The dangers of warming winter lakes

Summary

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Short Wave – "The dangers of warming winter lakes"

Host: Emily Kwong
Date: February 27, 2026
Guest Contributors: Burley McCoy (Short Wave producer/reporter), Hilary Dugan (lake scientist), Justin Tooze (firefighter/lake rescue team), Sapna Sharma (global change biologist), James Tighe (Clean Lakes Alliance founder)

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Episode Overview

This episode explores how shorter, warmer winters are making ice cover on lakes less reliable—changing not only northern cultural traditions, but also community safety. Reporter Burley McCoy dives into the science behind ice formation and weakening, attends a major winter festival in Madison, Wisconsin, and tags along with a lake rescue team to understand how climate change is already putting people at greater risk on the ice.

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Key Discussion Points & Insights

1. Winter Traditions and the Changing Landscape

• Festival Spotlight: “Frozen Assets” (01:16 – 02:14)

  • Burley describes her trip to Lake Mendota in Madison, WI for the annual Frozen Assets festival: "There is ice hockey, curling, ice skating. People are flying these giant, colorful kites on the ice. A skydiver is landing on the ice right now” (01:20 – Burley McCoy).
  • A unique tradition: a thousand people warming up for a 5k race by jumping together to shake the ice.

• Cultural Significance and Vulnerability (04:39 – 05:36)

  • Emily reflects on the importance of winter lake activities in northern communities: “It reminds me of lacing up my skates on the weekend just to go out on the lake and have fun, though... nervous every time to step on it" (05:19 – Emily Kwong).

2. Ice Science and Safety

• Types of Ice and Safe Thickness (03:41 – 04:39)
  • Black Ice: “Black ice is really strong and it's what freezes in the lake water itself... it's strongest” (03:58 – Hilary Dugan).
  • White Ice: “White ice is what's forming when you freeze snow or slush. And that white ice has a lot more air in it, just weaker in general" (04:14 – Hilary Dugan).
  • For safe walking: a person needs at least 4 inches of black ice.

3. Unpredictable Ice Cover — Festival Disruption

• Ice Not Forming Reliably (05:36 – 06:04)
  • Hilary Dugan: “Two years ago, the ice didn't form thick enough in time for the festival, so the festival on the ice was canceled, and it was sort of moved to the shore... takes away the spirit of what this festival's about” (05:52).

4. Lake Rescue and Increasing Dangers

• Fire Department Lake Rescue Training (06:07 – 08:49)

  • Burley joins Madison’s lake rescue team for a simulation: “I put on this giant yellow immersion suit. They call it a Gumby suit because you basically walk like the green claymation character Gumby" (06:46 – Burley McCoy).
  • Practice includes jumping into open water near unstable ice and using a rescue sled.

• Real-Life Rescue Scenarios and Hazards (09:00 – 10:05)

  • Justin Tooze explains: “Last year was definitely our busiest year just because of the mild winter... it looks like solid ice, but it’s not solid ice at all” (09:05).
  • False ice shelves due to multiple freeze-thaw cycles increase risk: “A person... fell through... It wasn't deep water, but the ice shelf made it so he couldn't get out” (09:25).
  • The rescued person was in frigid water for about 25 minutes (09:42), and survived—a rare good outcome.

5. The Rising Toll of Climate Change on Ice and Drownings

• Increasing Global Incidents (10:18 – 10:50)

  • Sapna Sharma shares research: “We've documented over 4,000 fatal drownings through ice... across 10 countries” (10:29).
  • “50% of those drownings can be explained by winter air temperatures, such that in warmer winters, more people drown” (10:50).

• The Role of ‘Winter Weirding’ (11:16 – 11:44)

  • Hilary Dugan: “We'll just have these really cold polar vortex events followed by heat waves... winter is no longer this duration of cold weather. It kind of bounces around all over the place” (11:23).

• The Future of Lake Ice (11:44 – 12:00)

  • Sapna Sharma: “You might expect 10 to 28 days less ice cover by the end of the century. And at current greenhouse gas emission scenarios, we forecast about 5,700 lakes may permanently become ice free within this century” (11:44).

