http://www.arizonapirg.org/home/reports/report-archives/our-water-our-future/our-water-our-future http://www.arizonapirg.org/home/reports/report-archives/our-water-our-future/our-water-our-future/our-water-our-future-policy-options-to-safeguard-water-resources-in-arizona In Arizona, the most recent drought of the past decade has surpassed the worst drought in the last http://www.arizonapirg.org/home/reports/report-archives/our-water-our-future/our-water-our-future/our-water-our-future-policy-options-to-safeguard-water-resources-in-arizona Wed, 25 Jul 2007 14:57:59 -0500 http://www.arizonapirg.org/home/reports/report-archives/our-water-our-future/our-water-our-future/less-snow-less-water-climate-disruption-in-the-west In the American West, no other effect of climate disruption is as significant as how it endangers the region’s already scarce snowpacks and water supply. With the inherent vulnerability of the dry West to even small changes in the snow-water cycle, these risks alone present ample reason for Westerners to take action to protect this special region. The Likely Effects of Climate Disruption on the West’s Water Scientists believe that climate disruption in the West likely will result in more heat, less snowpack, and earlier snowmelt and runoff. This may be accompanied by other adverse effects, including increased intensity, frequency, and duration of drought. ? More heat. Temperature increases in the West are likely to be even greater than the projected 3° to 10°F worldwide increase by the end of the 21st Century, compared to 1990. The heating is likely to be greater in the winter than in the summer and at higher elevations than in lowlands, with significant implications for snowpacks and water availability. ? Smaller snowpacks. It is very likely that more winter precipitation will fall as rain instead of snow, periods of snowpack accumulation will be shorter, and snowpacks will be smaller. ? Earlier snowmelt. Warming earlier in the year very likely will melt snowpacks sooner. Peak water flows would occur that much sooner than the summertime peak water needs of cities, farmers and ranchers, and others. ? More evaporation and dryness. Higher temperatures would increase evaporation from streams and reservoirs, soil dryness, and the needs of crops and other plants for supplemental water. ? More flood-control releases. Warming in the mountains in late winter and early spring very likely will increase snowmelt and river flows then, and reduce them later in the year. The risk of flooding likely will increase, and water managers may be forced to make flood-control releases more often from reservoirs, leaving less water to be stored for summertime needs. ? Less groundwater. Snowpacks also are essential contributors to the West’s groundwater, so reduced snowpacks could reduce groundwater supplies, too. ? More legal restrictions. Environmental constraints, which sometimes now limit the water available for consumptive use in the West, may be triggered more often as a result of climate disruption. Changes in water supplies also may trigger water-use restrictions under interstate compacts. ? More droughts. Climate disruption could lead to more intense, frequent, and longer-lasting droughts in the interior West. More heat, less snowpack, less available water, and possibly more droughts are likely to lead to other changes across the West. Most significantly, wildfires are likely to increase in number and severity. http://www.arizonapirg.org/home/reports/report-archives/our-water-our-future/our-water-our-future/less-snow-less-water-climate-disruption-in-the-west Wed, 25 Jul 2007 14:52:35 -0500