The ‘Ice Tsunami’ That Buried a Whole Herd of Weird Arctic Mammals

Pity the musk ox.

A herd of musk ox
Joel Berger

The biologist Marci Johnson spent the daylight hours of Valentine’s Day 2011 in a helicopter, high over the Alaskan coastline, searching for musk oxen.

It was part of her job. Through the winter, she regularly went to check in on animals that she and her fellow researchers had outfitted with radio collars the year before. On this particular flight, she quickly found what she was looking for: a pack of 55 musk oxen moseying along in the snow. From the helicopter, Johnston could detect all four radio collars chirping happily—the “alive” signal.

She returned home to Kotzebue, Alaska, where she lived and worked as a biologist with the U.S. National Park Service. Winter wore on. A blizzard roared in off the Arctic Ocean, bringing whiteout conditions and winds between 60 and 100 miles per hour. What had been most unusual, though, was the storm surge—she remembers meteorologists warning local residents not to tie up their dogs close to the beach.

A few weeks later, she flew out again to check in on the musk oxen. But when she and the pilot flew over the same lagoon, they didn’t see the amiable shaggy dots—they didn’t see anything.

“We looked down out of the plane, and all there was was white,” she told me. “It was just ice. There was normally a group of 50-plus black dots.” At the same time, the radio-collar detector began emitting a series of fast, angry beeps—a sign that the collar had either fallen off or that the animal had not moved in days. The mortality signal, as it’s called. Johnson asked the pilot to descend.

“We got a little closer and realized there were little tufts of hair sticking out or a horn sticking out. We were looking at 52 on the ground that had been trapped in the ice,” she said.

The animals had been entombed by what she and her colleagues call an ice tsunami in a new paper, published Thursday in Scientific Reports. During the storm, the musk oxen descended closer to the coast as water receded. But as the frigid tide quickly rose, they were trapped. The water soon rose above the heads of the animals, as wind and surge whipped enormous pans of sea ice ashore. (Later, Johnson would discover chunks of sea ice—five feet wide, eight inches thick—driven more than half a mile inland by the storm.) The musk oxen had no chance.

Pity the musk ox. It is a mysterious, majestic creature, ranging over vast swaths of the far north, from open tundra to pine-laden forest. It survived the last Ice Age, evaded ancient overhunting, and reigns as the Arctic’s largest land mammal. Frankly, it looks like something out of Star Wars.

Yet even the most devoted Arctic biologists know little about them.

“They’re the least-known large North American mammal. They roamed with mammoths. Mammoths didn’t survive, and musk ox did,” says Joel Berger, a professor of conservation biology at Colorado State University and an author of Thursday’s paper.

“There is nothing else left that’s like a musk ox,” agreed Morgan Anderson, an Arctic conservation biologist who did not work on the paper, in an email. “They’re often overlooked ... even in the North, people are usually more concerned with caribou issues.”

It’s a lousy fate. Polar bears are feted by conservation nonprofits and anchor the Greenlandic coat of arms. Arctic foxes are cute and they get a whole international research conference to themselves. Caribou are at the center of the fight over whether to drill in Alaska’s wilderness.

A figure from Thursday’s paper: (A) is a photo taken by Johnson on Valentine’s Day 2011, before the storm surge. (B) and (C) capture the two musk oxen most visible in the aftermath of the “ice tsunami.” (D) shows the nearby tidal gauges from that time. (Berger et al. / Scientific Reports)

Musk oxen, meanwhile, are not only mostly ignored; they’re poorly named, and they only win their superlative on a technicality. Though “oxen” is in their name, musk oxen are more closely related to wild sheep and mountain goats than cattle. As such they prefer the hills to the open plains, and they think nothing of climbing a steep cliff to grab a tuffet of grass. And with adult males weighing in at 800 pounds, musk oxen are only the Arctic’s largest land mammal because the roughly 1,000-pound polar bear is classified as a marine creature.

On top of all this human disrespect, it seems that human industry is already shaping the health of musk oxen at large. In addition to describing the 2011 ice tsunami, the Scientific Reports paper finds that climate change is harming musk oxen babies, impairing their health through their entire early lives.

“If we think about undernourished human babies, we’re seeing the same effects in a land mammal now in the Arctic,” Berger told me.

Over the course of seven years, Berger and his colleagues studied musk oxen herds on both Alaska’s Seward Peninsula and on Wrangel Island, a nature preserve about the size of Yellowstone National Park in the Russian Arctic. In both places, they found that pregnant musk-oxen mothers who faced a specific kind of winter weather—a rain-on-snow event, when liquid rain falls on accumulated snow—gave birth to smaller and less healthy babies. That’s because rain that falls on snow freezes, ultimately coating the snowpack in a top layer of ice. While a musk ox can normally nuzzle snow out of the way, a frozen snowpack effectively closes off all foliage to the musk oxen.

