2024-2025: Science and Society: Connie Woodhouse

Connie Woodhouse
University of Arizona 

Biography

I am currently a Regents professor emerita in the School of Geography, Development, and Environment and at the Laboratory of Tree-Ring Research. I retired from a faculty position in spring 2023 but continue to work on a variety of research projects.
My areas of expertise include dendrochronology, paleoclimatology, and climatology. Much of my research focuses on understanding the hydroclimate of the past using tree-ring data to inform current environmental and societal problems, with a focus on major watersheds in western North America. While paleoclimatology is at the heart of my work, it inevitably extends to include the investigation and understanding of current controls on hydroclimate. I am also motivated to strengthen the relevance and applicability of my research to the challenges of managing natural resources (especially water) in the face of changing demands, climate extremes, and climate change impacts. Some of my current research projects include developing streamflow and climate reconstructions for the upper Colorado River, Rio Grande, and Missouri River basins as well as investigating the potential to reconstruct past temperatures from tree line bristlecone pine in the Rocky Mountains of Colorado.
I completed a master’s degree in geography at the University of Utah in 1989 and a Ph.D. in geosciences at the University of Arizona in 1996. I became a fellow of the American Geophysical Union in 2022.


Abstract: Tree Rings and Colorado River Streamflow: Can the Past Inform the Future?

The Colorado River, a critical source of water for over 40 million people and 5.5 million acres of irrigated agriculture, has made headlines as sustained drought and warming temperatures have diminished its supply.  Colorado River streamflow is highly variable, and the gage record reflects periods of drought and wetness over the past 115 years, but does this record capture the full range of variability possible over longer time scales? Are drought conditions of the past several decades largely due to climate change or is this drought a part of natural climate variability?  In order to address these questions, a longer record of streamflow is needed.  Tree rings can be used to extend records of climate and hydrology back in time, and have been successfully used to reconstruct Colorado River streamflow centuries back in time. These extended records allow us to place the gage record of streamflow into a long-term context. An early tree-ring record of Colorado River flow highlighted what is now obvious, that the 1922 Colorado River Compact was based on an unusually wet span of years, resulting in over-allocation of the river’s resources.  Reconstructions of past streamflow also clearly document the much broader range of conditions that have occurred in the more distant past, including droughts that were longer than any we have experienced in the period of the gage record. While valuable for this long-term context, there are other ways that reconstructions of past streamflow have been found useful.  These include providing worst case scenarios for drought planning and sensitivity-testing for water system response to different sequences of annual streamflow. However, given warming temperatures, are records of past streamflow applicable to the future? It is true that the past is not an analogue for the future. However, plausible future scenarios for water management include the range of conditions documented by paleohydrologic data with the added influence of warming. The blending of these two is being accomplished in a variety of ways, offering important insights for future planning.