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Phoenix's heat is rising — and so is the danger

During the hottest week of the year in America's hottest big city, 10 people died of heat-related causes.

Another nine people died the following week in metro Phoenix, as June gave way to July, and authorities suspect heat may have contributed to an additional 27 deaths over those two weeks.

The average temperature in Phoenix in that period was 113 degrees, peaking at 119 on June 20, the day of the summer solstice. On four days, the temperature never dropped below 90 degrees, even in the dead of night.

By the first day of fall, Arizona's notorious heat had contributed to more than 60 deaths in Maricopa County and was suspected in 119 more since the start of 2017.

As bad as that sounds, the years ahead look bleaker unless Arizonans find ways to adapt their urban environment to a warming world and make the vulnerable safer.

“There’s going to be more extreme heat waves — and there already are extreme heat waves,” said Daniel Swain, a University of California, Los Angeles, climate scientist.

Unlike the intensity of any given hurricane or wildfire, he said, there’s no debating the nuances of climate change’s effect on the thermometer. Hotter is hotter.

Slight changes in yearly average temperatures, like the 2 degrees that the broader Southwest already has experienced, can lead to killer temperature spikes in the hot months.

“If 115 is the new norm,” Swain said, “what’s the hottest day (like)?”

Arizona climate researchers expect Phoenix's all-time high of 122 degrees to look more like the typical yearly high later this century, and they say the city could see a new record over 130 degrees to rival Death Valley's world mark.

Already, the city's hot season — when temperatures exceed 100 degrees — starts an average of almost three weeks earlier than it did 100 years ago and lasts two to three weeks longer in the fall.

The threat has grown all too real. In 2016, 150 people in metro Phoenix died of heat-related causes, the largest annual number since agencies started counting. So many deaths from one apparent cause would count as a natural disaster if they occurred all at once.

Texas officials said Hurricane Harvey, which swamped the state in August and September, killed about 80 people. Wildfires in Northern California killed more than 40 people by mid-October. Both events led national headlines for weeks.

Yet the deadly heat doesn't grip the country's attention, and its victims often die anonymously.

One explanation: It plays out over time. Rather than one deadly landfall or firestorm, heat kills a few people a week, for months on end.

Also: Heat is often an indirect killer. In many cases, it exacerbates a chronic condition that leads to a death. But heat is a killer just the same — in cooler temperatures, some of those people might have lived.

And heat kills the people the rest of the world tends to notice least.

Many of its victims live in poorer neighborhoods that lack shade and cooling grasses. Some, lacking the money for an air-conditioner, have only old-style evaporative coolers, or no home cooling at all. Others have air-conditioners but not the cash to pay hundreds of dollars a month to run them in summer.

As temperatures rise, Phoenix's widening concrete expanses soak up and hold heat into the night, heaping more stress on those same vulnerable residents whose health and housing protect them the least.

The rest of the desert city, made livable in the summer by chilled indoor air and lush outdoor landscaping, will watch the heat fade into the cool of fall, largely without noticing that those who have the least suffer the most.

'If it's just hot, it's fine'

Emma Cordova lives on the other side of the divide, with no air-conditioner.

The 70-year-old neighborhood activist from Sherman Park has complained for decades that Phoenix should plant and maintain more than the few trees that grow in a park strip under the power-line corridor that faces her home.

Interstate 17 cooks the air at the west end of her block, and rock cover at her end of the park strip absorbs heat, as do a row of warehouses with asphalt lots a block to the north.

Studies have shown that in neighborhoods like hers in south Phoenix, with little tree cover, temperatures average as much as 8 degrees hotter in summer than in lusher districts where residents with bigger water bills enjoy 25 percent tree coverage.

“If it’s just hot, it’s fine,” Cordova said between sips of bottled water on her family's sofa in July, acknowledging the city’s proverbial dry heat. “But when it’s humid out, it’s hard here.”

The midsummer monsoon had turned the air damp, straining the evaporative action in the swamp cooler she uses to avoid paying for air-conditioning.

It was 89 degrees inside.

“I can turn it higher,” she said, “but it just blows warm air.”

