As Colorado鈥檚 climate continues to warm, those who manage or use water in the state will likely face significant changes in water supply and demand, according to a released today by the and the .
Rising temperatures will tend to reduce the amount of water in many of Colorado鈥檚 streams and rivers, melt mountain snowpack earlier in the spring, and increase the water needed by thirsty crops and cities, according to the new report, 鈥淐limate Change in Colorado: A Synthesis to Support Water Resources Management and Adaptation,鈥� which updates and expands upon an initial report released in 2008.
The Colorado report comes on the heels of international and national assessments that discuss likely impacts of climate change in broad regions, and it leverages those assessments to provide state-specific information. Because Colorado is located between an area likely to dry further (the U.S. Southwest) and one likely to get wetter (Northern Great Plains), our precipitation future is less certain. 听
鈥淒espite some uncertainties around precipitation, it鈥檚 clear that as temperatures rise in Colorado, there will be impacts on our water resources,鈥� said Jeff Lukas, lead author of the new report and a researcher at the Western Water Assessment, a program of the University of Colorado Boulder funded by the National Oceanic and Atmospheric Administration.
鈥淎lready, snowmelt and runoff are shifting earlier, our soils are becoming drier, and the growing season has lengthened,鈥� Lukas said. 鈥淲ildfires and heat waves have become more common, too. Climate projections suggest those trends鈥�all of which can affect water supply and demand鈥�will continue.鈥�
The newest climate models are split on whether the future will see increasing, decreasing or similar amounts of annual precipitation in Colorado. Even if the future brings more precipitation, the report notes, skiers, farmers and cities may not benefit because a warmer atmosphere will pull more moisture out of the state鈥檚 snowpack, soils, crops and other plants.
In producing 鈥淐limate Change in Colorado,鈥� the authors sought to provide information that would be useful to people involved in making long-term decisions about Colorado鈥檚 water in the face of climate change.
鈥淭his report will help to inform critical products like the Statewide Water Supply Initiative (SWSI) and Colorado鈥檚 Water Plan,鈥� said James Eklund, Colorado Water Conservation Board director. 鈥淭his report will add value, just as the 2008 report was widely used by the state and other entities to inform their long-term planning processes such as the Colorado Drought Mitigation and Response Plan and the city of Denver鈥檚 Climate Adaptation Plan.鈥�
Among the findings presented in the new report:
- Colorado has warmed: Statewide average annual temperatures are 2 degrees Fahrenheit higher than they were three decades ago.
- Climate models indicate that the state鈥檚 average annual temperature will continue to increase, by 2.5 to 6.5 degrees by 2050.
- A 2-degree increase would make Denver鈥檚 temperatures in 2050 more like Pueblo鈥檚 today.
- A 4-degree increase would make Denver more like Lamar in southeastern Colorado, and a 6-degree shift would push Denver鈥檚 temperatures beyond any found in Colorado today, to more like those in Albuquerque, New Mexico, today.
- Future warming in the state is likely to lead to more heat waves, wildfires and droughts. Observations show there have already been increasing trends in these three extremes over the past 30 years.
- Warmer temperatures and other changes (dust on snow) mean that snowpack is melting earlier, on average, by one to four weeks compared with 30 years ago. This creates a strain for farmers and other users who draw water directly from rivers.
- Colorado has seen no long-term increase or decrease in total precipitation or heavy rainfall events. Climate models are split about Colorado鈥檚 future precipitation, showing a range of possible outcomes from a 5 percent decrease in precipitation to an 8 percent increase by midcentury.
- Climate models tend to show a shift toward higher midwinter precipitation across the state.
- Hydrology models show a wide range of outcomes for annual streamflow in Colorado鈥檚 river basins, but an overall tendency towards lower streamflow by 2050, especially in the southwestern part of the state.
The Western Water Assessment (WWA) is part of the Cooperative Institute for Research in Environmental Sciences (CIRES), a joint institute of 抖阴旅行射-Boulder and the National Oceanic and Atmospheric Administration (NOAA). The Colorado Water Conservation Board (CWCB) is a division of the Colorado Department of Natural Resources and spearheads the state鈥檚 climate change adaptation efforts. 听听
Co-authors of the report are Joseph Barsugli of CIRES and NOAA鈥檚 Earth System Research Laboratory (ESRL), Nolan Doesken of Colorado State University and the Colorado Climate Center, Imtiaz Rangwala of WWA, and Klaus Wolter of CIRES and ESRL.
Read a summary of the report at , and see the full report at .听