6. Broader Impacts of Vanishing Ice

• Cultural & Infrastructural Losses (12:22 – 12:53)
  • Loss of ice affects not just recreation, but practical needs:
    • “It matters for winter ice roads... so many northern communities, especially remote communities, and many indigenous communities actually require the use of winter ice roads to access food, fuel, medical supplies and even social connections in the winter” (12:24 – Sapna Sharma).
  • Emily: “Yeah, ice is an invaluable resource, actually in a lot of places. And it is being threatened by climate change” (12:48).

7. Call to Action & Hope for Change

• Sorrow and Activism (12:53 – 13:23)
  • James Tighe: “Once people care about something, then they're gonna wanna protect it. You know, things are changing and if there's a year that you can't be on the ice, then people are gonna start to wonder why, and maybe they'll ask for a change” (13:09).

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Notable Quotes

• Burley McCoy, on the culture of lake life:
  “In Madison, in many places downtown, people can always see one of the two lakes surrounding the city. It's just part of everyday life there, and a lot of people take advantage of that.” (04:53)

• Hilary Dugan, on changing winters:
  “Winter is no longer this duration of cold weather. It kind of bounces around all over the place.” (11:23)

• Sapna Sharma, on the staggering loss:
  “At current greenhouse gas emission scenarios, we forecast about 5,700 lakes may permanently become ice free within this century.” (11:44)

• James Tighe, on the ripple effect of change:
  “Once people care about something, then they're gonna wanna protect it... if there's a year that you can't be on the ice, then people are gonna start to wonder why, and maybe they'll ask for a change.” (13:09)

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Key Timestamps

• 01:16 – Burley describes the Frozen Assets festival.
• 03:41 – Science of ice thickness and types (black ice vs. white ice).
• 05:36 – Reliability of ice; festival forced off ice due to poor conditions.
• 06:15 – Introduction to lake rescue training (Justin Tooze).
• 09:00 – Mild winters and changing rescue needs.
• 10:29 – Global data on fatal drownings and warming winters.
• 11:23 – "Winter weirding" and erratic freeze-thaw cycles.
• 11:44 – Future projections: thousands of lakes losing winter ice.
• 12:24 – Social and infrastructure impacts for communities.
• 13:09 – Cultural loss as a catalyst for climate action.

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Conclusion

This episode blends personal reporting, practical rescue exercises, and science interviews to reveal the profound effects of climate change on a beloved aspect of northern life: winter lake ice. Warming trends jeopardize safety, traditions, and even essential infrastructure, raising urgent questions for communities who depend on frozen lakes. The story closes with a note of hope: as ice becomes less reliable, perhaps public concern will grow into action and protection for future winters.

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Transcript

[NPR Announcer]

How could your favorite NPR podcast get any better? Well, what if it had bonus features such as extended interviews and zero sponsor breaks? There is a remarkably easy way to turn that fantasy into reality. It's called NPR. You get perks across more than 25 NPR podcasts while supporting the teams that make them. Make great podcasts even Greater by visiting

[Emily Kwong]

plus.NPR.org you're listening to Short Wave from NPR. Hey, shortwavers. Emily Kwong here. Quick reminder. Short Wave comes out four days a week, Monday through Wednesday and Friday. So to make sure you never miss an episode, look for the follow button on your podcast app and give it a little boop. Thank you kindly. All right, now it's my great pleasure to welcome Short wave producer Burley McCoy. Hey, Burley.

[Burley McCoy]

Hey, Emily. So, as you know, winter is my dam. I ice fish all winter on a frozen lake in Northwest Montana, where I live.

[Emily Kwong]

Yes, you are our resident shortwave ice queen.

[Burley McCoy]

Thank you. And I'm not the only one who takes ice seriously. Almost every year since 2011, a huge lake in Madison, Wisconsin, has frozen over enough to support an entire festival. It's called Frozen Assets. And that's where I headed to report this story.

