If a multi-day outage in Phoenix coincided with a heat wave, nearly half the population would need emergency care for heatstroke or other heat-related illnesses, a new study finds.
While Phoenix was the most extreme example, the study warned that other cities are also at risk. Since 2015, the number of major outages nationwide has more than doubled. At the same time, climate change is contributing to worsening heat waves and increasing instances of extreme weather around the world.
The study, published Tuesday in the journal Environmental Science and Technologysuggests the risk to cities would be compounded if a hurricane, cyberattack or windstorm were to knock out power during a heatwave and knock out thousands of air conditioners.
This summer, two-thirds of North America, including the Southwest, could experience power grid shortages, especially during periods of extreme heat when demand for air conditioning spikes, draining resources, according to analysis released this month. Phoenix Mayor Kate Gallego has urged the federal government to add extreme heat to the list of disasters such as floods and hurricanes that could result in a federal disaster declaration.
The new analysis found that Phoenix, which relies heavily on air conditioning to keep residents cool in the desert heat, would suffer immense loss of life and illness if a citywide power outage during a wave of heat lasted for two days, the power being gradually restored. the next three days.
In this scenario, about 789,600 people would need emergency care for heat-related illnesses, overwhelming the city’s hospital system, which has just 3,000 emergency beds, according to the study. An estimated 12,800 people in Phoenix would die, according to the study.
“I describe this as probably the greatest climate-related hazard we can imagine: a power outage during a heat wave,” said Brian Stone Jr.., the study’s lead author and a professor in the School of City and Regional Planning at the Georgia Institute of Technology.
To anticipate the effects of a prolonged power outage during oppressive heat, researchers modeled the temperatures residents of Atlanta, Detroit and Phoenix would be exposed to on an hourly basis, if the power was on. during a heat wave, and if not.
The researchers began by looking at past temperatures in these three cities. In Phoenix, they analyzed temperatures from a July 2006 heat wave, when the average high temperature was 113 degrees.
Then the researchers estimated what the temperature would be at hundreds of points across cities, not just at the airport, where temperature is usually measured.
They estimated the indoor temperatures of various residential buildings and used annual surveys collected by the US Department of Labor to model the time residents were likely to spend indoors and outdoors, based on their age, their gender, occupation and income. And the authors used census data to take into account the racial makeup of the three cities, Dr. Stone said.
In Atlanta, 11,600 people, or about 3% of the population, would need emergency care if a five-day heat wave coincided with a multi-day power outage, the team found. The city has only about 2,000 emergency room beds, and scientists estimated that six people in Atlanta would die during the twin crises.
The team, which also included researchers from Arizona State University and the University of Michigan, found that 216 people died during a heat wave and power outage in Detroit.
The researchers acknowledged some limitations in their findings. For example, their model assumed that people would stay put during a heat wave and power outage. In reality, the authors noted, some people would be able to move, and rescuers would attempt to evacuate residents and install generators in cooling centers.
Kristie L. EbiA professor at the University of Washington’s Center for Global Health and Environment, who was not involved in the research, called it a “pretty impressive study,” which should encourage cities to think about ways to protect vulnerable residents, including pregnant women, outdoor workers and people in historically demarcated communitieswhich have fewer trees and more pavement that retains heat.
David Hondula, a study author and that of Phoenix first director of heat response and mitigation, said that while officials there were deeply concerned about potential illnesses and deaths during a heat wave and power outage, “this is the first time we let’s see a number, and it’s obviously a pretty alarming number.”
According to the study, there are strategies that could help protect residents during outages and overlapping heat waves.
If cities planted enough trees to shade half their streetsdeaths would drop 14% in Atlanta, 19% in Detroit and 27% in Phoenix, according to the study.
What if they installed highly reflective “cold roofs” on each building, deaths would fall by 21% in Atlanta, 23% in Detroit and 66% in Phoenix.
But since climate change is expected to increase the frequency, duration and intensity of heat wavesthe study predicted that deaths and illnesses would increase even more.
Jane W. Baldwin, an assistant professor of earth system science at the University of California, Irvine, said the findings should underscore the importance of investing in a stronger power grid. This “would help prevent this terrifying compound risk in the present and will continue to pay off in the future as heat waves continue to worsen,” Dr Baldwin said.