ADRIAN FLORIDO, HOST:

East Greenland is home to the world's largest fjord system, where glaciers meet the Arctic ocean. And the waters there are sometimes so calm, they look like a mirror.

MADS PETER HEIDE-JORGENSEN: And then there's some few icebergs that are floating around and some seals and some narwhals that are in the water.

FLORIDO: This is Mads Peter Heide-Jorgensen of the Greenland Institute of Natural Resources. He and other scientists are studying glaciers in East Greenland because they're key to understanding human-caused climate change in the Arctic and rising sea levels around the world. NPR's Rachel Carlson takes it from here.

RACHEL CARLSON, BYLINE: East Greenland is of particular interest to scientists who study a phenomenon called Atlantification. Warmer, saltier Atlantic water mixes with chilly Arctic water and contributes to melting ice. Mads Peter Heide-Jorgensen is one of these scientists. He says East Greenland is icy, remote and a hard place to do research.

HEIDE-JORGENSEN: The issue here has been that there's very little data in the past from this region. It's not a place where many oceanographers have ventured into.

CARLSON: That's why for a new study out this week in the journal Science Advances, Jorgensen and his team collaborated with some very special divers - six narwhals outfitted with recording devices to measure the temperature and salinity of the water. And Jorgensen says the measurement showed the water near East Greenland glaciers is getting warmer and saltier, both signs of that process called Atlantification. He was surprised by how far the Atlantic water seemed to travel.

HEIDE-JORGENSEN: Even the most remote glaciers in the inner pass of the Scoresby Sound fjord system were also affected by Atlantic water.

CARLSON: He says this is a sign that the Arctic is changing and that warming seas are even impacting some of the hardest to reach areas. But Jorgensen says he's hopeful this study will lead to more data collection from East Greenland and beyond, with a little help, of course, from the narwhals.

Rachel Carlson, NPR News.

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