[Emily Kwong]

Ooh, this sounds fun. What happens at Frozen Assets?

[Burley McCoy]

So on and near the ice of Lake Mendota, there is ice hockey, curling, ice skating. People are flying these giants giant, colorful kites on the ice. A skydiver is landing on the ice right now.

[Emily Kwong]

That's incredible.

[Burley McCoy]

And they did this warm up for a 5k where more than a thousand people jump up and down on the ice to make it shake.

[Emily Kwong]

What? Why would you do that?

[Burley McCoy]

I don't know. I did not like it.

[NPR Announcer]

This lake is over 14 inches, so it's safe. But can it shake?

[Burley McCoy]

So this is James Tai, the executive director and founder of Clean Lakes alliance, which puts on the festival. But, Emily, this lake, which freezes every year, this year, with ice thick enough that it could have held an entire fleet of trucks, might one day not freeze at all. And thousands of others may stop, too, like, soon.

[Hilary Dugan]

I could foresee in my lifetime, certainly in winter, when Mendota doesn't freeze.

[Emily Kwong]

Today on the show, how changing lake ice is altering culture, community, and safety on the ice.

[Burley McCoy]

Plus, I go out with Madison's lake rescue team to see how they train for emergencies when someone falls through.

[Emily Kwong]

You're listening to Short Wave, the science podcast from npr.

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[Emily Kwong]

Burley, so we are talking about lake ice, which remind me, when is it safe to walk on lake ice?

[Burley McCoy]

Yeah. So I double checked this with Hilary Dugan at the festival. She's a scientist who studies inland lakes and she says it's safe for a person to walk on ice when there is 4 inches of black ice.

[Hilary Dugan]

Black ice is really strong and it's what freezes in the lake water itself. So it's what's freezing downward.

[Burley McCoy]

So black ice, which is called that because it's clear and appears black, is strongest. But it's not the only type of ice.

[Hilary Dugan]

White ice is what's forming when you freeze snow or slush. And that white ice has a lot more air in it, just weaker in

[Burley McCoy]

general because of all the air. White ice scatters more light, isn't clear, and it looks white. It's less strong, and so it's less safe. And unlike black ice, it's tricky to say how much white ice is safe to walk on because the amount of air in it can be variable and it's often mixed with black ice.

[Emily Kwong]

Okay, so you went to this festival on a frozen lake with clearly enough black ice for you to stand on. And it sounds true to the spirit of northern communities. I mean, celebrating winter and making it a part of the culture there.

[Burley McCoy]

Absolutely. That's very true. In Madison, in many places downtown, people can always see one of the two lakes surrounding the city. It's just part of everyday life there, and a lot of people take advantage of that. In one of the lakes, there's this bay where in the winter, dozens, if not hundreds of people are ice fishing every day. I mean, this is a place that embraces winter. When I was at the frozen assets Festival, we walked by people eating snow cones. It was 10 degrees outside.

[Emily Kwong]

I spent some years in Maine and in Alaska, and it reminds me of lacing up my skates on the weekend just to go out on the lake and have fun, though it also reminds me of how nervous I was every time to step on it. I could not imagine going out to a whole festival on a lake. That's a lot of weight on that body of water.

[Burley McCoy]

Though at Lake Mendota, it's not every year anymore. Oh, Hillary told me that Lake Mendota does freeze over every year. There's even a contest where people guess what day that'll happen. But two years ago, the ice didn't form thick enough in time for the

[Hilary Dugan]

festival, so the festival on the ice was canceled, and it was sort of moved to the shore, which is really unfortunate. It was still fun. You know, we still had a lot of the same things, but, you know, takes away the spirit of what this festival's about.

[Emily Kwong]

At the same time, better. Better for people to be on solid ground, you know?

[Burley McCoy]

Yeah. And that made me wonder about safety on lake ice and how it might be changing. So I went to another expert. I'll let him introduce himself.

