Climate change in the U.S. Southwest

Joshua Tree National Park is located in Southern California. In California, over 3,000 native plant species are expected to

face reductions in hospitable geographic range. Image: pixabay/public domain.

Overview

The Southwest is the hottest and driest region in the nation. It extends from the Pacific Ocean

east to the Rocky Mountains and south to the Mexican border. It is home to about 56 million

people, about 90 percent of whom live in cities, including Albuquerque, Phoenix, Las Vegas,

Salt Lake City, Denver, San Diego, Los Angeles, Sacramento and San Francisco. The

population of the Southwest is expected to increase by nearly 70 percent by mid-century.

By U.S. Environmental Protection Agency, adapted by Newsela staff on 03.31.17

Word Count 1,076

Level 1210L

This article is available at 5 reading levels at https://newsela.com. 1

The Southwest encompasses a wide range of elevations, spanning valleys that are below sea

level to mountain ranges that contain some of the highest peaks in the United States. It spans

from deserts like the Mojave to the snowy Rocky Mountains and Sierra Nevada Mountains.

The Central Valley in California is one of the most productive agricultural regions in the

country.

Climate change is affecting the Southwest. Temperatures have increased by almost 2 degrees

Fahrenheit in the last century, with the 2001-2010 decade being the warmest since records

began 110 years ago. Average annual temperatures are projected to rise an additional 3.5

degrees to 9.5 degrees by the end of this century, with the greatest temperature increases

expected in the summer and fall. Drought conditions are already common in the Southwest

and drought periods are expected to become more frequent and more intense. Drought will

affect important water sources, including the Colorado River Basin. Combined with expected

population growth, climate change will make existing stresses worse.

Increased Competition For Water

A reliable water supply is crucial for sustaining people, agriculture, energy production and

ecosystems. The Southwest relies on the snow from mountains to melt slowly throughout the

spring and summer, when water demands are highest. This slowly melting snow is called

snowpack. Snowpack also helps keep the ground moist, which delays the onset of the fire

season and influences the prevalence and severity of wildfires. Over the last 50 years, there

has been less snow late in the winter and the snowpack has melted earlier.

In April 2015, the snowpack in California held only 5 percent of the water it typically holds at

that time of year, with some areas having no snowpack at all. This was the smallest April

snowpack in the last 65 years, and projections indicate continued declines in the future. In

addition to less snow accumulation, warmer temperatures are expected to speed snow

melting. Rain falling on snow could also result in more rapid runoff and flooding conditions in

spring.

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Rapid population growth will increase the competition for water, but increased temperatures

will mean more evaporation. This will leave reservoirs and rivers with less water.

Native Tribes Lose Reliable Drinking Water

The Southwest is home to 182 federally recognized tribes and communities. Native Americans

already face many challenges that will be made worse by climate change. These communities

face some of the highest poverty rates in the nation and often lack adequate food,

infrastructure, transportation and access to health and community services. Some

communities, including the Navajo Nation, are already experiencing the impacts of severe

droughts. Some shallow wells have run dry and have reduced drinking water supplies. There

have been reported losses of agricultural crops and livestock, as well as important medicinal

and cultural plants and animals. As climate change impacts worsen, Native American

populations will likely be limited in their ability to respond to increasing hardships, making

them especially vulnerable.

Health Problems Aggravated By Heat, Pollution

In the Southwest, more than 90 percent of the population live in cities. This is the highest

percentage of any U.S. region. Pavement and buildings retain heat, making cities warmer than

surrounding areas and driving residents’ vulnerability to heat-related illnesses. Heat stress is

the leading cause of weather-related death in the Southwest, with a greater number of deaths

expected as heat waves increase in number, length and intensity. Elderly populations and low

This article is available at 5 reading levels at https://newsela.com. 3

income households that may not have access to air conditioning are especially at risk from

heat stress. High temperatures also contribute to poor air quality, posing a risk to people with

asthma and other respiratory illnesses.

Health problems are expected to be further aggravated by disruptions to urban electricity and

water supplies. Greater energy use for cooling during heatwaves is likely to place additional

strain on the electric grid and could result in power outages.

Wildfires And Loss Of Plant Habitat

Projected increases in drought, wildfire, invasive species and pests will likely threaten native

forests and other ecosystems in the Southwest. Warmer, drier conditions have contributed to

an increase in the size of wildfires in recent decades. Fire is a natural occurrence in the

Southwest, but excessive wildfires destroy homes, transform ecosystems, threaten public

health and damage the economy. The 2003 Grand Prix fire in southern California alone

caused $1.2 billion in damages.

Approximately 40 percent of the region is estimated to be at risk of losing abundant plant

species. In California, over 3,000 native plant species are expected to face reductions in

hospitable geographic range. Iconic species, such as the Saguaro cactus in the Sonoran

Desert, are also threatened.

Crops Struggle Amid Water Reductions

California produces more than half the nation’s high-value specialty crops, including many

types of fruits, vegetables and nuts. Future production of these crops is likely to be affected by

both reduced water availability and rising temperatures. This will result in local economic

challenges and increasing food prices across the nation.

The majority of the Southwest utilizes irrigated croplands. As the population grows, more

freshwater may be diverted from irrigation use to urban areas. Warmer temperatures are likely

to cause crops to ripen and mature early, reducing some crop yields.

This article is available at 5 reading levels at https://newsela.com. 4

Livestock production in the Southwest is also expected to be affected by changes in water

availability and temperatures. Pasture lands are not irrigated, potentially reducing grazing

lands to drought. Meanwhile, warming temperatures impose additional stresses on livestock.

