On Wednesday morning, temperatures in Madison, Wisconsin, hovered in the negative 20s, the coldest the city has been in more than two decades. The University of Wisconsin canceled classes, the public library closed, and some bars even shut down. The city offered free bus rides and placed extra warming buses at transfer stations so that passengers wouldn’t have to wait outside. On Facebook, the Madison Police Department joked that it was canceling all criminal activities. (It advised would-be criminals to watch Netflix instead.)

But even as the city hunkered down for another frigid day, officials and experts were already thinking ahead, trying to anticipate what challenges the shifting environment would throw at them next. It’s not an easy task.

Climate change is happening, and we’re already feeling the effects. But exactly what the climate might look like 20 or 50 years from now in Madison, Wisconsin, or Chicago, Illinois, isn’t yet clear. Most climate scientists agree that the region will experience more extreme storms, but how much temperature variability there will be is less certain, Stephen Vavrus, a climate scientist at the University of Wisconsin in Madison, says. It’s not clear whether the changing climate will bring more moderation or more “weather whiplash,” he adds. This week’s frigid temperatures are even more surprising because this winter has been unusually mild.

It’s not clear whether the changing climate will bring more moderation or more “weather whiplash”

Extreme cold isn’t necessarily what comes to mind when people think about climate change, but some evidence suggests that these kinds of cold snaps could become more common as the climate warms. The current frigid temperatures in the Midwest are due to the Arctic polar vortex, the winds that normally swirl around the North Pole. Occasionally, the vortex will dip south or even fragment, sending frosty air into lower latitudes. This phenomenon is nothing new.

But climate change could increase the frequency of such dips. Winds in the vortex are driven by the temperature difference between the poles and the tropics. The larger the difference, the stronger the winds. As the climate warms, the poles are warming faster than middle latitudes. That could slow the winds and make the Arctic vortex weaker and wobblier. “When we have a weakened polar vortex, the winds tend to meander and then tend to dip southward,” says Vavrus.

At the same time, however, the Arctic is warming, so eventually, the wayward lobes of cold air might not be all that frigid. “The climate system is extremely complicated. So to simplify it this much — to say that a warming Arctic equals more cold air outbreaks — is pushing the limits of understanding the system,” Vavrus says. “There’s all these other factors going on.”

It’s this kind of complexity coupled with uncertainties about future greenhouse gas emissions that make long-term planning so difficult. Short-term planning is similarly challenging.

Robin Hutcheson, director of Minneapolis’ public works department, spent Wednesday morning preparing her crews for the dangerous cold and all the problems that might come with it. But by the weekend, meteorologists predict the city could be 40 degrees and rainy. So later this week, Hutcheson will send crews to clear off storm sewer grates so that melting snow doesn’t cause flooding. “It’s climate chaos. Our world and our work is getting less predictable,” she says. “We have to be really nimble.”

“It’s climate chaos. Our world and our work is getting less predictable.”

In Madison, the mayor’s office asked property owners to help city crews by “adopting” one of the city’s nearly 20,000 storm sewer inlets to make sure they are cleared of snow before a thaw sets in this weekend.

Jeanne Hoffman, facilities and sustainability manager for the City of Madison, points out that these kinds of infrastructure concerns are only part of the planning equation. Local governments also need to think about how to prepare vulnerable populations, such as the elderly and the homeless, for the effects of climate change. “We can come up with a list of places where we know vulnerable populations are,” she says, and find ways to educate and engage them. “It isn’t rocket science.”

On Wednesday, the Beacon, a daytime shelter for the homeless in Madison, opened early so that individuals could go directly from overnight shelters to the daytime facility without having to wait outside. The center also provided shuttles for those who wanted a ride. And two other organizations opened emergency shelters to handle overflow. But that hasn’t completely eliminated the impact of the cold. Michael Moody, guest services specialist at The Beacon, says several people were treated for frostbite or hypothermia on Wednesday.

As the globe warms, winters will become milder on average, and that could mean a whole new set of challenges for people living in these communities as the ecosystems around them shift. One impact that is already visible is the disappearance of ice on some of the lakes that dot the region. According to a new study published in Nature Climate Change, an estimated 15,000 lakes freeze only intermittently, and that number is expected to rise in the coming decades. Even if the world can limit the warming to 2 degrees Celsius, the researchers predict that the number of lakes with intermittent ice will more than double to 35,300. “Eventually, some of these lakes will have very few or no years when there’s sufficient ice to re-create on them,” says John Magnuson, an ecologist at the University of Wisconsin and one of the authors of the study.

“I think of what we’re in the process of losing.”

That’s not just a problem for those who want to ice fish or skate; it’s a problem for entire communities. Winter festivals and tournaments in the Midwest attract tourists. “There are dollar values associated with recreational use,” Magnuson says. What’s more, lake ice in the north is “part of a sense of place.”

This winter, Madison’s Lake Mendota froze in mid-December, thawed less than a week later, and then didn’t freeze over again until mid-January. That’s the third latest ice ever recorded, Magnuson says. And even when the lake had ice, much of it was so thin that people couldn’t walk on it. The period of time between when the lake freezes and when the ice becomes thick enough to support winter activities “is actually a sad period of time,” he says. “I think of what we’re in the process of losing.”