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Many people like her may have an air-conditioner but little money to turn it up. For one-quarter of households in metro Phoenix, the cost of electricity is a barrier to properly cooling their homes, according to a 2015 Maricopa County Public Health assessment of community heat vulnerability. One-tenth of those surveyed said they “always” or “most of the time” feel hot in their homes.

Most were unaware of utility-assistance programs or cooling stations that open during extreme heat warnings.

About one-quarter of households also reported having at least one member who works outdoors, usually during day shifts.

Many heat victims are older and sicker, naturally vulnerable. Some don’t have a car or just think they can move about as normal. They over-exert themselves before they recognize heat exhaustion or, eventually, heat stroke.

Eventually, some will die. Maricopa County has tracked heat-related deaths for about a decade, and the numbers have risen sharply in recent years until 2016's peak at 150. In 2017 the final figures may climb even higher: So far, the county has either confirmed or is investigating 183 suspected heat deaths.

Hot and getting hotter

The stress is likely to intensify throughout this century.

Climate researchers can't pin individual deaths on climate change, especially given personal variables like health and home or work environment. Instead, much as scientists say climate change increases the odds of intense storms in any given year, the warming stokes conditions that can lead to more danger.

Days when temperatures climb past 110 degrees or so bring an exponentially greater risk, said Diana Petitti, a clinical professor at the University of Arizona College of Medicine-Phoenix.

“If we have more 115-degree days over time without some kind of public-health response or some mitigation response,” she said, “we can expect to have more heat-related illness and death.”

Phoenix posted temperatures of 115 degrees or higher six times in June and July of this year. By comparison, in the 75 years from 1896 to 1970, there were 60 years when the city never reached 115 degrees at all.

Days spent at 110 or higher double the incidence of death in metro Phoenix. Maricopa County averaged about 1.3 deaths per day at such temperatures from 2010 to 2016, according to data from the county's Department of Public Health. There were 0.6 deaths per day when the high ranged from 100 to 109.

As temperatures in Phoenix climb, so do the number of deadly days. The city's all-time average is 12 days a year at 110 degrees or hotter, but the National Weather Service says recent warming pushed the 1981-2010 average to 18 days.

This summer, the temperature reached or exceeded 110 degrees on 25 days, and for 11 consecutive days in June. That stretch peaked on June 20 at 119 degrees.

The problem is gaining attention among urban planners and public-health experts in central Arizona, where cities and their non-profit partners foresee a mitigation push. Those efforts are only beginning. Phoenix plans a massive tree-planting campaign, and groups like the Nature Conservancy are working with university researchers to envision cooler landscapes for neighborhoods with vulnerable residents.

“We face quality-of-life issues, and we face economic issues,” Nature Conservancy urban program manager Maggie Messerschmidt said. “That’s if we don’t address it. That’s if we put our heads in the sand.”

Arizona rightly talks a lot about its skills at managing water for future growth, but rarely about managing heat through smarter growth, she said.

June 20: the hottest day

On the hottest day of the year, two cyclists sprawled under a tree, sweating, panting and shielding a kitten from the blazing sun.

Jose Ruiz was helping his friend, Tina Granados, escape a bad relationship. She clutched the one belonging that mattered, a tiny black-and-orange kitten she called Meow-Meow. They had biked 5 miles to the grassy park west of Phoenix’s central library and were nearing Ruiz’s neighborhood when Meow-Meow had enough.

“We were doing so good till she decided to jump and burned her paws” on the hot Culver Street blacktop, Granados said.

A Salvation Army crew spotted them and insisted they take some iced water bottles, one of which Granados dumped on the scowling cat.

Ruiz and Granados gulped the water and rolled along so Ruiz could drop his friend at his apartment and bike to work at a nearby McDonald’s.

“Feels like it’s 105!” Ruiz said before swinging back onto his bike.

He was surprised to learn that the National Weather Service had already posted a temperature of 115 degrees at Sky Harbor International Airport. The day would top out at 119 degrees, within 3 degrees of the city’s hottest day ever.

June 20 represented an extreme for 2017, but likely not for long.

The last completed decade — 2001-2010 — was the region’s warmest in 110 years of record-keeping. It was 2 degrees Fahrenheit warmer than historic averages. That's 2 degrees averaged over the course of a year, and that can lead to much higher daytime spikes on the hottest days of the year.

