Climate-saving transit trips are dropping even as climate change makes weather worse, a new study finds — and to stop the vicious cycle, America needs to better climate-proof its transit networks and encourage more people to choose shared modes now.

A recent study of 43 major U.S. transit networks revealed that ridership dropped during long stretches of rain, heat, or other prolonged extreme weather events that scientists link to climate change, at least in the 17 years between when the National Transit Database began collecting stats and 2019, the last year before the pandemic decimated ridership. That held true even when researchers controlled for what constitutes “extreme” weather in climates as diverse as Philadelphia and Phoenix, as well as how baseline transit ridership tends to differ depending on the race, education, and income mix of each community.

Of course, it’s not exactly news that no one likes to wait for the bus in a bad storm — and since people with no other options will ride regardless, the decline wasn’t very large. Still, the University of Oregon team behind the analysis warn that climate change-related ridership losses could get far worse, and that passengers are suffering and even dying at stops right now.

“Even now, you can end up waiting outside for the bus for quite a while, and that’s very uncomfortable in 90-degree heat,” said Nicole Ngo, the leader author on the paper. “And for certain populations — especially older adults — that can be dangerous, [even as] a lot of older adults use public transit as their primary mode of transportation, either due to mobility issues or due to income.”

Ngo explains that climate change doesn’t only tempt riders to skip transit trips on intemperate days – or even to take private vehicles instead. During bad snow and rain storms, buses can get snarled in the same traffic as cars, and rail tracks can warp in intense heat, forcing agencies to run trains more slowly or cancel trips outright, leaving even those who would pay the fare with no ride to take.

Worse, as extreme weather events drag on, ridership losses compound—  especially during the harshest heat waves, which had a particularly marked effect in the latter half of the study period. And considering that transit is often low income residents’ only route to neighborhood cooling centers – and they can’t always afford to install or run air conditioning at home — that means the health impacts of heat are being compounded, too.

“It’s not just a matter of very hot days affecting travel behavior,” she added. “It’s much more pronounced when you have these consecutive days of heat or extreme weather.”

Ngo says apart from recognizing transit’s integral role in cutting emissions, transportation leaders need to confront the role of climate change itself in eroding ridership. That means not just improving and expanding service to make buses and trains a reasonable alternative to driving, but putting climate-controlling measures at stops, like shade, heat, A/C, cooling greenery, or anything else the climate requires — and doing so at a vast scale, considering that only about one-fifth of U.S. bus stops even have basic shelters now.

Ngo acknowledged that neither action will be easy, especially in a political climate where federal leaders are denying even the existence climate change. But she says it’s critical for them to accept the reality of extreme weather’s impact on transit, no matter what they believe is causing it.

“We need to realize that extreme weather is becoming much more common, and it’s not going away,” Ngo added. “We need to ensure that cities and transit agencies are aware that this is also hurting their bottom line. The effect is small now, but with heat waves and days with heavy precipitation increasing, the effects could grow over time.”