Researchers have used narwhals—often called the "unicorns of the sea" due to their long, spiral tusks—to monitor changes in Arctic waters and track the effects of global warming. In a study published in Science Advances, scientists attached satellite transmitters to six narwhals in East Greenland between 2017 and 2020. These animals collected over 2,000 data points on water temperature, salinity, and depth, revealing that warm Atlantic water is moving deeper into Arctic fjords. This warming is accelerating the melting of glaciers, which can influence global weather systems. Mads Peter Heide-Jorgensen, a professor at the Greenland Institute of Natural Resources and lead author of the study, explained that the team used a groundbreaking method. The narwhals dove to depths of over 1,500 meters, sampling entire water columns and collecting data on temperature, salinity, depth, and location. This information was used to determine the water's potential density, helping scientists identify whether it originated from the Atlantic or from polar regions. One of the study’s key findings was that Atlantic-origin water was found deep beneath glaciers in the Scoresby Sound fjord complex, 350 kilometers inland. Freshwater from melting glaciers in East Greenland flows into two major Arctic currents. The East Greenland Current is especially important because it plays a role in the Atlantic Meridional Overturning Circulation (AMOC), a vast system of ocean currents that helps regulate Earth’s climate. Scientists warn that if the AMOC were to collapse, it could lead to significant cooling in Europe, causing harsher winters. Understanding how Atlantic water is changing the composition of East Greenland waters—often called "Atlantification"—is critical, but the remote and extreme environment has made traditional research methods costly and difficult. In the past, scientists relied on crews aboard ships to collect water samples, but this approach is limited by the harsh Arctic conditions and the high cost of icebreaker ships, which are needed to navigate frozen waters. These vessels are also risky to operate near glaciers, where large ice chunks can break off—a process called calving. More recently, electronic sensors have been used, but they are typically deployed only during the summer when the sea is ice-free. The narwhals, however, proved to be effective data collectors. They naturally return to the same areas, allowing scientists to gather repeated measurements over time. The researchers expressed enthusiasm about the collaboration, calling it a demonstration of how creative methods—like working with narwhals—can transform oceanographic research. However, Heide-Jorgensen noted that narwhals are struggling with the effects of climate change. As the Arctic warms, their habitat is shrinking, and they may eventually need to move northward to stay near the cold water they rely on. While the narwhals are valuable collaborators, they are also among the "losers" in the climate change scenario.