Globally, last year was the second hottest on record, according to an analysis by NASA. The agency finds that 2017’s globally-averaged temperatures were second only to 2016. But Pittsburgh, Philadelphia, and other parts of the state didn’t see that kind of temperature rise. “Pennsylvania, it was actually the seventh warmest year on record,” says state climatologist Kyle Imhoff, based at Penn State University. “Not quite as warm as if you looked globally, but still a warm year any way you look at it.”

Imhoff says Pennsylvania has seen a 1-2 degree Fahrenheit rise in temperature in the last 100-150 years, but the warming isn’t happening during the day. “We’re getting warmer at night,” says Imhoff. “Night time temperatures are not as cold as they used to be.” 

Imhoff expects some benefits from this, like a longer growing season for crops.

LISTEN: “Pittsburgh’s Nights Getting Hotter. But Not in the Way You Think”

But in a region like Pittsburgh, air pollution is already a health issue. In Allegheny County there are about 250 deaths per year because of air pollution, almost all because of breathing fine particles. Carnegie Mellon University atmospheric chemist Neil Donahue says rising temperatures could worsen the problem. “The chemistry gets more aggressive,” he explains. “So levels of ozone go up, and levels of fine particles, especially organic fine particles go up as well.”

Donahue says those fine particles can trigger heart attacks, similar to smoking. Scientists aren’t seeing this increase yet, he says, because the temperature rise has been been relatively small in Pennsylvania so far.

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