Dozens of daily records have fallen in the city this decade, three in that June week alone.

Almost a third of Phoenix’s days now bake at 100 degrees or hotter each year. During the last 20 years, the city has endured on average 5 ½ weeks more of those triple-digit days than it had in the same span a century earlier. On average, the temperature now reaches 100 degrees early in May and the last 100-degree day of the year is increasingly edging into October.

The 2014 National Climate Assessment’s Southwest chapter, compiled by University of Arizona climate experts, projected up to 5.5 degrees more warming by the mid-century period and 9.5 degrees before 2100 if carbon emissions continue increasing.

Those projections don’t account for urban heat retention — the much-discussed heat-island effect — which already warms Phoenix nights well beyond the surrounding desert’s.

The quest for cool

For many Arizonans, May through October is hot only when they step outside.

It isn’t so simple for those who lack air-conditioning, work outdoors or have nowhere to go during the day.

“The heat is brutal,” 57-year-old William Butler said after stopping in for lunch this summer at a downtown Phoenix center for homeless seniors. “It’s the heavyweight champion of the world: no losses.”

He recalled a spate of heat deaths in 2007, the first of his sporadic years among the homeless after a surgery and temporary paralysis.

Butler described his summer days as a series of movements from one shady spot or cool building to the next, from otherwise pointless rides on Valley Metro light-rail cars to daily workouts and showers at the downtown YMCA. He lives on Social Security disability payments and has slept at a shelter since falling behind on his $650 monthly rent early this summer.

He carries a water bottle and fills it at no cost at convenience stores, keeping hydrated until the shelter reopens in evening.

“Seems like the last eight years it’s getting hotter and hotter and hotter,” Butler said. “The heat just drains you.”

Stuck on a heat island

The nights can wear on a body when urban “heat islands” — concrete and asphalt expanses that soak up daytime sun — keep temperatures at 90 or hotter.

Left unaltered, the desert releases much of its heat when the sun sets, a cycle still evident outside the urban areas.

Arizona State University scientists compared Phoenix with the rural farm hub of Sacaton, just to the metro area’s southeast. They charted changes in average temperatures — blending highs and lows — through the June-August season to demonstrate how concrete and asphalt have warmed the city.

They also tracked day-night temperature spreads to show how the urban environment is slower to return solar radiation into space.

Sacaton’s average summer temperature was 86 in 1948 and 90 in 2011, ASU researcher Matei Georgescu determined. The average day-to-night difference was virtually unchanged in both periods, around 33 degrees.

During the same span in Phoenix, the city warmed up on average from a starting point of 88 degrees to 95, and the day-night gap shrank from 29 degrees to 22. Rising low temperatures accounted for much of the change in the seasonal average.

“It’s becoming much more common during the monsoon for (Phoenix) temperatures to not dip below 90 degrees,” Georgescu said.

Before 1970, Phoenix recorded only two such sultry nights — both during the 1930s Dust Bowl era, according to National Weather Service records. Since then, 90-degree nights have become a virtual certainty, usually scattered across weeks of summer.

Maricopa County Public Health's data showed a spike from 1 death per day when nighttime lows are in the upper-80s to 1.8 when they top 90.

Georgescu's team modeled a worst-case Phoenix based on Maricopa County Association of Governments growth projections made before the Great Recession slowed construction. The team tested the model against past warming from urbanization. They found that piling in millions more people and the buildings and roads to support them could warm the city on average another 7 degrees by 2050, without accounting for any global climate change.

That assumes the buildings don’t have reflective “cool roofs,” that most people continue driving cars routinely, and that Arizona sprawls in its customary pattern.

“All of these things play an important role,” Georgescu said.

More extreme extremes

While urbanization works on the nights, climate change heats the days.

Scientists at ASU's Urban Resilience to Extremes Sustainability Research Network, working with peers around the country, project blazing-long summers for Phoenix.

ASU climate scientist Nancy Grimm shared unpublished data tracking a so-called “business as usual,” continuing escalation in the burning of fossil fuels, and it points to vastly more extreme-heat days. Network colleagues at North Carolina State University ran models that portend months more in the danger zone.

