Tuesday, May 12, 2009
Developing hydroclimatic reconstructions for water resources management in the Pacific Northwest
Water resource managers in the Pacific Northwest face a number of challenges including growing population (especially urban), emerging water issues such as the protection and restoration of endangered salmon populations, natural climate variability (particularly drought and decadal precipitation variability), and climatic change. The instrumental record contains only a subset of the range of natural variability possible, and longer records of streamflows based on tree-ring chronologies provide an important avenue for providing an improved understanding of regional hydroclimate uncertainty. Furthermore, a growing body of evidence demonstrates that climate in the western U.S has changed markedly in the 20th century, and there is a need to relate the droughts in the past to current climatic conditions (which in particular are now believed to be systematically warmer than in the early part of the instrumental record). By combining tree-ring chronologies with hydrologic simulations associated with systematically warmer temperatures expected for the 21st century, improved projections of future drought conditions will be produced. Water managers in the PNW have expressed interest in developing long-term hydrologic reconstructions in order to better anticipate the range of future climate conditions and their impacts on water resources. This talk will address the first and second parts of this project, which is identification of locations and variables of interest to water managers and the development of a network of suitable tree ring chronologies to address those. The talk will focus on the development of new chronologies, the climatically relevant signals, and the quality of regional and subregional streamflow reconstructions.
Jeremy Littell is a Research Scientist with the Climate Impacts Group.