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Film captures record-setting swim in warming Lake Superior

Marathon swimmers set a new distance relay record in a film that highlights the impact of warming waters in Lake Superior. One of five Great Lakes, it is the largest freshwater lake in the world by surface area. Over 24 hours, the athletes swam 46 miles without wetsuits to set the new record. The film, A Sea Change for Superior: The Warming of the World’s Largest Lake, captures what the effects of climate change mean for the ecosystems and communities that depend on it.

Warming waters

The Great Lakes Commission reports that Lake Superior is one of the fastest-warming lakes. Part of the interconnected chain of freshwater lakes along the Canadian-US border, it holds 10% of the world’s surface freshwater.

In August, University of Minnesota Duluth scientists deployed additional buoys in the lake’s western waters to collect data. Over the decades, the data has provided information for research, weather forecasting, marine safety, commercial fishing, and recreational use. As a result, scientists have also noted warming lake temperatures.

Jay Austin, professor and physical limnologist at the Large Lakes Observatory in Duluth, said, “The most unusual data has been Lake Superior’s surface temperatures reaching 70ºF.” He went on to add, “The lake has warmed one degree per decade since the 1980s, making it one of the fastest-warming lakes in the world. We specifically want to understand how that interaction impacts the lake and how it is changing over time.” Historically, Lake Superior’s year-round temperatures have hovered around 40ºF.

Warming temperatures aren’t the only issue. PFAS, or Perfluoroalkyl and Polyfluoroalkyl Substances, are now impacting the region. A recent study reveals that rain has spread PFAS into all five Great Lakes.

Swim challenge

In August 2023, world-class distance swimmers lined up along Superior’s shore. Working in relays, they swam from Split Rock Lighthouse State Park south to the city of Duluth. According to MPR News, six swimmers alternated every hour in water temperatures that hovered in the mid-60s. Supported by a film crew, they completed the longest documented swim in the lake without wetsuits or artificial aids.

Team captain Karen Zemlin, who has been swimming in Lake Superior for two decades expressed her concern. “I feel like I’m noticing more 70-degree water than I would have,” she told the news. “I feel like I have to go farther sometimes to get away from the 70-degree water because that’s too warm for my purposes.”

The film explores how climate change is transforming Lake Superior’s waters and examines its impact on local ecosystems and wildlife. Scientists in the documentary describe how warming trends could affect Tribal and other communities living and working along the North Shore as well.

Hamline’s Center for Global Environmental Education produced the one-hour documentary. Funding was provided through NOAA’s Office for Coastal Management, the MN Department of Natural Resources, The Manitou Fund, and Odyssey Resorts. The film aired on Sunday, 10/20.

The swim challenge route covered 46 miles along Minnesota’s North Shore. (Map Quetico Superior Wilderness News/@Caltopo)

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Pam Wright, Contributor Quetico Superior Wilderness News

Wilderness guide and outdoorswoman Pam Wright has been exploring wild places since her youth. Remaining curious, she has navigated remote lakes in Canada by canoe, backpacked some of the highest mountains in the Sierra Nevada, and completed a thru-hike of the Superior Hiking Trail. Her professional roles include working as a wilderness guide in northern Minnesota and providing online education for outdoor enthusiasts.






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