Rapidly warming Alaska is already a poster child for climate change, from its vanishing sea ice to its thawing permafrost. But over the last three years, the state’s northwestern coast has experienced a series of unusual climate-related changes—remarkable even for the long-altered Pacific Arctic.
Beginning in 2017, a combination of abnormally high temperatures and unusually strong, southerly winds swept the Bering and Chukchi seas. An alarming cascade of ecological consequences ensued—record-low sea ice, shifting algae blooms, migrating fish populations and sudden seabird die-offs were just a few.
“Most of my own research is with people living in the coastal communities, so talking to them and hearing about what they’re seeing,” said Henry Huntington, an independent Alaskan researcher and consultant. “And they saw some very unusual things, and things that struck them.”
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“Ridiculous” water temperatures and unstable sea ice were among the most common complaints raised in interviews with coastal residents, Huntington noted.
“Adding to that, what we’re hearing from folks on the research cruises, it just became apparent that things were really a lot different from what any of us expected,” he said.
Conditions appear to be returning to a more typical state for now. But some scientists say the episode could offer a valuable glimpse into the region’s future under climate change.
In a paper published this week in the journal Nature Climate Change, nearly two dozen Arctic experts—led by Huntington—describe the dramatic changes underway off the coast of Alaska. And they warn of the potential for a possibly permanent ecosystem transformation if temperatures there continue to climb.
Beginning in 2017, temperatures soared in and around the Bering and Chukchi seas. And strong winds blowing from the south began to pick up, pushing the sea ice cover farther north.
Sea ice cover was low to begin with in January 2017, and remained below average for the rest of the winter. In May, as the spring melt began to set in, reports suggest there was already an unprecedented amount of open water off the coast of Alaska. By November 2017, the region’s sea ice cover had hit a record low for that time of year.
The unusual conditions spilled over into the following years. In February 2018—a time when Arctic sea ice is typically reaching its maximum extent—there was no ice at all observed in the Bering Strait. Water temperatures in the Bering Sea soared again in the summer of 2018. There was minimal sea ice again in February 2019.
Meanwhile, the local ecosystem was undergoing a sea change—literally.
With less ice in the way, more water was able to flow north through the Bering Strait, carrying extra heat and nutrients with it. In the northern part of the Bering Sea, plankton explosions occurred early and extensively in the spring.
In the southern Bering Sea, on the other hand, the spring algae bloom was delayed. That’s likely due in part to the low sea ice cover and a lack of freshwater input to help fuel the bloom—typically, melting sea ice would help supply this fresh influx.
At the same time, fish were redistributing themselves around the ocean. Species that prefer warmer waters, such as salmon, increased significantly. And cold-loving species like walleye pollock, Pacific cod and northern rock sole began moving into northern waters where they’re not usually found, likely in search of cooler waters.
Seabird populations also began to shift, probably in response partly to changing plankton and fish distributions.
Plankton-eating auklets, for instance, increased in the northern Bering Sea in 2017 and 2018, but declined in the Chukchi Sea. Scientists recorded several seabird die-offs, involving multiple species, in the Bering Sea during this time period. Fish-eating murres and kittiwakes, on the other hand, increased in the Chukchi Sea.
And some of the region’s most noticeable residents became more conspicuous.
Walruses spend much of their time out on the sea ice, but will retreat to shore if the ice melts. In recent years, the northwestern Alaskan community of Point Lay has made headlines as tens of thousands of walruses hauled out on the beach—driven there by unusually low sea ice conditions in the Chukchi Sea. In early August 2017, Point Lay experienced its earliest haul-out event yet.
Some of these outcomes might have occurred after just one abnormal season. But the kind of large-scale ecological cascade that occurred between 2017 and 2019 was largely the product of back-to-back years of low sea ice, said NOAA scientist Janet Duffy-Anderson in an interview with E&E News.
“It’s not how the ecosystem responds to one year—it’s how it cumulatively responds to multiple years in a row,” she said. “That’s when you get these cascading, multiple trophic-level effects—plankton, zooplankton, fish, birds mammals. It takes a couple of continuous cycles.”
‘Blink and you miss it’
For now, the shifts observed between 2017 and 2019 don’t necessarily appear to be permanent.
Sea ice extent seems to have rebounded back to more typical conditions in the beginning of 2020, said Elizabeth Siddon, a scientist with NOAA’s Alaska Fisheries Science Center. That sets the region up for a kind of “reprieve,” she noted, which may allow the ecosystem to return to its previous state.
But the events of the last few years could offer some clues about how the Pacific Arctic might respond to future climate change. Temperatures in the region are expected to continue rising, and some models suggest that the kinds of anomalous wind patterns observed in 2017 through 2019—which helped drive the sea ice farther north—may strengthen as the climate warms, Siddon noted.
If that’s the case, the conditions observed over the past few years could occur more frequently, last for longer periods of time or even become permanent in the Pacific Arctic. The recent back-to-back abnormal years could provide a glimpse of how the ecosystems of the Bering and Chukchi seas respond—at least in the beginning—to extended periods of warm waters and low sea ice.
“These changes that are documented over two years, these are the kinds of things we can potentially expect as these open-water periods in the wintertime get more and more frequent,” Duffy-Anderson said.
Still, it’s not necessarily a perfect analogy for the future. Whether these kinds of shifts will last in the long run, or how the ecosystems might evolve under more intense climatic changes, is a matter of debate.
For instance, the recent observations suggest that some species of fish respond to warming waters by migrating north. That may hold in the short term—but whether they’re capable of surviving there in the long term is uncertain. These species may be adapted to the rising temperatures that are creeping into the higher latitudes, Duffy-Anderson pointed out—but not necessarily to the low-light conditions that come with the dark Arctic winter.
“How will these more southerly affinity species adapt to an ecosystem where some of the parts are similar and some of the parts are different? That’s an unknown,” she said.
In general, most researchers expect that the shifting Arctic will include both “winners and losers,” Siddon suggested. Some species may flourish in a warming Arctic. Some could disappear entirely.
“We don’t know that everything is going to be a loser,” she said. “We just don’t know yet, with two years of low sea ice, what that’s going to mean. One of the most important things I try to keep in mind is we can’t assume stationarity in these relationships—that the species, themselves, can adapt as conditions change.”
For now, the greatest certainty about the Arctic may be simply that it will look different than it does today—just as it already looks different now than it did several decades ago. And in rapidly shifting ecosystems, like those in the Pacific Arctic, there’s an opportunity for scientists to study the progression of climate change in real time.
“If we miss the chance to monitor and to pay attention now, we can’t go back in time and figure out what had happened,” Huntington said. “The speed at which things are changing is now so high that we’re getting into the sort of ’blink and you miss it’ territory. We can’t go up and do a survey every five years; that’s not enough. Things change so much in the space of a year or two, as we’ve seen, that we need to be paying close attention.”
Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.