[Justin Tooze]

Justin Tooze. I'm a firefighter down at Station 1, Madison, Wisconsin, fire Department.

[Burley McCoy]

Justin is part of the lake Rescue Team, a group of firefighters who, among other things, are professionally trained to dive and rescue people who have fallen through the ice. I join them on one of their training exercises.

[Emily Kwong]

Nice.

[Burley McCoy]

So we went to Lake Monona, which is also right in town, to a spot where a river flows into the lake, which basically means there's always open water in that area. Ooh.

[Emily Kwong]

Sounds like the perfect place for practicing rescues. If you're the Madison, Wisconsin, Fire Department.

[Burley McCoy]

I think that's exactly the thought. So I put on this giant yellow immersion suit. On it goes. They call it a Gumby suit because you basically walk like the green claymation character Gumby. If you try to move kind of

[Justin Tooze]

one size fits all. So they might be.

[Burley McCoy]

One size fits all usually means men's size. So I followed a couple of firefighters also wearing these suits onto the ice, including Justin. We walked parallel to the river at first, then started moving toward it. We stepped over this huge ice crack where you could see the water, and they told me it's features like these, they can form from warmer water flowing into a lake or from, like, natural ice expansions and contractions. These are the places weaker ice can exist and are often where people will fall in. So we Cleared the crack, walked right to the edge of where the ice stops and the lake water starts. Justin got in first.

[Justin Tooze]

Yeah. Whenever you're ready to try it, we can throw you in.

[Burley McCoy]

I'm ready.

[Justin Tooze]

All right.

[Burley McCoy]

Hey, Lou.

[Justin Tooze]

Burleigh's gonna go in.

[Burley McCoy]

They didn't throw me in. I kind of got down on the ice, then went in backwards off the edge.

[Justin Tooze]

All right. So it's actually only like 4ft here, so you can't touch. You'll feel a little pressure on your legs.

[Burley McCoy]

All right. Oh, this is nice.

[Justin Tooze]

Yeah. If you want to lean back, I can hold on to you. You can kind of feel how it. How it is. So it's super buoyant.

[Burley McCoy]

Yeah.

[Justin Tooze]

Yeah. Keep you warm, actually. Like, the longer you're in it, the warmer you get.

[Burley McCoy]

And I just floated there while holding onto the ice for a few minutes.

[Emily Kwong]

Was it cold?

[Hilary Dugan]

No.

[Burley McCoy]

I was in this suit that made it kind of comfortable. And I had the lake rescue team around, so it wasn't scary or anything. It was pretty much the safest situation I could ever be in, going into a frozen lake.

[Justin Tooze]

Ready to get rescued?

[Burley McCoy]

I'm ready to get rescued. So another team member brought over this bright yellow rescue sled and attached my arms into a thicker out. Then he flagged the shore team to start pulling on this ice anchored rope that was attached to the sled.

[Emily Kwong]

Get her out, gentlemen.

[Burley McCoy]

It was all pretty quick.

[Emily Kwong]

Cool to hear how they practice. How often are they doing it in reality? Like, how often are they rescuing people?

[Burley McCoy]

Yeah, this year, not a lot, because the ice has been super thick. But that's not always the case.

[Justin Tooze]

Last year was definitely our busiest year just because of the mild winter.

[Burley McCoy]

Justin said that's because there were multiple freezes and thaws, which led to a particular kind of ice shelf that still

[Justin Tooze]

super dangerous when there's solid ice and then there's water on top of it, and then another ice formation forms on top of that water. So it looks like solid ice, but

[Burley McCoy]

it's not solid ice at all. And a person who was walking on the ice at night fell through. Oh, gosh.

[Justin Tooze]

It wasn't deep water, but the ice shelf made it so he couldn't get out of the water. So he would. He would have been gone if we wouldn't have been able to find him.

[Emily Kwong]

Was he okay? So they got him out.

