Arizona's climate has changed over the centuries. The ancient native peoples began farming the area in approximately 1500 B.c.E., and optimum rainfall increased arable farmland and drew a larger population. A Medieval climate anomaly in the southwest during the 8th and 12th centuries caused hardship.
While climate models vary on the amount of temperature increase possible with unmitigated global warming, Arizona's temperature could increase as much as 6.75 degrees F (3.75 degrees C) by the end of the century. The potential risks include: decreased water supplies from decreased snow pack in the mountains, thereby reducing summer flow in Arizona streams; increased risk for wildfires; changes in food production as temperatures rise beyond the tolerance level of crops; more extreme fluctuations in precipitation levels across the region (heavier rainfall and flooding events in winter, and summer drought conditions); change in rain pattern to downpours with the potential for flash flooding; and health risks of certain infectious diseases from water contamination; disease-carrying vectors such as mosquitoes, ticks, and rodents; and heat-related illnesses. The recent drought and intense wildfire seasons in Arizona are consistent with what climatologists expect will occur more frequently as global warming continues. A study by an Arizona and New Mexico team examined charcoal residues of ancient forest fires. During colder climate periods, smaller, less damaging fires occurred and during warmer climate periods, severe, standclearing fires occurred. Based on these data, global warming may cause more severe forest fires.
Based on energy consumption data from the U.S. Energy Information Association in 2007, Arizona's total CO2 emissions from fossil fuel combustion in 2004 was 96.16 million metric tons of CO2, made up of contributions from: commercial 2.04, industrial 4.62, residential 2.20, transportation 36.07, and electric power 51.22. Arizona committed to lowering its greenhouse gas emissions to 2000 levels by 2020, and 50 percent below 2000 levels by 2050. Arizona instituted a requirement that 1.1 percent of the state's energy come from renewable sources by the end of 2007.
In February 2005, Arizona established the Climate Change Advisory Group. Arizona holds member status with the Western Regional Climate Action Initiative, in which the partners will set an overall regional goal for reducing greenhouse gas emissions and design a market-based mechanism to help achieve that reduction goal.
Arizona joined the Climate Registry, a voluntary national initiative to track, verify, and report greenhouse gas emissions, with acceptance of data from state agencies, corporations, and educational institutions beginning in January 2008. The state's solar energy program issues a tax credit to individuals for installing a solar or wind energy device at an Arizona residence.
SEE ALSO: Alternative Energy, Solar; Deserts.
BIBLIOGRAPHY. Mark Bowen, Thin Ice Unlocking the Secrets of Climate in the World's Highest Mountains (Henry Holt, 2005); A.N. Garwood, Weather America: Latest Detailed Climatological Data for Over 4,000 Places and Rankings (Toucan Valley Publications, 1996); National Wildlife Federation, "Global Warming and Arizona," http://www.nwf. org/globalwarming/pdfs/Arizona.pdf (June 19, 2007).
Lyn Michaud Independent Scholar
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