This August 2017 photo provided by The Greenland Institute of Natural Resources shows a narwhal being tagged by scientists in Hjornedal, Scoresby Sound, Greenland. In a study published in Science Advance on Wednesday, researchers equipped six narwhals, sometimes called the "unicorns of the sea," with satellite transmitters, and had them explore remote East Greenland waters. Between 2017-2020, these "unconventional collaborators" retrieved more than 2,000 invaluable observations of temperature and salinity that helped show how warm Atlantic water is penetrating deep into the region's fjords and intensifying glacial melt, which in turn has impacts for critical global weather systems. (Photo by The Greenland Institute of Natural Resources / Handout / AFP via Getty Images) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / Mads Peter Heide-Jørgensen, The Greenland Institute of Natural Resources" - HANDOUT - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS