Date: 03/25/2009

Final
CWCB Climate Change Study

COMMITTEE ON JOINT AGRICULTURE AND NATURAL RESOURCES

Votes: View--> Action Taken:
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07:36 AM -- CWCB Climate Change Study

Veva Dehaza, Colorado Water Conservation Board (CWCB), explained that the CWCB commissioned a study of climate change that synthesizes data from other climate change studies. The report, “Colorado Climate Change: A Synthesis to Support Water Resource Management and Adaptation” focuses on observed trends and projections of temperature, precipitation, snow and runoff. The report gives water resource managers a synthesis of information about what is expected for Colorado’s climate over the next few decades to help them plan now for drought and adaptation to climate change. This report is available at www.cwcb.state.co.us/Home/ClimateChange/ClimateChangeInColoradoReport/

090325AttachA.pdf

07:38 AM

Brad Udall, University of Colorado, explained that the climate change report was prepared by the Western Water Assessment, a University of Colorado-National Oceanic and Atmospheric Administration (NOAA) partnership, and included scientists from the NOAA Earth System Research Laboratory, the CU Cooperative Institute for Research into Environmental Sciences, and Colorado State University Colorado Climate Center. He explained that in Colorado, temperatures have increased by approximately 2F between 1977 and 2006. He also explained how increasing temperatures are affecting the state’s water resources. Between 1978 and 2004, the spring pulse in Colorado has shifted earlier by two weeks. Several studies suggest that shifts in timing and intensity of stream flows are related to warming spring temperatures. The timing of runoff is projected to shift earlier in the spring, and late-summer flows may be reduced. He explained that climate models project Colorado will warm by 2.5F by 2025 and 4F by 2050, relative to the 1950–99 baseline. Mr. Udall responded to questions from the committee about projected temperature changes and when they will occur throughout the year.

07:49 AM

Mr. Udall explained that for the Upper Colorado River Basin, multi-model average projections suggest decreases in runoff ranging from 6 percent to 20 percent by 2050 compared to the 20th century average. He also responded to questions from the committee about observed temperature changes in Colorado including the decline in the average temperature recorded in Lamar. He explained that cleaner air may contribute to higher temperature readings at some locations because pollution reflects light that helps to lower temperature. He also described how stream flows in the Colorado River Basin may be affected by climate change and how this will impact the ability of the Colorado River to satisfy water demands in Colorado and from lower basin states. Mr. Udall also described dust on snow and how it affects the timing and amount of runoff.

08:01 AM

Ms. Dehaza explained that the Colorado Water Conservation Board received authorization from the Colorado General Assembly to use money from the Colorado Water Conservation Board Construction Fund to pay for Phase II of the Climate Change Report. This study will address data shortfalls identified in the Phase I of study. She also described a public education program that is being developed with Mr. Udall and the Western Water Assessment.