This story was originally published by Grinding and appears here as part of the climatic table collaboration
When marine biologist Mads Peter Heide-Jørgensen began studying the boreal waters around Greenland 40 years ago, an inflatable raft took him across vast expanses of polar ice, with narwhals and walruses frequently passing by. The amazing blue sea ice seemed almost inviolable in its grandeur.
But with Greenland reaching its highest temperatures in the last 1,000 years, the scenario is changing. Arctic sea ice, which is responsible for keeping polar temperatures cold, is declining rapidly. The oldest and thickest of hers has decreased by 95 percent during three decades of global warming.
“There is a whole beautiful landscape that used to be there,” said Heide-Jørgensen, a researcher at the Greenland Institute of Natural Resources. “Today, we can see that all the ice is gone.”
So are an increasing number of the creatures that lived among it. Inuit communities are seeing little to no evidence of endemic species such as narwhals and walruses that Heide-Jørgensen became familiar with. Instead, they are finding animals native to more southern waters, such as mackerel, bluefin tuna, and many types of cetaceans, all of which are attracted to the warm waters and abundant prey.
Visual observation and remote sensing leave Heide-Jørgensen and fisheries biologist Brian Mackenzie with little doubt that potentially irreversible regime change – a change from one stable ecological condition to another is taking place. Record numbers of dolphins and humpback and fin whales suggest a turning point in the marine ecosystem off the east coast of the world’s largest island. This climate-driven change not only means that weather and climate events thousands of miles away can affect local conditions in unexpected ways, it also creates the potential for cascading effects across entire ecosystems.
“It has a very specific driving force for the tipping element, which is sea ice.” said Heide-Jørgensen, who attributes the regime change primarily to a significant decrease in summer sea ice arriving from the Beaufort Sea.
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That body of water, located along the northernmost coast of Alaska, generates the sea ice found off the coast of eastern Greenland. It is carried there over several years by winds and currents. For Greenland’s native marine species, ice regulates temperatures by reflecting sunlight and provides critical habitat and nursery grounds for animals, invertebrates, and algae.
As the sea tern flies, the Beaufort Sea is about as far from these waters as Anchorage, Alaska, is from Portland, Oregon. “It’s a huge distance,” Heide-Jørgensen said. She noted that the scope of what is happening in Greenland shows that the effects of climate change are certain and far-reaching, affecting ecosystems for thousands of kilometres. “It goes way beyond what we originally thought. Local systems can be severely affected by something so far away, which is a lesson learned.”
While many studies have shown regime changes in other marine ecosystems around the world, little has so far been revealed about such changes in the Arctic. The researchers note that the process that drove the radical change likely began 10 to 20 years ago when temperatures began to rise more dramatically. Thanks to the explorers of the 19th century.Greenland ice records date back to 1820 and help reveal weather patterns and effects.
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“It contributes to the overall evidence base for how climate change is affecting life in the oceans,” said Mackenzie, a professor at the Technical University of Denmark. “Now there are many studies that show changes in distributions, changes in food webs, etc. Not many for the Arctic or in remote places like this. And so it is contributing to the pattern that we have been seeing in the scientific community.”
Humpback whales, usually found off the coast of New England and Newfoundland and in northern Scandinavian waters, now migrate by the thousands along the eastern coast of Greenland. Fin Whales, also commonly seen offshore in the North Atlantic, are also becoming more common. And while this change isn’t necessarily bad for opportunistic cetaceans, who can adapt to a certain threshold of oceanic changes, it puts enormous pressure on endemic species like the narwhal. Researchers suspect that the native creatures are moving north as the water warms and interlopers arrive.
Newcomers like whales, which require a large amount of food to sustain themselves and migrate thousands of kilometers, now consume more than 1 million tons of food per year, outpacing other animals. “There are big ecological implications for local biodiversity and species interactions,” Mackenzie said. “Particularly in competitive predator to prey relationships.”
Marine species are not the only ones to experience these ramifications. Changes in the distribution of species, especially fish, could reshape commercial fishing.
Bluefin tuna had never been recorded off the east coast of Greenland before 2012, but have been recorded every year since. “We got some reports from Greenland fishing crews that they had caught some bluefin tuna as bycatch,” Mackenzie said. “And we could see that the temperature in the area had increased considerably compared to previous years. The thermal habitat expanded and that’s one of the reasons we think tuna started to show up. The mackerel itself had not been seen in Greenlandic waters before 2011, and we believe the tuna more or less followed the mackerel. With changes like this, there are likely to be multiple effects throughout the food web, especially at lower trophic levels.”
Unless ice exports from the north increase and temperatures cool, this new regime is likely to become permanent. “It would require the unlikely and substantial reversal of current warming, and several years to reverse the trend with little multi-year ice in the Arctic Ocean,” Heide-Jørgensen said. “No climate agreement seems to cover that at the moment.”
Given the rate of global climate change, the Arctic Ocean could, within our lifetimes, record its first ice-free summer. Some studies suggest that may happen within a few decades. “Forty or 50 years ago, that concept would be unthinkable,” Mackenzie said. “But it looks like it’s going to happen. And if that happens, it would mean even bigger changes to the food web and ecosystems up there.”