Die Schwanzflosse eines Buckelwals ist am 02.08.2017 im Nuup Kangerlua Fjord, Grönland, zu sehen. Foto: David Goldman/AP/dpa +++ dpa-Bildfunk +++

When a water fountain splashes out of the waves off the coast of Greenland, a whale is just blowing stale air upwards. The huge and often ancient bowhead whales, the narwhals with their distinctive tusks and the beluga whales with their strikingly light skin are perfectly adapted to life in the icy waters of the far north – and therefore, like the polar bears on the sea ice, face considerable problems because of the fact that climate change is heating up the northern polar region.

By the year 2100, these species could be native a few hundred kilometers further north than they are today, estimate Philippine Chambault from the Greenland State Environmental Research Institute in Nuuk and the University of California in Santa Cruz and her team. According to their study, recently published in the journal Science Advances, the habitat of whales in the Arctic is likely to shrink by an average of 25 percent in summer.

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Even if these estimates are still quite rough and therefore relatively uncertain, they show a clear trend: The whale populations in the far north are under severe pressure. This calculation was based on data sets from 29 beluga whales, 71 bowhead whales and 129 narwhals that swam through the waters around Greenland equipped with a small device between 1993 and 2020.

The mini devices revealed the whereabouts of the respective animal and thus also its migration routes. Philippine Chambault compared this movement data with the values ​​that climate models spit out for the state of the marine regions in the far north in 2100.

Where, then, might whales find similar surface water temperatures, salinity, and other characteristics to which they have been accustomed for the past three decades? So how large could their habitat be after climate change altered conditions in the polar regions? In summer, the three whale species should therefore swim around 243 kilometers further north than today. And even in winter, the habitat would be about 121 kilometers closer to the pole. However, not only does climate change have different effects in the individual areas, but also the different whale species react differently to such influences. The white whales, often also called “Beluga”, currently live mainly along the coasts in the north and south of the huge Canadian Baffin Island, which lies off the North American mainland and the Hudson Bay.

If mankind manages to limit the temperature rise on earth to less than two degrees, the homeland of the belugas would still migrate significantly north by 2100 and the animals would lose almost three quarters of their habitat at 71 percent in summer. If, on the other hand, humanity continues to use huge amounts of coal, oil and natural gas, the study even calculates a loss of 88 percent of the beluga summer waters.

As dramatic as these numbers sound, the reality could be even worse. Thus, the belugas live in many groups, each of which mostly swims in the summer exactly in the area in which it already spent August and September in the previous years. But what happens when the animals in this traditional homeland get too warm and perhaps don’t find enough to eat? Will they persevere there to the end? Or maybe some animals dare to move to a new habitat with better conditions? How many belugas would follow these pioneers? Whale hunting may provide an indication of the behavior of beluga whales in the face of climate change: the species was practically wiped out off Spitsbergen and has not returned to this day.

Philippine Chambault and her team also determine significant losses for the bowhead whales, which live near the coasts of Baffin Island, on the coast of northeastern Greenland and north of Svalbard and across to Franz Josef Land at the pack ice border: By the year 2100 28 percent of their summer areas could disappear if the two-degree climate target is met. If not, the losses could be as high as 68 percent.

The study also shows a loss of a similar magnitude for the narwhals, with 31 percent when the two-degree target is reached and 66 percent when this mark is exceeded. At least for the groups living on the coasts north of Baff Island. For the same species, however, climate change on the east coast of Greenland could bring a significant improvement. If the two-degree target is met, the animals could find 85 percent more living space, and if this mark were broken, it would even be 105 percent.

However, Philippine Chambault and her team point out that this species is particularly sensitive to climate change. After all, narwhals mostly live near sea ice, which is expected to have largely disappeared from the Arctic Ocean by 2060, at least in the summer. On top of that, like the belugas, the narwhals usually stay true to their location. Therefore, nobody knows whether the unicorns among the whales actually dare to jump into the Arctic Ocean. After all, the water is quite deep there, which would suit the narwhals, who usually hunt for their prey more than 300 meters below the waves.

In this context, Philippine Chambault and her team point out a weakness of their study, in which they mainly take into account the surface temperature of the water. However, narwhals usually hunt in the depths – and spend a crucial part of their lives there. However, the researchers hardly took the conditions at depth into account because very little is known about them. Researchers also know very little about the diving depth and thus the hunting grounds of bowhead and beluga whales. These species could therefore face more problems in the future than the computer simulations suggest.

In addition to climate change, other problems are likely to worsen the situation of whales in the Arctic in the future. If the ice melts, more mineral resources will be searched for in the far north. This would mean that more ships would pass through this region, which would increase pollution and, above all, generate more noise. However, this could disrupt the whale’s sensitive hearing organs, on which they are often particularly dependent. The future of bowhead whales and narwhals, as well as the belugas, could look even bleaker.