This article is available at 5 reading levels at https://newsela.com. 5

Quiz

1 According to the article, problems arising from infrastructure make dealing with climate change

more difficult.

Which sentence from the article BEST supports the idea outlined above?

(A) Temperatures have increased by almost 2 degrees in the last century, with the

2001-2010 decade being the warmest since records began 110 years ago.

(B) In April 2015, the snowpack in California held only 5 percent of the water it

typically holds at that time of year, with some areas having no snowpack at all.

(C) Pavement and buildings retain heat, making cities warmer than surrounding

areas and driving residents’ vulnerability to heat-related illnesses.

(D) Projected increases in drought, wildfire, invasive species and pests will likely

threaten native forests and other ecosystems in the Southwest.

2 Which of the following ideas is BEST supported by the section "Health Problems Aggravated By

Heat, Pollution"?

(A) Most people in the Southwest will be affected by rising temperatures in the

region's cities.

(B) Power outages will have a greater impact on Southwest cities than wildfires and

food shortages will.

(C) Elderly and low income populations are the only ones at risk for heat stress in

Southwest cities.

(D) High temperatures contribute to poor air quality in Southwest cities more than

air pollution does.

This article is available at 5 reading levels at https://newsela.com. 6

3 Read the sentence from the section "Native Tribes Lose Reliable Drinking Water."

There have been reported losses of agricultural crops and livestock,as well as important medicinal and cultural plants and animals.

How does the sentence contribute to the idea that Native Americans may be affected by climate

change in unique ways?

(A) It demonstrates that Native Americans are too impoverished to pay for

medicine.

(B) It illustrates how climate change might threaten Native Americans' culture as

well as their safety.

(C) It shows that Native Americans will have to change what they use in cultural

and medicinal practices.

(D) It explains to readers that Native Americans are more concerned about their

culture than their safety.

4 Read the paragraph from the section "Wildfires And Loss Of Plant Habitat."

Approximately 40 percent of the region is estimated to be at risk oflosing abundant plant species. In California, over 3,000 native plantspecies are expected to face reductions in hospitable geographicrange. Iconic species, such as the Saguaro cactus in the SonoranDesert, are also threatened.

What does this paragraph accomplish?

(A) It shows that California is at the greatest risk for climate change damage and

gives the readers a statistic to further illustrate that point.

(B) It helps readers understand that climate change, and specifically fires, will have

a greater impact on native plant species in the Southwest than it will on

humans.

(C) It introduces readers to the Saguaro cactus and evokes a sense of frustration in

the reader that more is not being done to protect this iconic plant.

(D) It gives an idea of the damage climate change will cause by detailing the

number of species impacted and naming one that readers might recognize.

This article is available at 5 reading levels at https://newsela.com. 7

Answer Key

1 According to the article, problems arising from infrastructure make dealing with climate change

more difficult.

Which sentence from the article BEST supports the idea outlined above?

(A) Temperatures have increased by almost 2 degrees in the last century, with the

2001-2010 decade being the warmest since records began 110 years ago.

(B) In April 2015, the snowpack in California held only 5 percent of the water it

typically holds at that time of year, with some areas having no snowpack at all.

(C) Pavement and buildings retain heat, making cities warmer than

surrounding areas and driving residents’ vulnerability to heat-related

illnesses.

(D) Projected increases in drought, wildfire, invasive species and pests will likely

threaten native forests and other ecosystems in the Southwest.

2 Which of the following ideas is BEST supported by the section "Health Problems Aggravated By

Heat, Pollution"?

(A) Most people in the Southwest will be affected by rising temperatures in

the region's cities.

(B) Power outages will have a greater impact on Southwest cities than wildfires and

food shortages will.

(C) Elderly and low income populations are the only ones at risk for heat stress in

Southwest cities.

(D) High temperatures contribute to poor air quality in Southwest cities more than

air pollution does.

This article is available at 5 reading levels at https://newsela.com. 8

3 Read the sentence from the section "Native Tribes Lose Reliable Drinking Water."

There have been reported losses of agricultural crops and livestock,as well as important medicinal and cultural plants and animals.

How does the sentence contribute to the idea that Native Americans may be affected by climate

change in unique ways?

(A) It demonstrates that Native Americans are too impoverished to pay for

medicine.

(B) It illustrates how climate change might threaten Native Americans'

culture as well as their safety.

(C) It shows that Native Americans will have to change what they use in cultural

and medicinal practices.

(D) It explains to readers that Native Americans are more concerned about their

culture than their safety.

4 Read the paragraph from the section "Wildfires And Loss Of Plant Habitat."

Approximately 40 percent of the region is estimated to be at risk oflosing abundant plant species. In California, over 3,000 native plantspecies are expected to face reductions in hospitable geographicrange. Iconic species, such as the Saguaro cactus in the SonoranDesert, are also threatened.

What does this paragraph accomplish?

(A) It shows that California is at the greatest risk for climate change damage and

gives the readers a statistic to further illustrate that point.

(B) It helps readers understand that climate change, and specifically fires, will have

a greater impact on native plant species in the Southwest than it will on

humans.

(C) It introduces readers to the Saguaro cactus and evokes a sense of frustration in

the reader that more is not being done to protect this iconic plant.

(D) It gives an idea of the damage climate change will cause by detailing

the number of species impacted and naming one that readers might

recognize.

This article is available at 5 reading levels at https://newsela.com. 9