the region among other ecosystem impacts. Tree-ring studies indicate that large-scale droughts are a persistent feature of the past 700 years and severe droughts have occurred throughout the historic period. How will future climate change alter the magnitude and frequency of droughts in the UCB region? This presentation describes a research framework for integrating paleoenvironmental data with model simulations to assess both past and potential future changes in climate variability and the magnitude and frequency of drought for the UCB. Late Pleistocene and Holocene paleoenvironmental data are available from several areas within the UCB, with packrat midden studies available from the lower elevations and lacustrine and palynological records available from moist environments in the mountains. Collectively these data reveal that large-scale changes in the distribution of ecosystems have occurred through time in the UCB, suggesting variations in sources and amounts of precipitation over the course of centuries and millennia. These past variations greatly exceed those observed in the instrumental and dendrochronological data for the last several centuries. The latter data provide some context for assessing the severity of the current drought in regard to the current climate state, whereas the longer-term paleoenvironmental variations may be more similar in amplitude to potential future changes in climate in the UCB. Assessment of the potential effects of future climate change on the UCB requires: 1) devising means to integrate the instrumental, dendrochronological, and paleoecological records to provide a long-term synthesis of paleoclimatic variability, 2) developing a nested approach of global-regional-process models to simulate past conditions, 3) using the comparisons between the paleoenvironmental data and model simulations to evaluate model performance, and, 4) using the models to simulate potential future variations in environmental conditions in the UCB.
DE: 1600 GLOBAL CHANGE (New category)
DE: 1620 Climate dynamics (3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting