The IPCC report has a chapter on the Southwest, and it’s brutal

By: - August 20, 2021 8:18 pm
housing vista

(Photo: Ronda Churchill)

Drought, wildfires, declining water supplies, threats to human health made even more dangerous by urban design flaws and socioeconomic inequities — the climate crisis has already hit the Southwest hard. And it’s only going to get worse.

That’s the message in the chapter on the U.S. Southwest in the latest report from  the Intergovernmental Panel on Climate Change, which anticipates global temperatures will pass the 1.5 degrees Celsius threshold needed to avert permanent climate disaster as soon as the early 2030s. That means more drought, more fire, more heat, more illness and more trouble for the Southwest.

Global warming has already triggered changes that will persist even if the emissions stop and temperatures stabilize. However, if emissions are greatly reduced it may be possible to bring down global temperatures after crossing that threshold by the end of the century.

The report comes from the first of three working groups to release their findings in a 4,000-page document written by more than 200 authors examining and researching the latest science on climate change.

Nevada has already experienced the repercussions of climate change addressed in the report through a combination of warming, wildfires and drought that has affected water supplies and air quality in the state this year.

On Monday, the federal government officially declared the first-ever water shortage in the Colorado River Basin, leading to mandatory water cuts for Nevada in 2022. Under the cuts, Nevada will lose about 7% of its allocation, or 21,000 acre-feet of water. 

Air quality gains have been reversed in the last few years due to an increase in wildfires across the West that have affected the state.

Matthew Lachniet, a professor at UNLV, studies paleoclimatology, which uses natural records to paint pictures of Earth’s past climate. His most recent research took him to a cave in the southern Great Basin, in central Nevada, where ancient climate records show a glimpse of what severe drought looks like for the Southwest and the Colorado River Basin. During one 4,000 year-period in the ancient past, the Southwest sustained hot, dry and arid conditions which were linked to warm Arctic seas, a lack of sea ice, and warming in the western tropical Pacific Ocean.

“We don’t expect there to be any sort of natural cycle that will tip us back into wet periods,” said Lachniet “Not anytime in the next couple centuries.”

“Current policy is out of sync with nature because the policies allow for the withdrawal of more water from the Colorado River than what’s being provided by nature. We just can’t sustain it in the long term,” said Lachniet.

The Fourth National Climate Assessment is broken down into national-level topics and regional chapters, giving a clear view of how climate change will hit the Southwest, including Nevada.

Hotter and dryer

Temperatures in the Southwest have increased 1.6 degrees Fahrenheit  from 1901 to 2016.

An increase in evaporation due to higher temperatures will make it harder for rain to replenish soil moisture and surface water making the desert environment even drier, a potentially permanent change.

Under a worst-case scenario, the annual average Southwest temperature could increase by 8.6°F by 2100. Nevada and other regions in the Southwest could get up to 45 more days each year with maximum temperatures of 90°F or higher. 

Human-caused climate change will lead to more water scarcity in the Southwest.

Since 2000, drought that was intensified by long-term trends of higher temperatures due to climate change has reduced the flow in the Colorado River (top left), which in turn has reduced the combined contents of Lakes Powell and Mead to the lowest level since both lakes were first filled (top right). In the Upper Colorado River Basin that feeds the reservoirs, temperatures have increased (bottom left), which increases plant water use and evaporation, reducing lake inflows and contents. Although annual precipitation (bottom right) has been variable without a long-term trend, there has been a recent decline in precipitation that exacerbates the drought. (IPCC description and graphics)

Drought, demands from a growing population, and dropping groundwater levels, are putting more stress on the Southwest’s already strapped water supplies. Higher temperatures have significantly altered the water cycle, evidenced by less snow, shorter snowfall seasons, earlier runoff, and late-season stream temperatures, all resulting in less water making it to the Colorado River Basin. 

Since 2000, Lake Mead on the Colorado River has fallen 130 feet and lost 60% of its volume, a result of the ongoing Colorado River Basin drought and continued water withdrawals by cities and agriculture.

Reductions in runoff are also increasing the salinity of Pyramid Lake in Nevada, reducing fish biodiversity and affecting the cui-ui fish, the primary cultural resource of the Pyramid Lake Paiute Tribe.

And as water levels on the river have fallen, the population in the Southwest has grown. The Southwest is home to 60 million people, with the total population growing 30% faster than the national average.

“No matter what happens, even if we get periods where it’s a little wetter than has been in the last two decades, then we’re still going to be dealing with a water shortfall because temperatures have increased,” said Lachniet. “We need to plan for that new reality, and not only plan for that new reality but acknowledge that warming is going to continue increasing until we reduce carbon concentrations in the atmosphere.”

