At about 7:30 a.m. Wednesday morning, Craig Collins emerged dripping from Lake Superior, wearing just a small swimsuit and a yellow swim cap, and jogged on to the beach in Canal Park in Duluth. A couple dozen onlookers greeted him, clapping and cheering.
“I love this so much,” the 64-year old from Minneapolis said, grinning. And why not? He had just completed the final leg of a non-stop, 48-mile relay swim that began at Split Rock Lighthouse State Park on Tuesday morning, and ended in Duluth 23 1/2 hours after the first team member entered the water.
The six swimmers alternated every hour, and swam through the night, accompanied by two support boats and a documentary film crew. They completed the longest observed, documented swim in Lake Superior without wetsuits or artificial aids.
“We got a little bit of a lot of things, but Superior didn’t beat us this day,” said team captain Karen Zemlin, 55, of Plymouth, Minn.
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Swimmers had to contend with 3 to 5 foot swells, with whitecaps later in the afternoon. Sometimes waves would wash over them. “Which was super, super challenging,” Zemlin said. “You just have to have enough experience not to panic.”
Fortunately, they weren’t swimming against the waves — otherwise Zemlin said they may not have been able to finish. Several swimmers also coped with mild seasickness. Zemlin said her stomach was growling after each of her swims, but she felt too sick to eat.
One challenge Lake Superior did not throw at the swimmers was super-frigid water. The water temperature held steady in the lows sixties, even hitting 66 degrees Fahrenheit when they neared Duluth.
That’s still chilly by most swimmers’ standards. A typical swimming pool is heated to around 80 degrees. But it’s relatively balmy for Lake Superior, one of the largest and coldest lakes in the world.
And that was one of the motivating forces for the swim — not only to set a record, but also to raise awareness of the impact of climate change on Lake Superior —one of the fastest warming lakes in the world.
“It’s kind of bittersweet,” said Casey McGrath, 51, of Minneapolis. “It’s a cool experience that we were able to have, but really in some ways we shouldn’t have been able to do it, not without wetsuits anyway.”
Swimming the channel
For Karen Zemlin, who began the relay at 8 a.m. Tuesday, swimming in Lake Superior was like slipping into an old friend’s cool embrace.
She’s been swimming in Lake Superior for nearly two decades. It’s where she came to train after she first attempted to swim across the English Channel in 2015.
For that famed swim, she battled the water for 11 hours, and made it almost all the way across. But with less than an hour to go, her support team pulled her out. She was suffering from hypothermia.
“I couldn’t remember it was France anymore. I knew I wanted to get over there. But I couldn’t have told you it was France,” she recalled.
Her hands were like claws — she couldn’t open her water bottle.
“When we processed it later, I realized that I remembered the first six hours of the swim. But the next six hours of the swim to me in my mind was like an hour and a half. So I lost hours of what was going on there.”
Zemlin knew she needed to spend more time training in cold water. The lakes she swam in the Twin Cities were often 70 degrees or warmer. So she came to Lake Superior, in search of 60 degree water, or even colder.
“I tell people if I’m swimming in water 55 degrees or below, it’s like having an ice cream headache in my arms and my legs. So it’s like that tingly, really sore feeling that you get in your forehead when you eat ice cream too fast.”
When she returned to swim the English Channel again in 2019, she not only made it across, she set a record for women over 50. “I just had a great swim,” Zemlin said. “I just felt like in control and ready to go.”
A warming Superior
But the water in Lake Superior, while still often extremely cold, is often not as icy as in the past.
“I feel like I’m noticing more 70 degree water than I would have,” Zemlin said. “And 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."
What Zemlin is feeling first-hand, submerged in the water, is reflected in the data.
“Recent years since 1998 tend to be on the order of four to five degrees Fahrenheit warmer than pre-1998,” said Jay Austin, a professor at the Large Lakes Observatory at the University of Minnesota Duluth.
That rapid warming is largely due to warmer winters. The average winter night in Minnesota is about six degrees warmer than the early 1900s. That’s led to a sharp reduction in ice cover on Lake Superior — about 80 percent between 1973 and 2010.
Winters with low ice cover tend to be followed by summers with warm water. And just a few degrees warming can have a huge impact on ice cover.
“The difference between a heavy ice year where people are out recreating on the ice and going visiting the ice caves, and a year with basically no open lake ice, can be due to differences in average winter air temperatures on the order of 4 to 5 degrees Fahrenheit,” Austin said.
Austin stresses that Lake Superior’s famously frigid water is not going away. For example, just a couple weeks ago, water temperature along the North Shore shifted suddenly from in the low 60s to the upper 30s, due to a process known as upwelling. That’s when winds push warm surface water away from shore, allowing the cold water deep in the lake to rise to the surface.
And there will still be cold winters during which the lake is coated in ice, followed by cold water in the summer. But those years are becoming more and more rare.
“There are going to be more and more warm years, where it’s reasonably comfortable to swim, and fewer and fewer of the cold years,” said Austin. “But it doesn’t mean the cold years are going away.”
A warming Lake Superior may mean more comfortable swimming much of the time. But it also has more detrimental impacts, Austin says.
Warmer water, combined with increased runoff from huge rainstorms associated with climate change, have led to the formation of toxic algae blooms in Lake Superior. And fish species native to Lake Superior, including herring, that need cold water to thrive, have shown signs of decline.
The swimmers hope to draw attention to those changes through a partnership with Hamline University’s Center for Global Environmental Education, which is filming the swim, along with PBS North in Duluth, to include in a documentary about climate change and Lake Superior that’s due out later this year.
“What we’re doing is really celebrating what’s extraordinary about the lake, and its cold water is obviously at the heart of that,” said John Shepard, associate director of the center.
“We’re hoping it will just help people think about the fact that the lake is warming, and that what they accomplished is more feasible now than it would have been before.”
Katya Gordon of Two Harbors, Minn., stood on the Duluth beach to welcome the swimmers Wednesday morning. She has a personal stake in their mission: She and her husband Mark take young adults and teenagers sailing around Lake Superior to teach them firsthand about the impacts of climate change on Lake Superior.
In 2010, while sailing across the lake from the South Shore of Wisconsin to Minnesota’s North Shore, they encountered 70 degree water.
“And Mark stopped the boat, and he told everyone to get out and swim,” Katya Gordon recalled. “This is never gonna happen again!” he said. It was like bath water.
But what the Gordons thought was a one-off has become the norm. Almost every year since then, they have encountered 70 degree water temperatures. And at least one year, it reached 80 degrees.
“In our minds, that’s sort of what we hear about climate change,” Gordon said. “What was once unthinkable becomes commonplace.”