[Burley McCoy]

They got him out. And in drone footage from the rescue, you can see that the ice just keeps breaking up when the rescuers are trying to get to them. And when they all get pulled off the Ice like it just keeps breaking up because of this false ice shelf that Justin was talking about. And Justin said the person was probably in the water for around 25 minutes trying to get out of the water before they called for help. But they were okay.

[Emily Kwong]

I'm so glad to hear they were okay because it is incredibly dangerous. I mean, falling into cold water can kill you in less than a minute. Many people die within just minutes from cold shock. So not every rescue has a good outcome.

[Burley McCoy]

Yeah, unfortunately, they don't. And the frequency of both people going through the ice and people drowning from ice breakthroughs are increasing globally as climate change drives up the average temperature.

[Sapna Sharma]

We've documented over 4,000 fatal drownings through ice.

[Burley McCoy]

This is Sapna Sharma. She's a global change biologist at York University in Canada. The drowning she's talking about were from 1991 to 2017, and they happened across 10 countries. She says 50% of those drownings are related to air temperature.

[Sapna Sharma]

So basically what that means is that half of those drownings can be explained by winter air temperatures, such that in warmer winters, more people drown.

[Burley McCoy]

When temperatures are hovering right around freezing and freezing, unfreezing, freezing, unfreezing, that leads to more of that weak white ice that we talked about earlier. And it's harder to tell just how safe the ice is.

[Emily Kwong]

And not to mention riskier for people who can't judge whether they'll fall through it or not.

[Burley McCoy]

Right. Going out on the ice. And another thing that makes ice safety trickier to predict is something Hillary calls winter weirding.

[Hilary Dugan]

We'll just have these really cold polar vortex events followed by heat waves. And so winter is no longer this duration of cold weather. It kind of bounces around all over the place.

[Burley McCoy]

So throughout the winter, lake ice is getting more unstable, less safe. Plus ice is forming later and disappearing earlier.

[Sapna Sharma]

Depending upon the extent of greenhouse gas warming, you might expect 10 to 28 days less ice cover by the end of the century. And at current greenhouse gas emission scenarios, we forecast about 5,700 lakes may permanently become ice free within this century.

[Emily Kwong]

Over 5,000 lakes permanently ice free within the century. That is so many. It changes winter as we know it in the north. I guess if there is an upside, it's that if they don't freeze over, it definitely reduces the chances of people falling through. Yeah, but what is at stake for the environment if all that ice is lost?

[Burley McCoy]

Well, for starters, Sapna says when you

[Sapna Sharma]

have less lake ice cover, you have less ice fishing opportunities, recreation opportunities. It matters for winter ice roads. So, so many northern communities especially remote communities. And many indigenous communities actually require the use of winter ice roads to access food, fuel, medical supplies and even social connections in the winter.

[Emily Kwong]

Yeah, ice is an invaluable resource, actually in a lot of places. And it is being threatened by climate

[Burley McCoy]

change, as is lake ice culture, which is less tangible in some ways, but comes with a lot of sorrow.

[Emily Kwong]

Yeah, I bet. That's like a way of life you practice. Burleigh yeah.

[Burley McCoy]

And James Tighe, the festival organizer who we met earlier, hopes that it's also a call to action for change.

[NPR Announcer]

Once people care about something, then they're gonna wanna protect it. You know, things are changing and if there's a year that you can't be on the ice, then people are gonna start to wonder why, and maybe they'll

[Burley McCoy]

ask for a change.

[Emily Kwong]

Burleigh, thank you so much for bringing us this reporting on changing lake ice from your neck of the woods. You're welcome to see pictures of Burley during the lake ice rescue training or at that really cool festival. Check out our show notes. Also, there's so much more reporting to come. We will have another episode on changing lake ice coming out next week. Also, follow us on the app you are listening to, please. Whether that's the NPR app or another one, it really helps us out and means you won't miss out on cool new episodes. This episode was produced by Hannah Chin. It was edited by our showrunner Rebecca Ramirez and fact checked by Tyler Jones. Jimmy Keeley was the audio engineer. I'm Emily Kwong. Thank you for listening to Short Wave, the science podcast from N.

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