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Southwest Regional Climate Change
California, Nevada, Arizona, Utah, Colorado and New Mexico
Information from the U.S. Global Change Research Program, June, 2009
Rising Temperature and Water Shortage
The southwest region includes the states of California, Nevada, Arizona,
Utah, New Mexico and portions of Colorado and Texas. This region has
experienced a more rapid rate of warming than any other region of the United
States. Much of the spring stream flow here is a result of melting snow
packs in the mountains. However, warmer winters have reduced the snow pack
and that now reduces stream discharge in the spring.
The southwest has the most rapid population growth in the United States. Growing
cities contribute to the urban heat island effect which will exacerbate the
impact of rising temperatures - especially during the summer months.
The southwest has been in a water supply crisis for decades. High usage
rates and a growing population have caused a significant depletion of ground
water resources and overuse of surface water resources. Increasing
temperatures will cause higher evaporation rates and reduce the amount of
water available for stream flow and ground water recharge. Climate change
will cause water challenges in the southwest to become much more difficult
in the years ahead.
| Recreation Opportunities Likely To Suffer |
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Unique tourism and recreation opportunities are likely to suffer.
Rising temperatures will adversely affect winter activities such as downhill and cross-country skiing, snowshoeing, and snowmobiling. Later snow and less snow coverage are projected for ski resort areas, particularly those in the southern part of the region. Decreases from 40 to almost 90 percent are likely in end-of-season snowpack under high emissions scenarios in counties with major ski resorts from New Mexico to California. Photo copyright by iStockPhoto / A. Solovei. |
| Rising Temperature = Less Agricultural Land |
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Increasing temperature, drought, wildfire, and invasive species will accelerate transformation of the landscape.
Impacts of climate change on the landscape of the Southwest are likely to be substantial, threatening biological diversity, protected areas, and ranching and agricultural lands. Temperature increases have made the current drought in the region more severe than the natural droughts of the last several centuries. Record-setting wildfires are resulting from the rising temperatures and related reductions in spring snowpack and soil moisture. Photo copyright by iStockPhoto / J. Wynn. |
| Everyone Loses When Water Is Scarce |
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Water supplies will become increasingly scarce, calling for trade-offs among competing uses, and potentially leading to conflict.
Water is vital to agriculture, hydroelectric power production, the growing human population, and ecosystems. Water supplies in some areas are already becoming limited. Large reductions in spring precipitation are projected for the Southwest. Continued temperature increases combined with river flow reductions and rapid population growth will increase competition for water supplies. Photo copyright by iStockPhoto / C. Spencer. |
| Projected Spring Precipitation Change |
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Percentage change in March-April-May precipitation for 2080-2099 compared to
1961-1979 for a lower emissions scenario (left) and a higher emissions scenario
(right). Confidence in the projected changes is highest in the hatched areas. |
| Observed and Projected Temperature Rise |
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Percentage change in March-April-May precipitation for 2080-2099 compared to
1961-1979 for a lower emissions scenario (left) and a higher emissions scenario
(right). Confidence in the projected changes is highest in the hatched areas. |
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| Climate change will have a number of severe impacts on the southwestern states of California, Nevada, Arizona, Utah, Colorado and New Mexico. This page illustrates a number of the more significant impacts. Map by Geology.com and MapResources. |
| Heat Waves May Cause Electric Blackouts |
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Cities and agriculture face increasing risks from a changing climate.
With more intense, longer-lasting heat waves projected to occur over this century, demands for air conditioning are expected to deplete electricity supplies, increasing risks of brownouts and blackouts. Much of the region's agriculture will experience detrimental impacts in a warmer future, particularly specialty crops in California such as apricots, almonds, artichokes, figs, kiwis, olives, and walnuts. These and other such crops require a minimum number of hours below a chilling temperature threshold in the winter to set fruit for the following year. Photo copyright by iStockPhoto / J. DeLillo. |
| Flood Buffers Lost Due to Vegetation Die-Off |
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Increased frequency and altered timing of flooding will increase risks to people, ecosystems, and infrastructure.
Rapid landscape transformation due to vegetation die-off, wildfire, and loss of wetlands along rivers reduces flood-buffering capacity. Decreased snow cover on the lower slopes of high mountains and the increased fraction of winter precipitation falling as rain and therefore running off more rapidly also increases flood risk. Photo copyright by iStockPhoto / T. Campbell. |
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