Scientists attached transmitters to narwhals in the Arctic. The data they brought back was alarming

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🗞️ Driving the news: Researchers fitted six narwhals with satellite transmitters and tracked them for three years across the fjord system of East Greenland, the largest in the world
• The animals returned more than 2,000 measurements of water temperature and salinity between 2017 and 2020, later combined with ship-based records from the World Ocean Database
• The data shows warm, salty Atlantic water penetrating deep inside the fjords, reaching the fronts of glaciers

🔭 The context: East Greenland is poorly studied because ships require icebreakers and cannot operate there in winter
• Narwhals dive to nearly 6,000 feet, sample the full water column, return to the same locations, and work year-round in darkness
• The instruments weigh under a pound and detach after up to three years. The region also hosts currents feeding the Atlantic Meridional Overturning Circulation, a system scientists fear could collapse.

🌍 Why it matters for the planet: The warm water is melting glaciers from below, at the point where they meet the ocean
• These marine-terminating glaciers drain the Greenland Ice Sheet, so undercutting them accelerates ice loss and sea level rise
• process — Atlantification — is now documented far inside fjords previously assumed to be shielded
Freshwater released here also feeds the currents underpinning AMOC, whose weakening would bring sea level rise along the US coast, colder European winters, and drought in Africa.

⏭️ What's next: Study author Mads Peter Heide-Jørgensen of the Greenland Institute of Natural Resources describes the work as one small piece of a much larger North Atlantic picture, with substantial work remaining to map ocean processes across the region

💬 One quote: "The findings are very concerning… they indicate the rapid melting of the marine-terminating glaciers" — Eric Achterberg, professor at the GEOMAR Helmholtz Centre for Ocean Research Kiel, who was not involved in the study

📈 One stat: Atlantic water was detected more than 180 miles inside the fjord system.

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