Climate change in Arizona

Climate change in Arizona encompasses the effects of climate change, attributed to man-made increases in atmospheric carbon dioxide, in the U.S. state of Arizona.

Köppen climate types in Arizona show a preponderance of arid and desert environments.

It has been asserted that Arizona "will suffer more than most of U.S." due to climate change.[1] According to the United States Environmental Protection Agency, Arizona "has warmed about two degrees (F) in the last century. Throughout the southwestern United States, heat waves are becoming more common, and snow is melting earlier in spring. In the coming decades, changing the climate is likely to decrease the flow of water in the Colorado River, threaten the health of livestock, increase the frequency and intensity of wildfires, and convert some rangelands to desert".[2]

Environmental impacts

Snowpack

"As the climate warms, less precipitation falls as snow, and more snow melts during the winter. That decreases snowpack—the amount of snow that accumulates over the winter. Since the 1950s, the snowpack has been decreasing in Arizona, as well as most mountainous areas in the Colorado River Basin. Diminishing snowpack can decrease water supplies and shorten the season for skiing and other forms of winter tourism and recreation".[2]

Water availability

"The changing climate is likely to increase the need for water but reduce the supply. Rising temperatures increase the rate at which water evaporates (or transpires) into the air from soils, plants, and surface waters. Irrigated farmland would thus need more water. But less water is likely to be available, because precipitation is unlikely to increase enough to make up for the additional water lost to evaporation. Annual precipitation has decreased in Arizona during the last century, and it may continue to decrease. So soils are likely to be drier, and periods without rain are likely to become longer, making droughts more severe".[2]

"The decline in snowpack could further limit the supply of water for some purposes. Mountain snowpacks are natural reservoirs. They collect the snow that falls during winter and release water when the snow melts during spring and summer. Over the past 50 years, the snowpack throughout the Colorado River Basin has been melting earlier in the year (see map on back page). Dams capture most meltwater and retain it for use later in the year. But upstream of these reservoirs, less water is available during droughts for ecosystems, fish, water-based recreation, and landowners who draw water directly from a flowing river".[2]

Wildfires and changing landscapes

"Higher temperatures and drought are likely to increase the severity, frequency, and extent of wildfires, which could harm property, livelihoods, and human health. On average, more than 2 percent of the land in Arizona has burned per decade since 1984. Wildfire smoke can reduce air quality and increase medical visits for chest pains, respiratory problems, and heart problems".[2]

"The combination of more fires and drier conditions may expand deserts and otherwise change parts of Arizona’s landscape. Many plants and animals living in arid lands are already near the limits of what they can tolerate. A warmer and drier climate would generally extend the Sonoran and Chihuahuan deserts to higher elevations and expand their geographic ranges. In some cases, native vegetation may persist and delay or prevent expansion of the desert. In other cases, fires or livestock grazing may accelerate the conversion of grassland to desert in response to a changing climate. For similar reasons, some forests may change to desert or grassland".[2]

Pests

"Warmer and drier conditions make forests more susceptible to pests. Drought reduces the ability of trees to mount a defense against attacks from pests such as bark beetles, which have infested 100,000 acres in Arizona. Temperature controls the life cycle and winter mortality rates of many pests. With higher winter temperatures, some pests can persist year-round, and new pests and diseases may become established".[2]

Economic and social impacts

Agriculture

"Increasing droughts and higher temperatures are likely to affect Arizona's top agricultural products: cattle, dairy, and vegetables. Hot temperatures threaten cows’ health and cause them to eat less, grow more slowly, and produce less milk. Livestock operations could also be impaired by fire, the lack of water, and changes in the landscape from grassland to woody shrubs more typical of a desert. Reduced availability of water would also create challenges for irrigated farms, which account for two-thirds of the water used in the state".[2]

Tribal communities

"Changing the climate threatens natural resources and public health of tribal communities. Rising temperatures and increasing drought are likely to decrease the availability of certain fish, game, and wild plants on which the Navajo and other tribes have relied for generations. Water may be less available for domestic consumption, especially for those who are not served by either municipal systems or reliable wells, which includes about 30 percent of the people on the Navajo Nation, who must haul water to meet daily needs. Recurring drought and rising temperatures may degrade the land itself. In the Navajo Nation, for example, the Great Falls Dune Field has advanced almost a mile in the last 60 years, threatening roads, homes, and grazing areas. Extreme heat may also create health problems for those without electricity, including about 40 percent of the people on the Navajo reservation".[2]

See also

References
  1. Loomis, Brandon (June 30, 2017). "Arizona will suffer more than most of U.S. as climate changes, study says". The Arizona Republic.
  2. "What Climate Change Means for Arizona" (PDF). United States Environmental Protection Agency. August 2016.

Further reading
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