Climate change is hurting Arizonans' health, U.S. report says

A new federal climate report says increases in extreme heat, flooding, drought and wildfires “are negatively impacting the health of Southwest residents,” including Southern Arizonans.

In Pima County, one of those factors, extreme heat, took a heavy toll on human life this year. During the scorching summer, as more than 50 daily and monthly high temperature records were broken, the number of heat-caused deaths — 43 — was the highest in at least 12 years, Medical Examiner’s Office records show.

The incidence of Valley fever, a common respiratory disease in Arizona that can be fatal, has increased sharply during the 21st century, the National Climate Assessment’s newest report also finds.

And it says rising temperatures and other impacts of human-caused climate change continue to stress the Southwest’s long-burdened water supplies, threaten future crop production, and increase wildfire risks. Climate change also has triggered large-scale marine heatwaves and harmful algae blooms that “have caused profound and cascading impacts on marine coastal ecosystems and economies,” the report said.

But as it released this grim report on Nov. 14, the Biden administration sought to offer a little hope as well. It announced it will make available $6 billion to help communities in the Southwest and nationally respond and adapt to climate change impacts.

The targeted programs include modernizing and strengthening the country’s electric grid, advancing environmental justice efforts, improving the ability of ecosystems to withstand climate change and reducing flood risks. Most of the money will come from the 2021 Bipartisan Infrastructure Act and the 2022 Inflation Reduction Act.

The climate reports were mandated by the U.S. Global Change Research Act of 1990. Among other things, each “analyzes the effects of global change on the natural environment, agriculture, energy production and use, land and water resources, transportation, human health and welfare, human social systems, and biological diversity.”

They also analyze current trends in global environmental change and look ahead to trends over the next 25 to 100 years. This year’s, the fifth report, again contains a chapter devoted to Southwestern climate change impacts.

Heat-caused deaths

In Pima County, the county Medical Examiner’s Office recorded 125 heat-related deaths this year, for which heat exposure was at least a contributing factor.

The 43 heat-caused deaths were determined by the office to have been caused by direct exposure to Tucson’s extreme summer heat or to dehydration stemming from the heat.

These figures don’t include heat-caused and heat-related deaths sustained by migrants making their way through the Sonoran Desert after crossing the border. Including those deaths in Pima and all such deaths in two other Southern Arizona counties, the totals rise to 128 deaths caused by heat exposure and 225 heat-related deaths, medical examiner’s records show.

The office only began tabulating heat-related deaths, as a category beyond heat-caused deaths, this year. But this year’s 43 heat-caused deaths in Pima County are at least four times more than documented in all but two years since 2011, a Medical Examiner’s report shows. Last year, the county recorded 28 heat-caused deaths, but in most years since 2011, the total number barely reached or exceeded 10.

Looking strictly at deaths for border-crossers this year, the Medical Examiner’s Office has recorded 50 heat-related migrant deaths in Pima County and 68 when including Cochise and Santa Cruz counties.

The rate of Pima County’s heat-related deaths of 11.7 per 100,000 residents in 2023 approached that of Maricopa County, the fastest-growing and hottest major metropolitan area in the U.S. Maricopa County has recorded 579 heat-related deaths this year, almost five times the number here.

Besides Phoenix’s more intense heat, another factor is that Maricopa County has far more residents — about 4.6 million — than Pima County’s total of about 1.06 million. “It’s just based on scale,” said Pima County Medical Examiner Greg Hess.

Maricopa County has documented 12.5 heat-related deaths per 100,000 residents so far this year. That rate could rise because the county is investigating another 56 deaths as possibly heat-related. Pima County has no more such deaths under investigation.

Increasing Valley fever

Considering the entire Southwest, the new National Climate Assessment report found when it comes to public health:

The sharp increase in the incidence of Valley fever, a common respiratory disease in the Southwest, especially Arizona and California, is “associated” with warmer air temperatures and drier soils.

But “a combination of several factors, not just climate factors” lies behind that increase, said John Galgiani, a University of Arizona professor and director of UA’s Valley Fever Center for Excellence. They include the migration of more people into Pima, Maricopa and Pinal counties, the aging of the population in regions where the disease has long existed, changes in reporting of the disease and increased testing for it, he told the Star.

Climate-related disasters such as droughts, floods and other storm-related incidents caused more than 700 fatalities in 31 disaster events in this region since 2018.

Strong evidence indicates extreme heat disproportionately affects the health of frontline and overburdened communities, including the unhoused, outdoor workers, migrant farmworkers, low-income people and older adults.

Between 2016 and 2020, 7,687 hospitalizations occurred in the Southwest due to heat-related illnesses, up from 5,517 in the previous five years.

Limited occupational health and safety standards for farmworkers and other outdoor workers are of “key concern,” as intensifying wildfires and heat collide with harvest seasons each year, particularly for undocumented Hispanic and Indigenous migrants.

“The improvement of these standards at the state and national levels will be critical for health adaptation to climate impacts in the region,” the report said. “Moreover, the harm to farmworkers due to wildfire smoke is expected to be greater than previously thought.”

Climate migrants arriving

The report finds with “medium confidence” that climate change is shaping the region’s demographics, spurring human migration from Central America to the Southwest.

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“The effects of climate change on other regions of the world — especially Central America — are changing the Southwest’s demographics,” it said.

