Narwhals track Arctic warming in Greenland fjords

Narwhals fitted with satellite transmitters collected more than 2,000 observations that helped researchers track how warmer Atlantic water is entering deep East Greenland fjords, according to a study published Wednesday in Science Advances.

Researchers equipped six of the toothed whales with tags and used them to gather temperature and salinity readings in remote waters from 2017 to 2020. The study said the data helped show Atlantic-origin water beneath glaciers in the Scoresby Sound fjord complex, 350 kilometres inland.

Mads Peter Heide-Jorgensen, a professor at the Greenland Institute of Natural Resources and the study's first author, told AFP the work used “a completely novel technique”.

The narwhals dived to depths of more than 1,500 metres, recording temperature, salinity, depth and position. Researchers used the data to distinguish Atlantic-origin water from polar-origin water.

The study said freshwater from melting glaciers in East Greenland contributes to major Arctic currents, including the East Greenland Current, which helps regulate the Atlantic Meridional Overturning Circulation. Scientists believe a future collapse of that circulation system could bring severe winter cooling in Europe.

The researchers said narwhals can help collect repeated measurements in an area that is hard and costly for ships to reach. Heide-Jorgensen also said narwhals are threatened by warming because their cold-water habitat is shrinking.