Long Blackouts Are Up to 50 Times More Likely in Parts of the U.S.

Not all power outages in the U.S. are created the same. Populations that are already socially vulnerable are being exposed in some areas to high levels of threatening blackouts—while climate change is making long power outages much more likely, according to new research published in Nature Communications.

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A power outage that lasts just a few minutes can be an inconvenience, but one that goes on for hours can be deadly. People who rely on medical equipment like ventilators, oxygen machines, and home dialysis are threatened by every additional hour without electricity; during an intense heat wave or serious winter storm, not being able to turn on your air conditioner or electric heat could be life-threatening. As our planet continues to warm and storms and heat waves get more intense, our electric grid is also feeling the strain: reports of weather-related power outages between 2011 and 2021 were 78% higher than in the previous decade, according to the nonprofit Climate Central.

It’s clear that we need a better understanding of how climate change is impacting our electricity supply. But data and reports on power outages can often be unhelpful in illustrating which communities exactly are affected. An intense storm may barrage several states, but what is the exact breakdown in terms of which populations are affected the most by weather-related power outages?

“No one has produced information on power outages at the hourly and county level across the United States before,” Joan Casey, an environmental epidemiologist at the University of Washington and one of the authors of the study, told Earther in an email.

In order to get a better understanding of how power outages in the U.S. manifest for specific populations, the researchers used data on outages spanning 2018 to 2020, collected from PowerOutages.us. That website pulls information from utility websites on customers without power. Of the 3,142 counties in the U.S., they were able to obtain data for 2,447 of them, representing nearly three-quarters of the total population. (There are some obvious gaps in the data, especially in rural Western states: nearly 100% of Montanan counties and over 90% of Alaskan counties were missing, as well as nearly three-quarters of Utah.)

In analyzing the data, the researchers found that a lot of Americans are going through long stretches without power. During that two-year period, more than 70% of the counties surveyed experienced a power outage that lasted more than eight hours at least once. Those lengthy outages tended to happen more often in the late spring and mid-summer, and tended to peak when people were at home and using their electricity the most, in the late afternoon and early evening. They also had a geographic trend: clusters of regions in the South (especially Louisiana), the Northeast (Maine and upstate New York), and Appalachia had particularly intense pockets of counties where long outages were common.

The authors also wanted to dig into who was being affected by outages in these regions. They used a variety of socioeconomic indicators—including racial and ethnic minority statistics, Medicare data, percentage of a county living below the poverty level, and the number of people living in mobile homes—to identify counties that were particularly vulnerable and experiencing power outages. In this analysis, they found that clusters of counties in Louisiana, Arkansas, central Alabama, and northern Michigan where people were both socially vulnerable and experiencing high levels of intense power outages.

Then there’s the climate aspect. The researchers took the data on those super-long outages and overlaid it with information on climate-related weather disasters in each county during the same time period, including storms, heavy winds, and heat waves. Those weather disasters made serious outages a lot more common. Tropical cyclones—a storm categorized by high winds and intense precipitation—made long outages almost 14 times more common. And days when there were at least two weather events happening at once—a storm and an intense heat wave, for instance—made the likelihood of a long outage a shocking 50 times more likely.

“This speaks to the need to prepare for a future with a more uncertain climate and an aging electric grid,” Casey said.

There are many possible next steps with this research that would help suss out who is being affected and why by climate change and blackouts. Outages, after all, don’t happen in a vacuum; for most of us, electricity is delivered to our homes by powerful utilities, many of which have notoriously dropped the ball during weather disasters in recent years. How are county-level outages like the ones analyzed in this research impacted by whoever is in charge of delivering the electricity? How are people in socially vulnerable counties being served—or not—by their electricity provider, and how is that set to change with the energy transition?

That question, Casey said, was beyond the scope of this work. But this research illustrates a solid correlation between extreme weather and life-threatening outages, and opens the door for a lot more questioning.

“Power outages in the U.S. occur in most counties, and their frequency and duration will likely increase with climate change and an aging electric grid,” Casey said. “Therefore, we need to understand if and how these outages may affect health, how we can prevent them, and how we can target interventions to upgrade the grid and move to renewable energy in communities that would benefit the most.”