Fires and toxins

Climate change is increasing the frequency and intensity of wildfires, and making air quality worse.

The disrupted climate has led to an increase in the area burned by wildfire in the west. Analyses estimate that the area burned by wildfire from 1984 to 2015 was twice what would have burned had climate change not occurred. Furthermore, the area burned from 1916 to 2003 was more closely related to climate factors than to fire suppression, local fire management, or other non-climate factors.

The cumulative forest area burned by wildfires has greatly increased between 1984 and 2015, with analyses estimating that the area burned by wildfire across the western United States over that period was twice what would have burned had climate change not occurred. (IPCC description and graphics)

Ecosystems can naturally slow climate change by storing carbon, but due to recent wildfires,  forests are releasing more carbon to the atmosphere than they are storing. Wildfire has damaged habitat and exacerbated the spread of invasive plant species. Repeated wildfire in sagebrush in Nevada has caused extensive invasions of cheatgrass, reducing habitat for the sage-grouse, which is not listed under the Endangered Species Act despite a population drop of as much as 80 percent since 1965.

Under continued higher carbon emissions, fire frequency could increase 25%, and the frequency of very large fires and area burned could triple in the Sierra Nevada by 2100, while under a lower emissions scenario, fire would only slightly increase.

Wildfires increase ground-level ozone and produce toxic pollutants which are released into the air. More intense wildfires have also led to more buildings and homes being destroyed which only exacerbates toxic pollutants, including lead. 

In sickness and in death

Human health in the Southwest is projected to deteriorate.

More heat-associated deaths and illnesses, increased vulnerabilities to chronic disease, and other human health risks resulting from extreme heat will confront residents of the Southwest, according to the report. Combined exposure to ground-level ozone pollution — some of it generated by wildfires — particulate air pollution, respiratory allergens, and extreme heat worsens respiratory and cardiovascular disease.

Mortality risk during a heat wave is amplified on days with high levels of ground-level ozone or particulate air pollution, with the greatest mortality due to cardiovascular causes.

Under higher emissions, the Southwest would experience the country’s highest increase in annual premature deaths due to extreme heat, with an estimated 850 additional deaths per year and an economic loss of $11 billion by 2050. Under lower emissions , deaths and costs would be reduced by half, compared to the higher scenario.

Studies have shown that mental health would also suffer under extreme climate change. Chronic stress brought by poverty has proven to lessen people’s ability to cope with additional stress. Populations living in poverty also have lower economic resilience to adapt to extreme changes. 

Rural and agricultural communities would be hit hardest by mental health effects due to loss of livelihood and livable communities. In the Southwest, which has the largest population of Indigenous peoples in the country, tribal communities could face the loss of traditional foods and cultural resources as drought and wildfires increase leading to lowered mental health. Historically, Indigenous peoples in the Southwest have been forcibly restricted to lands with limited water and resources.

Action — and inaction

The IPPC report’s focus on the Southwest ends by inventorying some local and regional efforts to adapt to and mitigate the impacts of the climate crisis. For example, Nevada has  placed a major emphasis on water conservation and clean energy development. Nevada has made moves to grow roof-top solar in the state, and lawmakers have directed NV Energy to spend $100 million to expand electric vehicle charging infrastructure over the next three years, 40% of which must go to “historically underserved communities.”

However, climate policy experts say more needs to be done to protect people from climate change.

“States need to confront their climate crisis,” said Noah Long, director of the Western Region Climate and Clean Energy Program for the Natural Resources Defense Council. “It’s critical that states implement changes and that they do it comprehensively. Responsibility lies with states to protect their citizens from the worst effect of climate change.”

Climate scientists agree that government officials at both the federal and local level must step up plans to mitigate the environmental, health and safety threats that will only intensify in the Southwest. Full-scale implementation of adaptation planning will require significantly more resources, say scientists.

The IPPC recommends increasing “adaptive capacity,” the ability for systems to adjust to, respond to, and recover from climate impacts. That includes policies ranging from emergency services planning  and urban designs that are climate-conscious, to The IPPC recommends increasing “adaptive capacity,” which can range from emergency services and urban designs that are climate-conscious, to alleviating poverty and confronting socioeconomic inequities that will be deepened and intensified by hotter, dryer and more toxic conditions.

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Jeniffer Solis
Jeniffer Solis

Jeniffer was born and raised in Las Vegas, Nevada where she attended the University of Nevada, Las Vegas before graduating in 2017 with a B.A in Journalism and Media Studies.