“When rain-on-snow events occur, then basically [a musk-ox mother] doesn’t have access to her salad bowl for a long period of time because it’s frozen,” said Berger. “If you’re an herbivore, and you’re trying to get some salad, and it’s frozen solid, you’re not going to be eating that. And you can’t eat it for weeks or months.”

“When the mother is gestating, if she can’t get food, then it has a long-term effect on the well-being of her growing fetus. Think about an undernourished kid—if you’re born small, then you may be impacted for most of your life.”

Joel Berger

Berger and his colleagues studied this effect without ever touching the animals. Instead, they took photos of musk oxen from about 150 feet away, a technique called “photogrammetry.” By photographing animals from specific angles, they were able to create models of their heads; and by returning every spring, they could monitor the growth of broods over time.

They found that rain-on-snow events during gestation seemed to suppress the head size of musk oxen from birth until the onset of puberty at age four. At that point, other factors begin to override the rain-on-snow signal.

“These kinds of examples of what you could call sublethal effects of climate change—these more subtle effects—are starting to come out now,” said Paul Smith, an Arctic conservation biologist who works for the Canadian federal government and who was not involved in the study.

“There’s this subtle environmental effect that doesn’t kill the individuals, but alters their structural size, and that handicap persists over time,” he said. “The subtle effects are more important in the long term because they affect more of the population. They have been more difficult to describe, but they show just how pervasive the effects of changing climate are.”

In the Canadian Arctic, the number of annual rain-on-snow events has tripled in recent years. Climate change seems to be transforming the entire region. In December, U.S. government scientists warned that the Arctic showed “no sign of returning to [the] reliably frozen region of recent past decades.”

Rain-on-snow events can be one of the most damaging outcomes of that change, at least for wildlife. About 50 caribou in one of Canada’s last Arctic refuges starved to death in 2016 after a rain-on-snow event deprived them of access to food. Some 20,000 musk oxen died after a rain-on-snow event struck a Canadian Arctic island in 2003.

Animals that hide in the snowpack to stay warm—like lemmings or seals—also suffer after these events, as frozen rain makes the snow denser and lowers its temperature. Sometimes their homes can even collapse. “This is suggested as a reason for why the regular up-and-down dynamics of lemming populations are going out of whack,” Smith told me.

Anderson, the Arctic biologist, also praised the use of photography in the study. “The use of photogrammetry to get measurements from free-ranging musk oxen is exciting because it means you can collect data that would otherwise require handling—so you can get more data with less stress on the animals,” she said.

The technique seems to work especially well with musk oxen, because the animals don’t run away from people, but form protective herds. “In times past, we could do cowboy biology, which is with helicopters, dart guns, immobilizations. But the beauty of this approach is that we don’t have to harass the animals that way,” Berger told me.

The trickiest part of the study, said outside researchers, was actually identifying that rain-on-snow events occurred at all. While some scientists now prefer to analyze the density of snowpack through satellite observation, that technique is still new, and the new study used nearby weather-station data instead.

And while the ice tsunami wasn’t as obviously triggered by climate change, it was certainly unusual. Storm surges so early in the year, with so much sea ice already on the Arctic Ocean, are little documented in the literature. And Freddie Goodhope, a local Inupiat leader who works with Berger’s team, said that neither he, nor his parents, nor his grandparents ever remembered or described a frozen surge like the one that occurred in Alaska.

It’s fitting that Berger is studying musk oxen, a creature straight out of the Ice Age, on Wrangel Island. Some of the world’s last mammoths died on Wrangel Island, surviving until just 3,800 years ago. “As we had pyramids being built, we still had mammoths on Wrangel Island,” he said. Next month, he’ll make his regular trip up to that frozen land for his annual research trip. It’s a flight that can only be made the long way—he’ll fly from Denver to New York to Moscow; then to Pevek, Russia’s northernmost city; before helicoptering for another two hours—but it’s also poetic that the Russian government allows him to study there as an American, he said.

That’s because Wrangel Island remains a refuge of sorts—and because Russia’s musk oxen only exist because of international cooperation. Musk oxen had been extinct in Russia for centuries until 1975, when the Soviet Union asked the United States for help resettling musk oxen. The United States happily complied—shipping musk oxen from eastern Alaska to their current home on Wrangel Island.