As immense as climate change sounds, its impacts will be experienced locally. What kinds of climatic changes could we expect on the Colorado Plateau?  Climate models reveal serious challenges ahead for the region.

The U.S. National Assessment of the Potential Consequences of Climate Variability and Change (2000) is the best resource available on the subject. As part of the national process, a Southwest sub-report was published in September 2000 predicting hotter average temperatures and heavier winter rains. Average temperatures could increase as much as 5ºF by 2030, and 7-12ºF by 2090.  Likely impacts by sector include:

Water – Model scenarios suggest increased winter rainfall for the Colorado Plateau over the next century. This could elevate water supplies, but those benefits could be partially or entirely offset by increased evaporative loss in water delivery systems and rising demand from a growing population. In addition, heavy winter rains may cause flooding, accelerate soil erosion, and pose greater risks to property and life. Snowpack in places like the San Francisco Peaks is likely to be reduced even if overall precipitation increases. Earlier and more rapid snowpack melting would contribute to flooding and a shorter ski season.

Ranching – In general, more rain would enhance natural vegetation for areas like the Kane and Two Mile Ranches and enable ranchers to expand cattle stocks or graze the same number of animals on less land. However, the timing of precipitation is critical – increased winter rains could run off too early to affect the spring growing season, and have no impact on growth associated with summer monsoons. Furthermore, increased climate variability is projected for the region, meaning greater frequency of very wet and very dry years. This would make range management and planning more difficult. Years with less rain could increase costs of supplemental feed, water hauling, and cattle relocation, and risk further damage to rangeland ecosystems.

Natural ecosystems – Changes in temperature, water availability, and atmospheric carbon dioxide could significantly alter Colorado Plateau ecosystems, from the ponderosa forests to the Colorado River. Human development has inhibited the ability of natural ecosystems to adapt by fragmenting habitats, introducing invasive species like tamarisk and cheat grass, and creating migration barriers like Glen Canyon Dam. Some species will be able to migrate to higher elevations in the mountains. Depending on the pace and degree of climatic changes, alpine ecosystems could disappear from the region. More frequent El Niño events are likely to increase vegetation growth that could fuel forest fires in drier years.

Mining – More rainfall would increase the likelihood of overflow containing highly toxic chemical and metal pollutants from storage reservoirs and holding ponds. Future climate policies aimed at reducing carbon dioxide emissions could have an indirect negative effect on coal mining if electricity generators shift to lower-carbon fuels.

Human health – Climate changes could increase the incidence of Hantavirus and allow the spread of infectious diseases like dengue fever, encephalitis, and valley fever in the region. Heat-related illnesses also could increase. The region’s population is growing rapidly, with the heat susceptible elderly population accounting for the largest percent increase.

Urban areas – Increased flooding could further stress urban infrastructure such as St. George’s drainage channel system, as well as sewage systems, pipelines, and roadways. Air quality could be negatively impacted as temperatures rise, and the “urban heat island” effect could be exacerbated in cities. 

Energy – Currently, 7 new coal-fired, greenhouse gas emitting power plants are proposed for the Colorado Plateau. More new power plants will probably be needed to meet demand associated with higher temperatures and a growing population.  Any future climate policy is likely to result in additional costs and operational changes for the electricity sector, which is a major emitter of greenhouse gasses. 

Clearly, society will need the will and flexibility to make many adaptive changes as our grand, unwitting experiment with the earth’s climate unfolds over the next century.

Links to other Climate Change sites

National Parks Conservation Association

Clear the Air

Clear the Air/Water in the West

RealClimate

Climate Hot Map

Apollo Alliance

Union of Concerned Scientists

Green House Network

United Nations Framework Convention on Climate Change

Arizona Climate Change Advisory Group