Are recent droughts in the plains and western U.S. comparable to historic droughts? Is climate change playing a role in recent drought conditions? If so, how? What do climate models suggest about the changing risk of drought in different areas of the country? What level of confidence should one ascribe to these model simulations of plausible futures? What role, if any, has climate change had on western forest fires? What role is climate change likely to play in forest fires regionally, in the future? What are the policy implications of these changes, coupled with demographic trends, for water supply and use in the western U.S.? Are there appropriate policies in place for managing western water now and into the future?
Moderator:
Dr. Anthony Socci, Senior Science Fellow, American Meteorological Society
Speakers:
Dr. Philip Mote, Member of the JISAO/SMA Climate Impacts Group and Affiliate Professor of atmospheric sciences University of WA, Seattle, WA
PowerPoint PDF Version
Dr. Anthony Westerling, Assistant Professor, School of Engineering & School of Social Sciences, Humanities, and Arts, University of California, Merced, CA; and Member of the California Applications Program & California Climate Change Center, Climate Research Division, Scripps Institution of Oceanography, University of California, San Diego, CA
Westerling HTML Version
PowerPoint PDF Version
Brad Udall, Director of the CU-NOAA Western Water Assessment, NOAA Earth System Research Laboratory, University of CO, Boulder, CO
Udall HTML Version
PowerPoint PDF Version
Drought in the Western U.S.
New insights are emerging into the ways our global climate system behaves and how such behavior affects drought in North America. First is the role of temperature in influencing evaporation and precipitation - the hydrologic cycle. Thus, in a warmer climate, both the incidence of droughts and of heavy precipitation could increase. Second, variations in ocean temperatures in key areas of the globe influence atmospheric circulation in ways that make droughts more likely. In addition to the long-known connection between tropical El Nino events and droughts in the Northwest, and between La Nina events and droughts in the Southwest and Southeast, new research highlights a role for the Indian ocean in enhancing the likelihood of droughts. Third, in river systems where snowmelt provides a large component of annual flow and winter temperatures are relatively mild, a small amount of warming can substantially alter the timing of water availability and of summer flows, as well as the flood risk; declines in spring snowpack and concomitant reductions in summer flows have already been observed in much of the West. Synthesizing observations, modeling, paleoclimate evidence, and outlooks for the future provides useful perspectives for managing, predicting, and preparing for droughts.
Climate Change and Forest Wildfire in the Western United States
Climate influences the risks of large wildfires in the western U.S. through the effects of temperature and precipitation on the quantity and dryness of the live and dead vegetation that fuels wildfires. Temperature, especially in spring and summer, has the greatest influence on wildfire in forests where fuels are abundant and winter snows store moisture for release in late spring and early summer. Precipitation has the greatest influence on wildfire in grasslands in dry basins and deserts where fuel is limited and excess moisture results in the growth of grasses and other fine fuels that quickly dry out in the summer dry season. Consequently, a trend toward increased spring and summer temperatures should be expected to result in increased wildfires in forests where snow plays an important role, but not necessarily elsewhere.
This is in fact what we observe in the documentary fire record for the western United States in recent decades. Available data for western grass and shrublands show little or no change in the frequency of large wildfires. Conversely, data for western forests show a substantial increase in the frequency of large wildfires and in the area burned in these fires, with most of the increase concentrated in a large forest area at mid-elevations of the Northern Rockies where snow is typically on the ground for much of the year. We also observe a lengthening of the fire season, with large fires igniting earlier in the summer in recent decades and burning longer.
Forest wildfire activity will increase if temperatures continue to increase. The response of forest wildfire to increased temperature is nonlinear, with large impacts occurring above specific thresholds that vary across the region. Continued increases in temperature may result in additional forest areas becoming vulnerable to increased wildfire, as new thresholds are crossed. Water resource management problems due to a warming climate and earlier runoff will be exacerbated by increased wildfire, as more frequent and intense fires reduce the capacity of forests to retain water and increase the likelihood of flooding and erosion. Western U.S. mountain forests also absorb and store a large share of the carbon that is taken up by vegetation in the United States each year, and an increase in the frequency and intensity of wildfires may result in less carbon being stored in these forests and more in the atmosphere, contributing to further global warming.
