Philadelphia keeps breaking weather records: Biggest snowstorms. Most 90-degree days. Wettest months.
The extremes could be a sign of things to come.
Climate change is contributing to weather transformations in Philadelphia and other cities across the globe. A look at historical data shows how changes have accelerated locally.
Bigger snowstorms and hotter temperatures may seem contradictory, but they go hand-in-hand: The warmer the world gets, the warmer the oceans get — and the more moisture they pump into the atmosphere. That leads to heavier downpours and, when it's still cold enough in the winter, heavier snowfalls.
It's the perfect recipe for more record-breaking storms, meteorologists say.
"The past certainly is no longer a guide to the future," said Michael Mann, a climate scientist at Pennsylvania State University. "If we continue to pollute the atmosphere with carbon from the burning of fossil fuels, we will see ever-hotter temperatures, stronger storms, bigger flooding events."
Since 2000, Philadelphia has had 58 record highs — compared with five record lows.
But the biggest change is happening at nighttime, when temperatures are cooling off less. One big reason is the increased moisture in the atmosphere. The more humid the air, the less the temperature can fall.
Warmer nights pose health consequences, because they give bodies less time to recover from heat. That leaves already vulnerable populations — the elderly, people with breathing issues, those without air-conditioning — at higher risk of heat-related illnesses and death.
In Philadelphia, 104 people have died from heat-related causes in the last decade. The city said it does not break down the deaths by time of day.
Extreme weather strains municipal resources — and ultimately taxpayers. Philadelphia officials estimated in 2015 that climate change could cost an extra:
The cost of medical treatment and lost productivity associated with a surge in diseases such as asthma and COPD could also approach $20 million by 2050, the city estimated.
Earth is in its warmest period in the history of modern civilization, and it is "extremely likely" humans are causing the rise, scientists working for the U.S. government concluded last year. The globe posted its warmest years on record in 2014, 2015, and 2016. (2014 was later eclipsed by 2017, which now ranks as third-warmest.)