The team plans to publish the results for Phoenix and nine other cities, possibly in conjunction with the next congressionally mandated National Climate Assessment.

The scientists project a late-21st century with 91 days at or above 110 degrees in Phoenix, 42 of them eclipsing 115.

Using a more optimistic emissions standard, in which global carbon output stabilizes and begins falling after 2040, the models project an average of 51 days above 110 and 13 above 115.

The team also estimates that unchecked greenhouse gas increases would push the city’s average hottest day to 123, from its historic average of 113. The outlying record breaker, replacing 1990’s brush with 122, could top 130.

Relief made in the shade

There are ways of preparing.

Studies contrasting temperatures in shaded and bare Phoenix neighborhoods suggest that targeted landscape planting could protect many residents from global warming's worst.

Phoenix has a goal to double its tree canopy to shade 25 percent of the surface. This year’s city budget funds 1,000 plantings, though it will take more than a decade to reach the goal, and most of the trees will necessarily be on private lands. Neighborhoods that reach the goal can effectively compensate for expected heat gains through the middle of the century.

Planting trees to combat urban heat-island effect
One tree at a time, the city of Phoenix is trying to increase its shade canopy to 25 percent by the year 2030. David Wallace/

Cool roofs — those that reflect most of the sun’s rays — can reduce urbanization’s warming effects by up to half, according to Georgescu’s ASU heat-island research. The exact effect depends on the building’s size, as air moving over the tops of single-family houses affects ground temperatures, but air moving over taller buildings doesn’t.

The Nature Conservancy’s new program partners with Maricopa County Public Health, ASU researchers, the Central Arizona Conservation Alliance and others to plan a remake for three metro neighborhoods. One is in south Phoenix, one east of downtown, and one in Mesa — all in zones that the partners determined were hotter than their surroundings and housed vulnerable residents with a lower percentage of homes with air-conditioning.

The program has a $125,000 grant from the Vitalyst Health Foundation.

They will attempt to tailor natural cooling systems such as green space, shaded bus stops, storm-water retention for watering new trees and permeable pavements and soils to absorb rainfall and later evaporate it to cool the air.

For now, though, much of Phoenix bakes hotter than it must.

'Slowly cooking': Aug. 10

Homeless men filed into the Justa Center in sparsely vegetated southwestern downtown Phoenix one August morning to get help with job postings, housing prospects or birth certificate requests — anything to ease them off the streets.

The center for homeless seniors is only open in the mornings. For the late afternoon that would soon reach 105 degrees, they were on their own. Horst Feuerriegel, a 74-year-old German amputee, was among them, soon to be wheeling his chair “anywhere in the shade.”

He dreaded the evening’s slow lineup to get back into an overnight shelter. “You’re slowly cooking,” he said. “It’s a mess. You’re surrounded by dope.”

Phoenix had reached 111 degrees the previous day.

Feuerriegel had made a life as a trucker in Colorado but got stranded on Phoenix’s streets when a medical emergency struck while he was returning from a San Diego vacation. He had stepped on something during his trip — a tin can, he thinks — and was limping badly with gangrene when he stopped in Eloy. An ambulance took him to a Phoenix hospital, where he lost his left leg.

He had never meant to stop in the desert, but now he needed to stay as cool as possible until he could leave in the coming weeks.

The staff at the Justa Center helped him get approved for German retirement benefits, and he was waiting for the first installment so he could return to family in Europe.

He worried about the heat’s effect on a heart condition he has.

“I know it’s bad for me,” he said. “I’m not used to it.

“I’m glad to be going home.”

Unmitigated heat threatens to become an economic drag on metro Phoenix if the region suffers more deaths and hospitalizations, less worker productivity, and fewer creative workers willing to move to the desert, the Nature Conservancy’s Messerschmidt said.

The region must invest more in community comfort, she said, especially in its poorest and hottest quarters.

“This is our workforce that lives in these spaces,” she said. “This is an issue that affects everyone.”

PART 2: How heat discriminates
PART 3: The human cost of heat, and those who paid
The human cost of heat: 30 stories

Environmental coverage on and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow The Republic environmental reporting team at OurGrandAZ on Facebook, Twitter and Instagram.