Future Water Policy in the Western U.S. – The Colorado River
The Colorado River serves approximately 30 million people in seven states and two nations, while also irrigating 3.5 million acres of very productive agriculture. By most measures these states California, Arizona, Nevada, Utah, Colorado, New Mexico and Wyoming -- are the fastest growing parts of the nation. Colorado River water is important to nearly every major city in and near the basin including Denver, Phoenix, Tucson, Santa Fe, Albuquerque, Las Vegas, Los Angeles and San Diego. The river is governed by what is arguably the most complicated legal structure of any river in the world including the first ever Interstate River Compact, a famous Supreme Court decree, Congressional legislation, and an International Treaty.
Much of the current planning in the basin has been based on the relatively benign climate of the early and mid- twentieth century. However, the basin has seen the most warming of anywhere in the lower 48 states during the last 30 years. In addition, the recent drought starting in 1999 has prompted much discussion amongst the basin states and provoked former Secretary of the Interior Norton to begin an Environmental Impact Statement to decide how to operate the major reservoirs and implement shortages during drought. This effort will be finished in late 2007. Several tree-ring based records of streamflow dating back to the 1500s indicate that the current drought, despite its apparent severity, is a relatively common event. Climate models, paleoclimatic studies, and basic atmospheric physics indicate that the basin may be very susceptible to reduced runoff in the future, adding yet another stress to an already taxed system.
Biographies
Dr. Philip Mote is a research scientist at the University of Washington, in the Climate Impacts Group (CIG), and an Affiliate Professor in the Department of Atmospheric Sciences. His research interests include Northwest climate variability and its effects on snowpack, streamflow, and forest fires. His work has documented, among other things, declines in spring snowpack in most of western North America. A frequent public speaker, delivering 50-70 public talks and 200+ media interviews per year, he has also written about 35 peer-reviewed scientific articles, has edited a book on climate modeling, published in 2000, and has also testified before the US Senate Commerce committee and state legislatures in Washington and Idaho. In 2003 he became the Washington State Climatologist. Dr Mote has an A.B. in physics from Harvard and a PhD in atmospheric sciences from University of Washington.
Dr. Philip Mote is a research scientist at the University of Washington, in the Climate Impacts Group (CIG), and an Affiliate Professor in the Department of Atmospheric Sciences. His research interests include Northwest climate variability and its effects on snowpack, streamflow, and forest fires. His work has documented, among other things, declines in spring snowpack in most of western North America. A frequent public speaker, delivering 50-70 public talks and 200+ media interviews per year, he has also written about 35 peer-reviewed scientific articles, has edited a book on climate modeling, published in 2000, and has also testified before the US Senate Commerce committee and state legislatures in Washington and Idaho. In 2003 he became the Washington State Climatologist. Dr Mote has an A.B. in physics from Harvard and a PhD in atmospheric sciences from University of Washington.
In addition to having published a couple of high-profile papers on climate and wildfire. Dr. Westerling also provides seasonal wildfire forecasts to the National Interagency Coordination Center for wildland fire management and budget planning. He is frequently invited to speak on issues related to climate impacts on wildfire at professional meetings, has been interviewed on radio programs around the US and abroad, has appeared on national network television news programs (NBC, ABC, CBS, CNN), and has been cited in numerous newspapers and electronic media nationally and internationally on the subject of climate change and wildfires.
Brad Udall is the Director of the Western Water Assessment at the University of Colorado. The Western Water Assessment is an interdisciplinary NOAA-funded project designed to assist water managers and other users of climate data and information. Recent Assessment projects using NOAA and CU scientists include a new 400-year long streamflow reconstruction of the Colorado River based on tree-rings, seasonal El Nino-based climate forecasts, and information about the likely impacts of climate change on water supplies in the Rocky Mountain West.
Mr. Udall is frequently requested to speak at events on the impacts of climate variability and change on western United States water resources. He has recently presented at the U.S Conference of Mayors annual meeting, the International Council for Local Environmental Initiatives, the National Association of Clean Water Agencies annual meeting, the Western Coalition of Arid States, the Western States Water Council, and the Arizona Water Resources Research Center. He was a contributor to the National Integrated Drought Information System plan. He was recently interviewed on National Public Radio on Colorado River shortage issues and was also quoted in the New York Times on Colorado River drought issues.
Mr. Udall has an engineering degree from Stanford and an MBA from Colorado State University. He was formerly a consulting engineer and the managing partner at Hydrosphere Resource Consultants, where he worked on interstate litigation on the North Platte River, endangered species on the Columbia River, future Colorado Front Range supplies, and shortage issues on the Colorado River.
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"Drought, Water, Wildfires and Climate Change
in the Western US - Historical Context and the Road Ahead" 