78 | Rolling Stone | September 2019
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Disease Control and Prevention, between 2004
and 2017, about a quarter of all weather-related
deaths were caused by excessive heat, far more
than other natural disasters such as hurricanes
and tornadoes.
Still, the multiplying risks of extreme heat
are just beginning to be understood, even in
places like Phoenix, one of the hottest big cit-
ies in America. To Mikhail Chester, the direc-
tor of the Metis Center for Infrastructure and
Sustainable Engineering at Arizona State Uni-
versity, the risk of a heat-driven catastrophe in-
creases every year. “What will the Hurricane Ka-
trina of extreme heat look like?” he wonders
aloud as we sit in a cafe near the ASU campus.
Katrina, which hit New Orleans in 2005, result-
ing in nearly 2,000 deaths and more than $100
billion in economic damage, demonstrated just
how unprepared a city can be for extreme cli-
mate events.
“Hurricane Katrina caused a cascading failure
of urban infrastructure in New Orleans that no
one really predicted,” Chester explains. “Levees
broke. People were stranded. Rescue operations
failed. Extreme heat could lead to a similar cas-
cading failure in Phoenix, exposing vulnerabil-
ities and weaknesses in the region’s infrastruc-
ture that are difficult to foresee.”
In Chester’s view, a Phoenix heat catastro-
phe begins with a blackout. It could be triggered
any number of ways. During periods of extreme
heat, power demand surges, straining the sys-
tem. Inevitably, something will fail. A wildfire
will knock out a power line. A substation willwhen the temperature soars to 115°F or higher,
heat becomes a lethal force. Sunshine assaults
you, forcing you to seek cover. The air feels
solid, a hazy, ozone-soaked curtain of heat. You
feel it radiating up from the parking lot through
your shoes. Metal bus stops become convection
ovens. Flights may be delayed at Sky Harbor
International Airport because the planes can’t
get enough lift in the thin, hot air. At City Hall,
where the entrance to the building is embla-
zoned with a giant metallic emblem of the sun,
workers eat lunch in the lobby rather than trek
through the heat to nearby restaurants. On the
outskirts of the city, power lines sag and buzz,
overloaded with electrons as the demand for air
conditioning soars and the entire grid is pushed
to the limit. In an Arizona heat wave, electrici-
ty is not a convenience, it is a tool for survival.
As the mercury rises, people die. The home-
less cook to death on hot sidewalks. Older folks,
their bodies unable to cope with the metabolic
stress of extreme heat, suffer heart attacks and
strokes. Hikers collapse from dehydration. As
the climate warms, heat waves are growing lon-
ger, hotter, and more frequent. Since the 1960s,
the average number of annual heat waves in 50
major American cities has tripled. They are also
becoming more deadly. Last year, there were
181 heat-related deaths in Arizona’s Maricopa
County, nearly three times the number from
four years earlier. According to the Centers for
blow. A hacker might crash the grid. In 2011, a
utility worker doing routine maintenance near
Yuma knocked out a 500-kilovolt power line that
shut off power to millions of people for up to 12
hours, including virtually the entire city of San
Diego, causing economic losses of $100 million.
A major blackout in Phoenix could easily cost
much more, says Chester.
But it’s not just about money. When the city
goes dark, the order and convenience of mod-
ern life begin to fray. Without air conditioning,
temperatures in homes and office buildings
soar. (Ironically, new, energy-efficient build-
ings are tightly sealed, making them dangerous
heat traps.) Traffic signals go out. Highways grid-
lock with people fleeing the city. Without power,
gas pumps don’t work, leaving vehicles strand-
ed with empty tanks. Water pipes crack from
the heat, and water pumps fail, leaving people
scrounging for fresh water. Hospitals overflow
with people suffering from heat exhaustion and
heatstroke. If there are wildfires, the air will be-
come hazy and difficult to breathe. If a blackout
during extreme heat continues for long, rioting,
looting, and arson could begin.
And people will start dying. How many? “Ka-
trina-like numbers,” Chester predicts. Which is
to say, thousands. Chester describes all this cool-
ly, as if a Phoenix heat apocalypse is a matter of
fact, not hypothesis.
“How likely is this to happen?” I ask.
“It’s more a question of when,” Chester says,
“not if.”E
XTREME HEAT IS the most direct,
tangible, and deadly consequence
of our hellbent consumption of
fossil fuels. Rising carbon- dioxide
levels in the atmosphere trap heat,
which is fundamentally changing
our climate system. “Think of the Earth’s tem-
perature as a bell curve,” says Penn State climate
scientist Michael Mann. “Climate change is shift-
ing the bell curve toward the hotter end of the
temperature scale, making extreme-heat events
more likely.” As the temperature rises, ice sheets
are melting, seas are rising, hurricanes are get-
ting more intense, rainfall patterns are chang-
ing (witness the recent flooding in the Midwest).
Drought and flooding inflict tremendous eco-
nomic damage and create political chaos, but
extreme heat is much more likely to kill you di-
rectly. The World Health Organization predicts
heat stress linked to the climate crisis will cause
38,000 extra deaths a year worldwide between
2030 and 2050. A recent study published in Na-
ture Climate Change found that by 2100, if emis-
sions continue to grow, 74 percent of the world’s
population will be exposed to heat waves hot
enough to kill. “The more warming you have, the
more heat waves you have,” says Michael Weh-
ner, a scientist at Lawrence Berkeley National
Laboratory. “The more heat waves you have, the
more people die. It’s a pretty simple equation.”
Heat waves are driven not just by rising tem-
peratures but by a change in the dynamics ofOn a
scorching
day in
downtown
Phoenix,
Contributing editor JEFF GOODELL wrote about
the Paris Agreement in January.