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Midwinter ice storms deadly for Alaska's animal herds

Craig Medred

0131-ice-caribouOnce more ice coats the brush and snow of Northwest Alaska, and Alaska Department of Fish and Game biologist Jim Dau wonders how the caribou will fare this time. Twice since 2005, the animals of the Western Arctic caribou herd have been hit hard by ice storms that threatened to lock their forage away beneath a layer of white pavement. After the first of those storms, large numbers of caribou suffered from starvation. Dau described them as dying "in droves."

They have not been the only animals to struggle with winter ice in Alaska's volatile climate in recent years, either. In the Chugach and Kenai mountains, Tom Lohuis, a Fish and Game biologist studying Dall sheep, has begun to examine icing as a possible cause of significant mortality. Lohuis is early in his studies but he has already found evidence in the Dall sheep population of Southcentral that is analogous to what Dau has seen in the Arctic -- animals hard pressed to survive because of a layer of ice coating the ground or the snow. Neither caribou nor sheep are well equipped for chipping through frozen surfaces to get at their food. Both Dau and Lohuis have seen ice related deaths and use the phrase "bags of bones" to describe the animals that manage to survive winters with serious ice events.

The big question now focuses on whether these ice events are a new phenomenon or an old one that has newly attracted attention. The question is simple: Is this icing related to a shift in climate or have all the discussions about "global warming" over the last decade merely caused scientists to finally notice long-existing, climate-related phenomenon, some of which have been obvious to generations of Alaskans that work the land?

Problems caused to polar bears by a demonstrably shrinking polar ice cap are hard to miss. Bears that die of exhaustion or lose their cubs on increasingly long swims between dens on the Alaska coast and the ice where they hunt seals are visible victims of global warming just as some other species are visible beneficiaries.

Likewise, the northern and westward expansions of moose and beaver in Alaska have been linked to forests migrating farther north and west since a general climatic warming began near the end of the 19th century. Booming Alaska salmon populations have been similarly linked, in part, to warming in the North Pacific Ocean and the Bering Sea. Outside the scientific community, of course, these latter events have been little noticed as climate-related because they are collectively considered as "good."

If global warming means more salmon, who in Alaska could oppose it? On the other hand, if it means extinction of the polar bear or shrinking Alaska caribou herds, who wouldn't oppose it?

And if it does both of these things, what then?

Global warming is a difficult topic to address in Alaska because it isn't just about warming. It's about climate change -- if not microclimate change.

Nature's law: Some Arctic animals win, others lose

Dau lives in Kotzebue, just north of the Arctic Circle. Reindeer herder Jimmy Noyakuk lives in Teller on the Seward Peninsula, just south of the circle. Noyakuk's reindeer and the caribou Dau studies are first cousins. The two men share concerns about the environment, and both agree that when it comes to climate change there is a fine, fine line between the good and the bad.

"We had a good thaw here," Noyakuk told Alaska Dispatch during a telephone interview from Teller the last week of January. But Noyakuk said the thaw didn't appear to result in much ice. Instead of locking away forage for his reindeer, it appeared to expose more of it. The weather went cold after the thaw, but the snow that came with it was equally cold. It was light and easy for the reindeer to brush aside with a foot to get at food.

"Caribou are very well adapted to survive in snow and cold," Dau said. So too reindeer. Though the temperature was back to 20 degrees below zero on the Seward Peninsula this week and there was snow on the ground. But Noyakuk's reindeer were doing fine.


The situation he describes on the peninsula now sounds similar to what Dau saw to the north, near the Brooks Range mountains in January 2007, when it rained for four days. That is a most unusual occurrence. The biologist expected the bizarre weather to again kill a bunch of caribou as it had in 2005. Only it didn't. The rain washed away the snows. High winds caused the rain to evaporate instead of freezing on the tundra. No ice crust formed. And the caribou, rather than being cut off from their food, had access to more. Dau describes the weather as "playing Russian roulette" with the caribou. Some believe this threatens caribou over the long term.

"Caribou are better adapted to cold than to warmer, moister weather," Canadian author Ed Struzki observed in the September issue of "Yale Environment 360." Struzik has implicated icing in the decline of the Peary caribou herd from about 24,000 animals in 1961 to about 2,000 today. The Peary caribou range across Canada's Arctic Islands in the Northwest Passage west of Greenland.

"At least two catastrophic freeze-ups that were caused by early fall ice storms and rains and early, short-lived spring thaws resulted in more than 90 percent of the animals starving to death because they could not punch through the ice to get to food," he wrote. "Scientists in the far-northern Norwegian archipelago of Svalbard told me earlier this spring that they are seeing the same kind of icing take a toll on reindeer in that region."

Scientists studying Alaska reindeer reported much the same in the journal of "Polar Research," noting "rain and thaw-freeze events in midwinter hinder travel and create an icy surface making it difficult for reindeer to dig for forage."

This could pose a problem if icing events become the norm; but then again, maybe they've been the norm. Noyakuk started herding reindeer in 1971 when he was 16 years old. He's seen plenty of odd winters since, and he's not sure there is a pattern.

"We get one of these warms years every once in a while," he said.

Predicting future climate is even more difficult than predicting tomorrow's weather, and anyone who pays attention to the latter knows how often professional weathermen get the forecast wrong. Even today's most sophisticated meteorological tools cannot always predict weather.

Climatologists face an even more difficult task. The global climate is a big, swirling mass of air that surrounds the planet, and scientists don't really know a fraction as much about it as they would like to know. As earth rockets through space, it spins around its northern and southern poles, and that spinning creates high-altitude winds that flow, swirl and eddy much like the currents in a river. Climate experiences the same sort of turbulence, if not more. That makes it hard for climatologists to predict what will happen in the state as a whole in the future, let alone what might happen on the smaller plots of land home to herds of caribou or sheep.

John Walsh, the director of the Center for Global Change and Arctic Research at the University of Alaska Fairbanks, confessed to the big gaps in knowledge in a 2005 interview with a journalist for the Fairbanks institution. What scientists could say, he said, was Arctic Alaska "cooled from about 1940 to 1970, and then it warmed from 1970 to 2000 at a good rate. Now, we don't know if the present warming is going to continue for another 10 or 20 years, and then there will be another downtick. We don't know if a downtick will set in fairly soon. It could go either way."

And as is always the case in nature, some animals will lose out while others benefit. Societal perceptions, meanwhile, will be shaped by the perceptions of humans and their value judgments. Few are likely to complain if climate change leads to the deaths of massive numbers of rats, or reduces Alaska's mosquito population, but if the victims are polar bears or caribou or Dall sheep?

Contact Craig Medred at craig(at)alaskadispatch.com