When sea ice failed to cover Alaska’s Kotzebue Sound for the first winters in recent memory, the people who live in the area raised questions about what those anomalously warm seasons meant for the future.
Among the questions raised during the winters of 2018 and 2019: Why was there so little ice, why was the ice that existed so thin? What were the impacts on ringed seals, which create snug caves in the snow atop the ice to protect their young?
Two studies conducted in a project that teams Indigenous residents with university scientists have now provided some answers.
While ocean heat moving north through the Bering Strait is the major factor, it turns out that river water is also an important factor in the formation and quality of ice — or the lack thereof, according to one study published in the journal JGR Oceans.
Water draining into Kotzebue Sound from the rivers is alternatively helpful and harmful to ice formation. In the fall, the runoff of freshwater from rivers is generally colder than the sound’s saltwater and thus helps speed up the winter freeze. But in the spring, that freshwater is warmer than what is in the sound, so it speeds up the seasonal melt.
What ice did exist was thinner than anything in recent memory, with some ominous implications for both ringed seals and people, according to another study, published in the Journal of Glaciology.
Such thin ice was easily flooded, which in some places doomed the layer of snow resting atop. That was an ominous turn for ringed seals’ lairs dug into the snow. Flooding that inundated the snow layer and then froze, did thicken parts of the ice layer, but the flooding also invaded the space that ringed seals need for the snowy dens they build to bear and shelter pups, the study found.
That revelation was borne out through experience. Study leader Andrew Mahoney of the University of Alaska Fairbanks and his colleagues found one seal lair in such a state — dug into snow that had been reformed through flooding into ice, but still apparently in use.
“The main reason we identified snow flooding as something important to look into is that we saw signs of it pretty much everywhere we went and it was clearly relevant in the contexts of both ice mass-balance and seal habitat,” Mahoney said by email.
That was driven home when they found an open ringed seal den that had a shelf of ice about 38 centimeters below the waterline.
“After some initial puzzlement, we realized this shelf was the original ice surface that had been excavated to form the den, but subsequently submerged by the weight of snow,” he said. Next to the lair, the team retrieved an ice core in which the upper 38 centimeters was “composed of snow-ice,” the frozen, flooded snow.
Both studies are products of the Ikaaġvik Sikukun project, which is funded by the Gordon and Betty Moore Foundation, an organization willing to back a new way of doing Arctic science.
Normally when scientists apply for grants from the National Science Foundation or other government entities, they have to present well-structured plans, including hypotheses and experiment procedures. What is left to do, once those projects are funded, is carrying out the planned work, said Chris Zappa, an oceanographer with Columbia University’s Lamont-Doherty Earth Observatory and a key member of the Ikaaġvik Sikukun team.
“Everything is mapped out,” said Zappa, a co-author of both studies. “Essentially, you go and do something that’s really low risk.”
In contrast, the Ikaaġvik Sikukun comprises what would be seen by traditional funders as risky projects, something the Moore Foundation was interested in supporting, he said.
The outside-the-community I the Ikaaġvik Sikukun scientists spent the first year of the five-year project not collecting data but simply listening to Kotzebue residents and learning what they wanted to study, Zappa said.
One of the major concerns, it turned out, was about the ice melt that bridges two hunting seasons important to the region’s Indigenous people, he said.
After the melt, bearded seals, ugruk in Iñupiaq, swim into Kotzebue Sound and rest on ice floes, where they are pursued by hunters in boats. The bearded seal hunt — and the way that climate change has shortened its duration — was the subject of the first published study produced by the Ikaaġvik Sikukun project.
The season to hunt for ringed seals takes place before the melt. “The hunters need the ice there for the natchiq, the ringed seals, because they can get out to the little breathing holes. The natchiq come up through the breathing holes,” Zappa said.
One overarching question has emerged in the region: Did the two anomalously warm winters make a permanent change in the marine environment?
Zappa said there is not yet evidence that those years created any kind of tipping point that changed the marine regime.
“Right now I would say that these are two kind of anomalous years in the natural variability of the decline,” he said.
It will take several more years to know whether those two years left permanent effects, he said. “In hindsight, you could say, ‘Oh yeah, that was the tipping point. But you don’t know until you have a number of years of data.”
The Ikaaġvik Sikukun project aims to do more than provide published scientific studies. There is a legacy aspect to the program, intended to include lasting community relationships and
One example of the legacy work is the inclusion of a filmmaker in the project, Sarah Betcher of Farthest North Films. Some short films are already available for viewing, and there is a documentary going through final review, Zappa said.
Another legacy could be a system of simple monitoring stations upriver to help assess the safety of traveling over sea ice. “We could potentially use that to predict when the ice breakup will happen, or when it would be unsafe,” Zappa said.