D.C. residents faced scorching sidewalks and sunburned shoulders last weekend as temperatures climbed near 100 degrees. And while lingering summer heat remains commonplace in the DMV region, large swaths of the northern hemisphere are experiencing major heat waves in recent weeks.
But if you’re wondering if this heat wave has anything to do with climate change, the short answer is yes, absolutely.
Dr. David Keellings, a researcher at the University of Florida who focuses on how climate change impacts extreme weather events, said the long answer remains slightly more complicated.
“It’s a very nuanced thing because we can’t really say that climate change caused any one particular extreme event to happen,” Keellings said. “But what we can say is that climate change is making these events more likely.”
Heat waves are stretches of time, at least two days, where temperatures rise above what’s normal in a given region. For D.C. and the rest of the Northeast, at least three days in a row above 90 degrees typically qualify as a heat wave, according to AccuWeather senior meteorologist Alex Sosnowski. The District hit that mark for more than six days straight last week while the heat index, which takes humidity into account to describe how hot it feels outside, reached 104 degrees on July 24.
Even the seemingly small increase in global temperatures caused by greenhouse gases – less than 2 degrees Fahrenheit – can greatly increase the likelihood and severity of extreme heat events.
To explain why, Keellings compared it to what happens when a teacher curves the score on a class exam. If a teacher adds two points to every exam, the average student’s grade will be a little higher but so will the A+ students’ grades. But if anyone got 100% to begin with, they’ll now have 102% — a score that wasn’t even possible before. Similarly, as average temperatures across the whole planet rise, “normal” heatwaves will happen more frequently and some parts of the world will experience new, record-breaking temperatures.
“An event that was perhaps only likely to happen every few hundred years in the past suddenly becomes an event that’s going to happen every few decades, or every decade,” Keellings said.
While the whole planet is experiencing climate change, the rising temperatures will not impact everyone equally. Manmade materials like concrete, asphalt, steel and glass trap heat in cities, causing what’s known as the urban heat island effect.
“If I was to walk from a rural location in towards the city center and then towards the central business district, it would get hotter and hotter and hotter,” Keellings said.
Within the District, some neighborhoods, particularly those without sufficient tree cover and green space like parks, will get hit especially hard. Last year, Washington City Paper, in collaboration with nonprofit Hola Cultura, found that some neighborhoods in wards 1, 2, and 5 can end up 10 to 20 degrees hotter than the parts of the leafiest areas in wards 2 and 3.
Even on the individual level, extreme heat doesn’t impact everyone equally. Underlying housing and income inequalities put Black, Latino and Native American people at particular risk of hospitalization or death due to heat emergencies, according to Nambi Ndugga and Samantha Artiga, policy specialists at the Kaiser Family Foundation.
CDC data shows that, compared to white people, racial and ethnic minorities in the U.S. experience higher rates of diabetes, hypertension, obesity, asthma and heart disease – all of which increase the risk of heat stroke.
That exacerbation of inequalities that already exist, Keellings said, is a feature of climate change that will only get worse and more widespread if global leaders in all sectors do not act fast to cut emissions and increase resiliency.
“When I think about climate change, in general, one of the most concerning things is that it’s going to continually expand inequality globally,” he said. “Each year, we’re going to see the increased probability of having these really extreme events. But within society, we have groups of people that are much more vulnerable.”