Hauling a pair of sleds loaded with more than 300 pounds of gear (including 11 pounds of chocolate) across a moving landscape of sea ice has always made the challenge of human-powered travel to the North Pole precarious at best. But disappearing sea ice—down from 12 feet to four feet thick—makes for even more dangerous terrain. Plus, fewer pilots are willing to land on that thin ice, and bad weather has narrowed the window of when they can even make an attempt. So when Eric Larsen and Ryan Waters skied, snowshoed and swam from Canadian soil to the North Pole in 2014, they knew that their expedition might be the last of its kind—both an exclamation mark and a swan song, as Larsen puts it. His latest in a multimedia effort to tell the story of this disappearing place is a book, co-written by EO contributing editor Hudson Lindenberger: On Thin Ice: An Epic Final Quest into the Melting Arctic. We got him to pause while planning a promotional tour of REI stores to answer a few questions.

You’ve long combined this notion of polar exploration with educating people about climate change. Why?

My background is in environmental education, so I didn’t just come into the adventure world and try to protect the environment as an add-on. I was trying to get people interested in this issue and I want to find the most compelling ways to tell those stories. So I realized, from an educational perspective, that adventure could have a good connection to places and the issues that are going on there, especially with the Arctic. It’s a place that’s so abstract for most people, we kind of need that physical human drama to help better understand it. And, obviously, I love the adventure too, and I like the physical and mental challenges and I want to be able to continue it do it. If there’s no ice, it’s not possible.lastnorth-00506What does a polar explorer do when you can’t go back to the North Pole?

Yeah, exactly. I’m still trying to figure that out. I’m still focused on the same mission of all the trips that I’ve done previously, which is going to these cold places. What I’m able to do now is cast my reach out a little farther than the North Pole, because if you look at any of these iconic cold spots—the Patagonia ice cap, Siberia, Nepal, Mongolia, back to Arctic Canada, but not the Arctic Ocean—these are all places that are changing and I almost feel a greater desire to keep going on this mission because we’re in a race against time. It’s no longer about being the first person to these places; now, it’s about being the last, and it’s almost like going out and making sure we understand what we have right now. It’s like going out and seeing the last Dodo bird or the last passenger pigeon.

Has anyone been able to repeat the trip you and Ryan completed?

No. I think there are some guys who are looking at going this year. I hope they can do it quite honestly, but I’m realistic. When I really dig down in my heart of hearts, I’m convinced that our trip will be the last full North Pole expedition, and that’s not necessarily a badge I want to be wearing.

How has becoming a husband and father affected your exploration goals?

It’s changed them a lot. When we were in Nepal last year, Ryan and I were on this knife-edge ridge, trying to do it, and I could see Everest way off in the distance. It was just really sketchy. I do mountaineering, but I’m not the most talented and hardcore mountaineer, so it was pushing my comfort level pretty substantially, and I just felt like, “What am I doing here? I have two kids. That’s my most important job.” So it’s something that’s constantly on my mind. Ryan probably gets a little sick of me looking at pictures and video. But then I got back from Nepal and I was home for a week and a half and sent Ryan a text message: “I’m ready to go again.” So it’s a hard thing to balance. I love being a dad more than I would ever have possibly imagined. It’s a lot like an expedition because you’ve got to keep on top of everything all the time, and I like that. But I also know that big trips are part of who I am.

Do you have any hope of getting to take your kids to see the Arctic?

Oh yeah, I do. But they may not be able to see those places like I have. They may go there on a boat. It may be nothing but water.