You’ve spent so much of your life in the northern and southernmost extremes of our planet. What draws you to high latitudes?

In our planet’s highest latitudes, you get to places that are beyond wilderness. The purity of the landscapes draws me. They’re so wild. You can’t compare them to anything else. And then there’s the wildlife. In Antarctica, the wildlife’s in the water and on the coastline. But in the north, it’s everywhere.

How have the polar regions changed over the decades that you’ve been visiting them?

The first 25 years, prior to 1990, we had what I would describe as normal winters. Since then, we’ve seen major openings in the Arctic Ocean ice cover, then in 2007 a major breakup of the ice during the Arctic summer. All of the ice shelves I’ve traversed are melting. Many of them are gone: Ward Hunt, Northern Ellesmere, and Antarctica’s Larsen A. In 2002, I saw the news that the Larsen B ice shelf was disintegrating. It had taken me 14 days to cross it. To read that it had broken up, was gone—that changed my life. I started a non-profit, Climate Generation, to educate the public about what was happening. We do lots of work in climate and energy policy, and we’ve been able to help steer my home state of Minnesota in the right direction.

Tell me about the film you’ll be making while you’re aboard the National Geographic Explorer.

I decided to make a film about the breakup of the ice shelves. I’ve been telling this story for many years. It’s not a doomsday message, but people have to look at the reality of what’s happening. I want to create a film to tell this story, and we’ll be gathering footage while I’m at sea with National Geographic Expeditions.

Would you say the first step was the hardest on many of your extreme journeys?

I always get asked how I do the sorts of things I do. I say you can too. There are all sorts of excuses for not doing the tough things, but you just have to put on your boots and do it.

What was your inspiration for devoting yourself to a life of exploration?

For a lot of young people, National Geographic gave us the pictures around which we wrapped our dreams. I played ice hockey; that was the biggest sport where I lived. When I was 13, I traded my hockey skates for a sled full of National Geographic magazines. We bargained back and forth, a friend and I, and I’ll never forget the day in February when I struck a deal and pulled a sled full of magazines into my living room.

Through National Geographic, I took my kayaking trips, my climbing trips. I ended up getting your La Gorce Medal and becoming an Explorer-in-Residence, writing three articles for the magazine. It shows me the power of having a dream as a kid and achieving it. If you follow your heart, working 16 hours a day is a pleasure.

Travelers will have the opportunity to journey to Antarctica with you in December. Why should they come?

Antarctica is unlike anything else you’ll see in your lifetime. You’re inspired by it. Once you visit, you can never forget it.