What’s the difference between sea ice and an ice shelf? As far as landscape features near Ross Island, Antarctica go, there is little difference in appearance between the two. However, there is a big difference as far as stability goes.
Last weekend, McMurdo Ice Marathon participants skied and ran on the McMurdo Ice Shelf (pictured above, groomed for vehicle and recreational travel). It’s late-summer now in Antarctica, and the ice shelf doesn’t melt…but it could possibly melt in the future if global temperatures continue to rise. Generally, an ice shelf is the thick layer of ice formed by an ice sheet or a glacier that bridges the area where a frozen continent, such as Antarctica, meets the sea. There are lots of glaciers around here…especially at the base of Mount Erebus (below), the world’s southernmost active volcano.
Whereas an ice shelf is a thick, floating platform, sea ice is the thinner, non-permanent ice that extends from the ice shelf and floats like a crust on the water below it. Early season at McMurdo, the sea ice is thick enough for planes to land on it, which is nice logistically because the sea ice runway is only a fifteen-minute shuttle ride away from town. But by the first week in December, the landing strip gets moved onto the ice shelf, and it takes forty-five minutes to reach by shuttle.
Penguins, such as the Emperor Penguin above, aren’t sighted very often at McMurdo because they live in breeding colonies, none of which are super close to town. Emperor Penguins, however, are known to make long journeys to mate and feed offspring. They’re inclined to travel, these birds, but even so, it’s exciting to see them in our area—this one sighted on the McMurdo Ice Shelf near the Pegasus late-summer airfield.
One of the things I appreciate about being able to ski out on the sea ice or the ice shelf surrounding Ross Island is the chance to feel like I’m out in the wide-open. Sometimes it feels crowded in town with our population of 1,000 people crammed into little spaces and eating together in the galley. Our personal lives and professional lives sometimes get too intertwined. But when I’m outside with so much flat, open space around me, my worries melt into the surroundings.
You can run or ski away from your worries anywhere in the world. But doing it here, with a view of Mount Discovery looming across the great expanse of the McMurdo Ice Shelf, makes those worries seem so much smaller to begin with.
Traci skiing: Stan Schweitzer; Mount Erebus: Matt Truch; all others Dan Costa. Thanks marathon volunteer photographers!