Jakobshavn is Greenland's biggest glacier. And over the past 20 years, it's receded dramatically. Play NOVA's Polar Lab to learn what's behind that change.
What’s Causing Greenland’s Biggest Glacier to Melt?
Published: February 25, 2020
David Holland: The waters all along the west coast of Greenland were cool right up until 1997. Suddenly the waters on this coast, and in this fjord, had suddenly jumped, and it’s been warm ever since.
Caitlin Saks: And since 1997, the glacier has retreated significantly—due primarily to warming ocean waters.
David Holland: The ocean seems to be in control of this 20-year retreat.
Caitlin Saks: Something caused the waters around Greenland to warm up quickly, even faster than the Earth’s oceans as a whole. And while scientists are still debating why it happened, David Holland and others think it was a shift in a big current called the Gulf Stream that brings warm water up from the south.
David Holland: Generally, it carries warm water from the United States towards Europe, the bulk of it. In 1997, a major piece of it headed off towards Greenland.
Caitlin Saks: The result was a rise in water temperature of about a degree. You’d barely notice that in the air outside. But here in Greenland’s waters, it matters a lot. Scientists are working out how much of a role climate change played in this ocean warming. But one thing is for sure—warmer waters melt Jakobshavn from below, leading to its rapid retreat. And it’s not just Jakobshavn and Greenland.
David Holland: What’s far more important is the exact analogue of this is going on right now in Antarctica where the stakes are much higher.
Caitlin Saks: Because there’s a lot more ice there.
David Holland: And the same process could lead to major sea level change.
Caitlin Saks: The Jakobshavn Glacier ice that’s flowing into the fjord used to sit on land. That’s why it’s adding to rising global sea levels as it melts and falls into the ocean. But sea-based ice across the Arctic is also in decline. And the impact of changing glaciers and ice cover are already being felt.
Hosted by: Caitlin Saks
Production by: Ari Daniel & Lorena Lyon
Camera: Emily Zendt
NOVA Labs Editorial Director: David Condon
Additional Visuals: Mitch Butler, NASA | Goddard Space Flight Center Scientific Visualization Studio, Pond5, Shutterstock
© WGBH Educational Foundation 2020