As winters warm, Minnesota lakes lose ice | State

As Minnesota’s lakes warm due to climate change, they lose their ice cover that turns them into playgrounds for state residents who can withstand winter.

Data shows that ice cover on Minnesota’s lakes has declined an average of 10 to 14 days over the past 50 years, state environmental officials said at a press conference on Friday. the shores of Medicine Lake in Plymouth.

“In our own backyards, climate change is eroding the ice season on the lakes,” said Katrina Kessler, commissioner of the Minnesota Pollution Control Agency.

Ice conditions vary considerably from year to year and from lake to lake. But based on data collected by state agencies and volunteers, since 1967, ice-in dates have shifted about nine days later on average, while ice-out dates have been shifted d. ‘about four to five days earlier.

A two-week shortened ice season could have a dramatic impact on beloved Minnesota traditions such as ice fishing, snowshoeing, snowmobiling, and cross-country skiing, and hurt local businesses that depend on tourism and tourism. winter recreation, officials said.

“We are already seeing the impact of climate on our way of life in Minnesota, which includes our natural resources, our outdoors and our economy,” said Sarah Strommen, commissioner of the state’s Department of Natural Resources.

“We all know Minnesota as the Land of 10,000 Lakes. It’s the state of hockey or the state of the fishery, ”Strommen said. “These unique qualities of our state’s identity face an uncertain future due to warming temperatures and shorter ice seasons. “

State climatologist Pete Boulay is one of the custodians of the numerous ice entry and exit data records for Minnesota lakes. Most of the data was collected by volunteers who lived on the lakes.

“We went to people where they had dates written on cupboards to get the ice cream in and out dates,” he said. “So we’re still building the database. “

This year, ice formed on Medicine Lake on Dec. 7, a week later than the median freeze-up date of Nov. 30, Boulay said. The lake has lost nearly 12 days of ice cover since 1967.

“So here we have a real-time witness of what’s going on with the lakes,” he said.

Some lakes in northern Minnesota have experienced even greater declines in ice cover. Lake Bemidji has lost nearly 19 days over the past half century.

Winter recreation advocates fear that a shorter season with strong, stable ice could negatively impact their favorite activities.

Michelle Morey is president of Women Anglers of Minnesota, a 1,000-member nonprofit that helps women and children connect with the sport of fishing. It also sponsors workshops and fishing tournaments.

Morey said interest in ice fishing has increased, in part because ice fishermen don’t need a boat. But she said recent seasons of warm, melting ice on lakes in southern Minnesota pose a safety risk.

“Ice fishermen need to be even more aware of changing conditions, especially fishermen with wheelhouses or ATVs who are at greater risk of crossing ice or getting stuck on muddy lakes,” Morey said.

Besides recreation, warmer water and a shortened ice season can also impact a lake’s ecosystem, leading to more toxic algal blooms and invasive species, as well as shifting fish populations. . Walleye, for example, prefer cooler waters and no longer thrive in warmer lakes, Strommen said.

The effects on lake ice are an indicator of changes occurring with the state’s climate, Kessler said. Minnesota’s winters, in particular, heat up faster than its summers, she said.

“What we put in the air affects our waters,” Kessler said. “The release of greenhouse gases from burning fossil fuels for transportation and power generation, for example, is changing our climate. “

Kessler said the state needs to take bold action on climate change, including investing in cleaner energy, building more energy-efficient homes and businesses, and promoting cleaner transportation options, such as electric vehicles.

Ann Mulholland, director of the state chapter of the nonprofit Nature Conservancy, said Minnesota should also seek nature-based solutions, including planting trees and cover crops and restoring them. forests and peatlands that help absorb carbon.

Changes in lake ice are also a good way to measure the impacts of climate change because they are not as variable as weather conditions, which can be influenced by El Niño or other patterns, said John Magnuson, professor. emeritus at the University of Wisconsin-Madison. Limnology Center. Magnuson did not participate in Friday’s event, but studied the lake ice changes in depth.

“It takes a lot of heat to melt the ice, and it takes a lot of cooling to freeze the ice,” he said. “So it’s not like the day-to-day weather. “

Additionally, the lakes are scattered not only in wilderness areas, but also in towns where people have lived and interacted with them for years, Magnuson said.

There have been detailed records of ice entry and exit dates for northern hemisphere lakes for centuries. This is because in Minnesota and elsewhere in the world, lake ice has played an important role. People harvested it for food preservation or used it as a means of transportation, Magnuson said.

“When the lake freezes, all of a sudden you had a transportation lane available to get you to the other side of the lake, or to get to a town you hadn’t been to in some time. , or a neighbor or relative, ”he said.

On lakes in the northern hemisphere, Magnuson’s research revealed a similar pattern of ice loss.

“It’s global,” he said. “It is not a unique characteristic of any particular lake or state.”

Less ice cover could cause physical and ecological changes in a lake, Magnuson said. Ice and snow reduce the amount of light that can enter the water below, which affects the productivity of plants and algae.

It could also alter thermal stratification patterns – when lakes separate into different layers of density after the sun has warmed the surface – and the natural mixing or renewal that occurs in spring and fall. This process is important for the distribution of oxygen that living organisms need to survive.

The trend for shorter ice seasons is also having a human impact, said Lesley Knoll, associate director at the University of Minnesota’s Itasca Biological Station.

In Minnesota, where winters are long, the use of lake ice plays an important cultural role and is linked to people’s sense of belonging, Knoll said.

“As we have less reliable lake ice, there will be a loss in how we use it – for the cultural or social or even economic benefits we derive from it,” she said.

In 2019, Knoll wrote a study examining the impact of shorter ice seasons on cultural traditions and recreation. These included ice fishing in Minnesota, ice skating races in Sweden, and Shinto religious ceremonies on frozen lakes in Japan.

Minnesota hosts nearly 100 ice fishing tournaments across the state each year, Knoll said. These events draw a lot of people to local communities during the winter season, when tourism otherwise tends to be slow, she said.

But during warmer winters, ice fishing tournaments were canceled more frequently, especially in central Minnesota, according to the study.

For the many businesses that rely on frozen lakes, including resorts, ice fishing outfitters, and snowmobile rental companies, a predictable lack of ice can be problematic.

At Trapper’s Landing Lodge on Leech Lake in Walker, the winter season is getting busier with the growing popularity of ice fishing, said manager Josh Bullivant.

“Even though people say the ice season is shorter, the industry as a whole is the fastest growing outdoor sport,” Bullivant said.

Trapper’s Lodge has cabins on shore and a restaurant, and also rents fishing gear and luxurious coolers with leather sofas and TVs. While most visitors come for the weekend, some stay a full week to fish for walleye, pike and perch.

Bullivant said the ice conditions on Leech Lake vary from year to year. Last year ice covered the lake for seven months, he said, but this year it formed a little later than usual.

While Bullivant said he does not have enough data to know whether temperature changes are caused by climate change, he believes it is a factor.

“There is definitely something in the extremes,” he said. “Now all of a sudden it’s going to be cold and we’ll have a great amount of ice. And then all of a sudden it’s 80 degrees, and it’s all gone in one day in March.

© 2020 Minnesota Public Radio. All rights reserved.

Comments are closed.