In the West, as much as 70 percent of the region’s precipitation falls during winter. Arizona and New Mexico are critically dependant on this winter precipitation. The region’s two main water lifelines, the Colorado River and the Rio Grande, tap the winter snows in the Rocky Mountains for approximately 70 percent of their annual water flow. (Read more)

Current observations suggest that climate change is altering streamflows in ways that negatively impact water supply for southwestern populations. Many climate models suggest that these changes will worsen as the climate warms, accentuating the natural variability inherent in river flows.

Since water is one of the most vital resources in the arid Southwest, the consequences of reduced streamflows and changes in the timing of peak river flows will impact water consumption, agriculture production, economic growth, recreation opportunities, and electricity generation, among other vital services. (Find out more)

Groundwater provides drinking water to urban and rural communities and supports agriculture and industry, all of which have helped enable rapid population growth in Arizona and New Mexico. Population expansion, however, has not been without its consequences. It has led to increasing groundwater withdrawals that are outpacing the rate at which the vital resource is naturally replenished. As a result, the region’s groundwater resources are among the most overused in the United States (continue reading). 

Health risks are linked to climate change through direct and indirect cause-and-effect chains, and depend on factors such as a person’s age, health condition, economic status, access to quality healthcare programs, and exposure to the elements. In the Southwest, regional health risks linked to climate change include extreme heat conditions, poor air quality, and increased food-, water-, fungal- and animal-borne diseases (Read More).

In the Southwest, climate is an important natural resource and a draw for tourists. Many people come to the region to take advantage of its warm, mild winters, to boat or kayak in the lakes and rivers, or to enjoy snow sports in the higher elevations.

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​An invasive species is a plant, animal, or microbe that adversely affects the native ecosystem upon introduction to a new community. Invasive species are well-adapted to encroach upon new territory, and invaders compete with native species for resources like water and soil nutrients. Many invasive species are so well-adapted to diverse conditions that they can outcompete their native counterparts, leading to environmental damage and decreased biodiversity. Regional impacts of climate change, including warmer temperatures, decreased precipitation, and increased levels of carbon dioxide will affect how and where invasive species migrate and colonize (Read more).

Despite the Southwest’s arid climate, rivers in the region are not immune to overflowing their banks and flooding city streets, farms, and desert. Climate change likely will increase both flash floods and regional floods, making the region’s growing population more susceptible to losses of life and property. How climate change alters future floods remains an open-ended question. However, recent observations and research are contributing to a better understanding of flooding in the Southwest (read more).

Water is a critical natural resource for people in the arid Southwest, as the region is highly susceptible to drought. Climate change impacts on southwest drought could thus have profound implications for society. Global climate projections indicate the future holds higher annual temperatures and less winter precipitation for the Southwest. These warmer temperatures may intensify the impact of drought on residents of the Southwest: recent research links the regional drought that peaked in intensity in summer 2002 (Figure 1) with more severe impacts on water, land, and people, than previous, drier droughts, due to warmer temperatures (read more). 

In the Southwest, normal changes in seasonal climate make the landscape ripe for fires. Every winter, precipitation spurs plant growth, while the dry months of April, May, and June turn the vegetation into tinder. At the time in which the landscape is most primed for fire, convective monsoon storms generate lightning, providing the match. Add in fire suppression by federal agencies, population growth that increases numbers of campfires and careless people, and human-caused climate change and the relationship between fire and climate becomes complicated (read more).

Drought deeply affects the land, water, and people of the Southwest. It occurs when precipitation averages fall below the norm. A drought can persist for many years, punctuated by particularly severe dry stretches and sometimes a relatively rainy year. The cloudless skies associated with drought not only imply below-average rainfall, but also an increase in the amount of direct sunlight hitting the ground, which leads to higher evaporation rates.

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