Southwest

Climate Change Impacts

Arizona •Ÿ California •Ÿ Colorado Ÿ• Nevada Ÿ• New Mexico Ÿ• Utah

The following is a compilation of climate change impacts occurring right here, right now in the Southwest, as well as projected impacts, economic and human health consequences, and notable recent events. The Southwest is home to 56 million inhabitants and is the hottest and driest region in the United States. Climate change already poses a challenge to the Southwest, from extreme heat to sea level rise, and conditions are likely to increase in severity.

 


Extreme Heat

Right Here, Right Now

Figure: Projected temperature increases relative to a 1971-1999 baseline.

Temperature increases in the Southwest

Projected Trends

Economic Impacts

Impacts to Human Health and Wellbeing

  • Heat ranks among the deadliest of all natural hazards and is the leading weather-related cause of death in the U.S., with the highest rates of heat stress in Arizona. Rising temperatures and extreme heat will continue to increase the risk of heat stress.
  • Extreme heat threatens urban infrastructure and urban residents. At 92.7%, the Southwest has the highest percentage of people who live in cities relative to 80.7% nationwide. Nevada is even higher, at 94.2%. Increased heat can create a domino effect that impacts millions. For example, an 11-minute power disturbance in 2011 led to 1.5 million San Diego residents to lose power for 12 hours. The outage also caused problems with pumps and water service, leading to 1.9 million gallons of sewage being spilled near beaches.

Recent Events

Early 2014 California temperature anomalies

Figure: Early 2014 California temperature anomalies.


Extreme Precipitation

Right Here, Right Now

Projected Trends

Economic Impacts

Impacts to Human Health and Wellbeing

  • More frequent and intense precipitation contributes to increased flooding, which threatens infrastructure, homes, and lives. Warming also plays an important role as it results in wintertime precipitation falling as rain rather than snow.
  • September 2013 floods in Colorado resulted in multiple fatalities with an estimated 1,500 homes destroyed, and thousands more damaged in over 17 counties. 

Recent Events


Drought

Right Here, Right Now

  • The early 21st century drought in the Colorado River basin has been the most extreme in over a century of Colorado River flows and is linked to climate change. Models project more intense droughts in the Colorado River basin, with flow deficits that exceed any in the observational record by 60-70%.
  • Over the past 50 years, there has been less late-winter precipitation falling as snow, earlier snowmelt, and earlier arrival of most of the year’s streamflow.
  • Streamflow totals in the Sacramento-San Joaquin, the Colorado, the Rio Grande, and in the Great Basin were 5% to 37% lower between 2001 and 2010 than the 20th century average flow.

Projected

Snow water equivalent predictions

Economic Impacts

Impacts to Human Health and Wellbeing

Recent Events

 


Wildfires

Right Here, Right Now

Projected

Economic Impacts

  • More than 1.2 million homes—with a combined estimated value of more than $189 billion—across 13 western states are at high or very high risk of wildfires. The majority of the highest-risk properties are in California, Colorado, and Texas, which together have nearly 80% of such properties in the western states.
  • Total monetary costs associated with any wildfire are difficult to estimate but even partial costs can be staggering. A full accounting of wildfire costs considers long-term and complex costs, including impacts to watersheds, ecosystems, infrastructure, businesses, individuals and the local and national economy. The true costs of wildfire can be 2 to 30 times greater than the commonly reported costs of simply extinguishing the fire.
  • The 2003 Grand Prix fire in southern California cost $1.2 billion in damages, including $86 million in damages to roads, bridges, and electricity and gas infrastructure.
  • The June 2002 Rodeo-Chediski fire is the second largest fire in Arizona history, burning 462,614 acres. The costs of suppressing the fire were between $43 and $50 million, yet other direct costs, including the loss of homes and property, totaled $122.5 million. Rehabilitation costs were generated from immediate post-fire expenditures, and then projected out over three years for a total cost of $139 million. Indirect costs, including loss of sales tax revenue and job losses in the tribal community amounted to $8.1 million.
Rodeo-Chedeski Fire Costs
SUPPRESSIONOTHER DIRECTREHABILITATIONINDIRECTTOTAL
$46,500,000$122,500,000$139,000,000$403,000$308,403,000

 

Wildfire statistics

Impacts to Human Health and Wellbeing

  • Virtually every urban area in the Southwest has a large ring of homes in forested areas known as wildland-urban interfaces (WUIs). Persistent population growth has led to more homes and businesses being built in and near forested areas that are more prone to wildfires due to climate change.
  • Smoke from wildfires causes significant health problems, both when wildfires occur near major population centers and when smoke is carried long distances to populated areas. Aggravation of asthma and heart and lung diseases, breathing difficulties, and even death can result.
  • In June 2008, a California wildfire elevated levels of toxic particulate matter to concentrations greatly in excess of air quality standards. The values were among the highest ever reported.
  • The 2008 fire season in the Reno and Sparks area of Nevada led to almost $2.2 million in hospital costs caused by wildfires within a 350-mile radius.
  • study analyzing one month during southern California’s 2003 wildfire season found that wildfires resulted in 69 premature deaths, 778 hospitalizations, 1,431 emergency room visits, and 47,605 outpatient visits, mostly for respiratory and cardiovascular health problems aggravated by smoke exposure.

Recent Events

 


Sea Level Rise

Right Here, Right Now

Projected Trends

Sea level rise

Economic Impacts

Impacts to Human Health and Wellbeing

Recent Events