Ice cover on the upper Mississippi was fleeting this winter. Is this our future?

Anthony Larson describes himself as a hard-core ice fisher.

Living in La Crosse, Wisconsin, right next to the Mississippi River, he has the luxury of fulfilling that description. Once the river and its backwaters ice over each winter, he aims to fish every day, using his work commute to scope out particular spots he wants to hit. Even if all he can spare at the end of the day is 15 or 20 minutes, he goes for it.

This winter was different.

The above-average temperatures across the upper Midwest, driven in part by the El Niño climate pattern and in part by human-caused climate change, made for less than one month of safe ice on the river, scientists estimate. Though Larson was still able to get out on the ice, the conditions prevented him and his fellow anglers from getting to their favorite spots.

“We were all kind of trapped within a couple hundred yards of a shoreline,” he said, which affects the type of fish that can be caught and reduces the number.

The upper Mississippi River, as it snakes along Minnesota, Wisconsin, and Iowa, typically freezes during the coldest months of the year, particularly the more languid backwater channels. But even the river’s main channel — used by shipping traffic in warmer weather — freezes if it stays cold long enough. Things usually thaw out at the end of March.

This season, the last of that ice melted and was floating downstream at the end of February, said Kathi Jo Jankowski, a La Crosse-based research ecologist with the U.S. Geological Survey. Many described the winter conditions as something they’d never experienced before. But as climate change continues to progress, it could become familiar.

“We’re peering into the future of our ice conditions,” Jankowski said. “This year is going to give us a lot of interesting information about what iceless winters are going to look like.”

Warm, volatile winter caused unusual ice conditions

When snow fell across Wisconsin on Halloween, Jankowski said it made people hopeful that a great winter lay ahead. But the warm-up that occurred around Christmas Day thawed any ice that had accumulated. In early January, when U.S. Geological Survey staff monitored water quality on the river, they got into the water on regular boats instead of boats that can travel over ice, which they typically have to use at that time of year, Jankowski said.

Temperatures plunged in mid-January, causing the river to freeze up like normal. But it didn’t last long. The winter ended up being Wisconsin’s warmest on record.

The January deep freeze was followed by a quick warm-up that caused the ice to float downstream, Jankowski said. Conservation staff in Iowa, Illinois, and Missouri saw ice floes and “pancake ice” (round pieces of ice that form as a result of wave action), which are rare on that stretch of river.

Although the lack of snow put those unusual formations on display, that type of ice is weak, Jankowski said.

“It’s not the kind of ice that people are looking for if they’re going to try to walk out there or get out there fishing,” she said. “It’s beautiful, but a little more dangerous.”

It also made it hard for researchers in those states farther south, who don’t typically see much ice, to get out on the river. In Wisconsin, the opposite was true — Shawn Giblin, a Mississippi River water quality specialist for the Wisconsin Department of Natural Resources, said he was forced to cancel several sampling trips because the ice was unsafe or because there was no ice at all.

He described the season as “a bit of a bummer for a winter lover.”

Commercial shipping season started earlier than normal

Barge traffic on the river’s northern stretch halts each winter because of ice. Lake Pepin, a reservoir of the Mississippi River that stretches 21 miles between Reads Landing and Red Wing, Minnesota, is used as an indicator of when commercial shipping can start up again, because it’s typically the last place on the river to have ice cover.

The U.S. Army Corps of Engineers’ St. Paul District has conducted ice depth surveys on Lake Pepin for the last 30 years, the results of which they share with the shipping industry. Once ice on the lake is less than a foot thick, a towboat and barge can break through.

This year, for the first time, the surveys were canceled, because there wasn’t enough ice to measure. Patrick Moes, a spokesperson for the St. Paul District, said staff drove by the lake and saw it was mostly open.

On Saturday, shipping season officially began on the upper river, about a week earlier than average. If the Corps hadn’t been conducting maintenance on the river’s locks and dams over the winter, it could have begun even earlier, Moes said.

He said he was able to ice fish just once on Lake Pepin this year, during the bitter cold in January.

“My heart really goes out to all those outfitters and people that rely on winter recreation and activities to put food on the table,” he said, “because obviously, this winter has been unlike anything I’ve ever witnessed.”

This winter could give foresight on the future

It’s not yet clear what effect the lack of ice will have on the river ecosystem, Jankowski said. Without ice cover, sunlight can more easily penetrate the water column. That could bolster aquatic plant growth, but it could also spur earlier algae activity because the water is full of nutrients.

More open water also gives invasive carp better opportunities to move within the river, she said.

Ice cover on the upper Mississippi is already waning. Records from Lake Pepin dating back to 1843 show that the ice thaws about two weeks sooner today than it did then. And as the world warms, it’s a trend that’s expected to continue.

This winter, then, can be an opportunity to think about how to adapt to future ones with less ice, Jankowski said, including adjusting our lifestyles.

For Larson, that’s already in process. Though he wasn’t able to ice fish as much as he wanted, he used the time to pick up another hobby: falconry.

“This was a great year to hang the ice fishing stuff up, as much as it’s in my blood,” he said. “I was still able to find other adventures.”

Madeline Heim is a reporter at the Milwaukee Journal Sentinel. This story is a product of the Mississippi River Basin Ag & Water Desk, an independent reporting network based at the University of Missouri in partnership with Report for America, with major funding from the Walton Family Foundation.