The lake at Portage Glacier has transformed into an ice-skating destination

AYESHA RASCOE, HOST:

In the summertime, the Portage Glacier, an hour's drive southeast of Anchorage, is a huge draw for tourists. You can't see the glacier from the visitor's center, so people take boats out onto a lake that sits at the glacier's toe to view it. But in the wintertime that lake freezes over, and locals put on skates and glide out to it. From Portage Lake, glaciologist Aurora Roth has this audio postcard.

AURORA ROTH, BYLINE: It's 8 p.m. at the darkest time of year, but the moon is out, illuminating the mountain peaks that surround this lake. Snow reflects light in all directions. There are about 12 cars in the parking lot of the visitor center. Groups of twos and threes huddle along the shoreline, putting on their skates. It's so cold that the ice crunches under our blades.

(SOUNDBITE OF ICE CRUNCHING)

ROTH: The lake is 3 miles long and curves around a corner towards the Portage Glacier. In the distance, you can see skaters' silhouettes in the moonlight.

It's maybe minus 5 degrees. All the stars are out - Orion, the Big Dipper.

This lake takes a long time to freeze because it's so big and deep. When it does freeze, people in Anchorage post on Facebook. My phone lights up with text messages. And we go skating. I'm out here with Qunmigu Kacey Hopson who also came from Anchorage. It's breathtaking.

QUNMIGU KACEY HOPSON: It's like my friend said when, one time, she ran around and exclaimed, the world is all around me. You just feel like the world is all around you in this really profound way.

ROTH: We're skating towards the hidden glacier, putting half a mile behind us and then another. We skate through a meadow of frost flowers, clusters of ice that look like glittering chrysanthemums.

(SOUNDBITE OF ICE CRUNCHING)

ROTH: I'm a glaciologist, and I grew up in Alaska, where glaciers feel like our neighbors. Portage Glacier is among Alaska's best known, and its story is one of dramatic change. A hundred years ago, the glacier went all the way to the parking lot. But around 1914, a lake naturally started to form at the base of the glacier, and that started a chain reaction where more and more pieces of ice calved off the glacier into the lake and melted away. Warmer air temperatures from human-caused climate change eventually played a role, as well. In a single century, the glacier jumped back 3 miles.

(SOUNDBITE OF ICE CRUNCHING)

ROTH: As we skate towards the glacier, we're skating through its past, following its path of retreat. We turn the corner, and then finally, we see it - a jumble of ice sloping back into the mountains. We don't get too close because big ice blocks could fall off the glacier onto the lake ice. It has a winter blanket of snow in its upper reaches, but there's all of this blue ice exposed that, even in the moonlight, you can tell it's blue, and it's just stunning.

People often ask me if studying glaciers makes me sad. Across Alaska and other places, they're melting rapidly because of climate change with dire global consequences. It's true. There's a lot of grief for me in this work. But what allows me to keep doing it are nights like this when time stops and all I'm left with is awe. For NPR News, I'm Aurora Roth on Portage Lake. Transcript provided by NPR, Copyright NPR.