Decreasing agricultural productivity, increasing food insecurity levels, and adverse climate effects are among the main reasons people emigrate from the Northern Triangle countries of Guatemala, Honduras and El Salvador to the U.S., said the report. It cited studies on the impact of Central American hurricanes and of how food issues caused residents to flee those three countries.

“In 2021, 42% of Central American immigrants to the U.S. lived in the Southwest region, and about 43% of immigrants apprehended at the Southwest border in 2019 originated from the Northern Triangle.

“Many are poor, women, children, or indigenous peoples. Climate-related migration has been shown to affect people’s physical and mental health, resulting from exposure to weather extremes, disruption of social ties, and overcrowding of health systems in the host communities,” the report said.

Farming will get tougher

Continuing drought and water scarcity will make it more difficult to raise food and fiber in the Southwest without major shifts to new strategies and technologies, the report says, adding that it has “high confidence” in that projection.

The study’s authors also place “high confidence” in their view that “Extreme heat events will increase animal stress and reduce crop quality and yield, thereby resulting in widespread economic impacts.”

Yet the report also expresses “medium confidence” in the view that the Southwest’s millennia-old history of adapting to drought impacts, “incorporating Indigenous knowledge with technological innovation can offer solutions to protect food security and sovereignty.”

“Across the Southwest, annual average minimum air temperatures, growing degree days, and average number of days above 86°F are projected to increase due to climate change,” it said. “By midcentury under intermediate and very high scenarios, projections show longer growing seasons, a northward shift in plant hardiness zones, and expanded areas of heat stress exposure to crops and livestock.”

Farmers and ranchers are particularly at risk from prolonged, severe drought, said the report.

“Future temperature increases are expected to drive higher rates of evapotranspiration, increasing demand for fresh water for irrigation. The producers most vulnerable to local precipitation deficits are dryland farmers growing rain-fed crops and producers raising livestock on rangelands.”

“Under increasing aridity, agricultural practices such as fallowing and grazing on rangelands will need careful management to avoid increased wind erosion and dust production from exposed soils. Rising summer temperatures also degrade protective desert soil crusts formed by communities of algae, bacteria, lichens, fungi, or mosses, adding to airborne dust loads.”

These factors make aridity a double whammy for agriculture, as dust deposits on mountain snowpack drive faster melting, depleting the snowpack, and result in reduced surface water for irrigation.

“Climate change poses risks to both productivity and quality of fruit and vegetable products, requiring adaptations on farms and throughout the supply chain.”

Those include changes in crop calendars, nutrient and pest management strategies, post-harvest handling, and preservation methods, the report said.

“The cascading impacts of climate change in combination with urban population increases and other social and cultural factors pose an increasing threat to agriculture in the region,” the report said. “Urban growth in the Southwest has led to competition for water between farms and cities, mirroring global trends. Water transfers from rural to urban areas have been a feature of the Southwest for decades, often with negative consequences for rural and low-income communities.”

Low-income urban communities are expected to be among the first to suffer food insecurity as climate change reduces the region’s food production, the report said. Strategies have been proposed to produce more food in urban settings, but these foods often do not reach low-income consumers, the report said. That’s because they have less access to food distribution systems and often cannot afford to pay the higher prices such foods often command.

Groundwater supply risks

The impacts to the Colorado River, Tucson’s main drinking water supply, that are documented in the report have been well known for years. It said, for instance, that between 1913 and 2017, average annual river flows dropped 9.35% for each 1.8 degree Fahrenheit temperature increase.

Less well known is that warming weather threatens groundwater supplies. That’s because it will reduce groundwater recharge from rainfall, snowmelt, and runoff in some areas, the report said.

“These effects are exacerbated by groundwater pumping to satisfy the needs of agricultural irrigation, which is the biggest consumer of fresh water in the region. Excessive groundwater pumping compared to recharge, for instance, has made California’s Central Valley aquifer of California one of the most stressed aquifers in the world,” the report said.

Also, flooding from extreme precipitation events and snowmelt conditions poses a threat to life, property and freshwater ecosystems, it said.

Due to climate change, snowmelt-driven flooding is expected to occur earlier in the year due to earlier runoff. As the climate warms, atmospheric rivers, which have driven much of historical flooding in the region, are expected to intensify.

Atmospheric rivers are relatively long, narrow regions in the atmosphere — like rivers in the sky — that transport most of the water vapor outside of the tropics, says the National Oceanic and Atmospheric Administration. The average atmospheric river carries an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River, NOAA says.

Like with many other climate change impacts, slashing of water supplies often disproportionately affects Indigenous communities and other lower-income groups, the report said.

One reason COVID-19 spread 3.5 times faster in Indigenous communities than the nation as a whole during the pandemic’s initial stages, it said, was a lack of clean drinking water in some of these communities.

A major obstacle to water access in some tribal communities is the cost of water infrastructure. Navajo families who must haul their water pay $43,000 an acre-foot, compared to an average of $600 an acre-foot for non-Indigenous communities who rely on piped drinking water, said the report. An acre-foot is enough to serve about four Tucson families for a year.

Furthermore, many tribes in the region continue to lack access to water because their water rights have not been adjudicated through settlements or other processes, although the Tohono O’odham, Pascua Yaqui, Ak-Chin and Gila River Indian Communities in Southern and Central Arizona have had at least some of their water rights settled in legal proceedings.