You have climate change to thank for this year’s scorching NYC summer

Climate change contributed to about four weeks’ worth of sweaty, sweltering weather in New York City between June and August, according to a new study by the climate science nonprofit Climate Central.

Global warming also quadrupled the odds of this month’s unusual late-summer heat wave, the research found.

“The heat that hit New York City around Labor Day had a very significant climate fingerprint,” said Andrew Pershing, who leads research efforts at Climate Central.

And it isn’t a one-off, either: “Those sorts of conditions are the ones that we need to prepare for” going forward, he added.

Extreme heat is on the rise nationwide due to greenhouse gas emissions from the combustion of fossil fuels. But it’s especially dangerous in urban areas like New York City, where dense buildings and wide swaths of pavement make hot days feel even hotter. And the combination of the two can be deadly. Dangerously high temperatures kill hundreds of New Yorkers each year, and city data shows that Black New Yorkers are disproportionately affected.

For the new study, researchers used historical data to create two models: one with a climate like our own, and another hypothetical model for a world without human-caused climate change. (Sounds nice!) Then, they compared the probability of each hot day this past summer between the two models. The larger the gap between the probabilities, the more likely that climate change affected that day’s weather.

Climate Central found that between June and August, New Yorkers endured 28 scorching days so statistically improbable that they were likely influenced by climate change. That puts the New York metro area among the cities most affected by climate change in the Northeast region, according to the data.

But these counts are nothing next to the sweltering temperatures seen in southern states. In Texas, Louisiana and Florida, climate change affected months’ worth of weather, data from Climate Central shows. Austin, Texas, experienced more than 45 days above 100 degrees Fahrenheit before the end of August. Meanwhile, Mobile, Alabama, broke a 152-year-old record for summer temperatures.

New York City’s September heat wave, however, put the five boroughs back on the extreme weather map. The 90-plus degree temperatures were extremely uncommon in September, according to the climate change-free model the researchers made. The data shows that climate change has quadrupled the odds of such conditions during back-to-school season.

“It's really surprising to feel such intense temperatures after the peak of summer, and that makes them all the more likely to be enhanced by climate change,” said Samuel Bartusek, a doctoral candidate at Columbia University’s Lamont-Doherty Earth Observatory who wasn’t involved in the work. Bartusek praised the researchers’ estimates for including both historical observations and statistical models, which make them more reliable than those that rely on just one data source.

That unseasonable heat can be dangerous for vulnerable New Yorkers, including children, older adults, outdoor workers and people with chronic medical conditions, said Caleb Smith, resiliency coordinator for the local advocacy group WE ACT for Environmental Justice. The start of the school year earlier this month was marked by uncomfortably hot indoor temperatures and broken air conditioners.

“Many schools in New York City are underserved by A/C,” Smith said. “There are already education barriers as it is. We want to make sure schools are a safe haven for these climate impacts.”

Smith and other advocates are urging city lawmakers to make the city more resilient against extreme heat. More parks and trees, plentiful cooling centers, and financial aid for A/C bills can all help protect New Yorkers from the worst effects of high temperatures.

Earlier this month, the New York City Council passed a Local Law that would require the city to include planting trees in its long-term sustainability planning. WE ACT has also called on the city to set a legal maximum indoor temperature during the summer months, putting the onus on landlords to ensure that their properties aren’t dangerously hot.

“Heat is the number one weather-related killer in the United States,” Smith said. “We have to keep ringing the bell to let our legislators know we can’t wait any longer.”

Pershing, meanwhile, says that we may need to rethink some of our seasonal rhythms, like starting school in early September.

“Schools have not had to deal with that amount of heat, and now they do,” he said. “Anytime you’ve built your life and society around a particular expectation of the climate, climate change has broken that.”