In the winter of 2012, the Svalbard archipelago was hit with an extreme weather event of record-breaking heat and rain—a slush avalanche knocked out bridges and roads. Reindeer carcasses littered the landscape, as permafrost warmed and snow-dependent tourism took a major hit.

Now, a group of scientists documenting the aftermath of the two-week event says that Svalbard's experience offers a preview of sorts of what other Arctic regions may experience with ongoing warming. The region has experienced the highest temperature increase in Europe the last three decades, according to researchers.

"Svalbard is regarded as a climate change bellwether for many other Arctic areas, since the warming has already happened very rapidly. Winter temperatures have risen on average more than 4 degrees since the 1990s," said Brage Bremset Hansen, a researcher at Norwegian University of Science and Technology and author of the study in Environmental Research Letters.

The archipelago—which sits between Norway and the North Pole—also offered a rare opportunity to study such an extreme event, as it held a unique amount of research infrastructure and a network of weather stations to collect data in comparison to other Arctic areas, he said.

The archipelago also contains a mixed population of animals and people. About 2,000 people live in Longyearbyen, the archipelago's largest town, while other towns have as few as two dozen residents in winter. In the animal population, there are four main vertebrate species in winter—including Arctic foxes, sibling voles and wild reindeer, which are eaten by humans.

In January 2012, a high-pressure system over northern Scandinavia sent mild and humid air northward to Svalbard.

The result was a series of record or near-record events during polar nights. Temperatures rose as high as 7 degrees Celsius, when the average temperature is approximately minus 14. In Ny-Ålesund, 98 millimeters of rain fell in one day at the end of January, something that typically happens once a century. Seventy percent of the annual average of rain fell in two weeks.

Ironically, the warmth and precipitation generated a thick coat of ice on the ground, as heavy rain percolated through snowpack and froze. "The ice layer covered most of the tundra and was extremely slippery," said Hansen.

Landslides and a slump in tourism
That, in turn, made migration and feeding difficult for local reindeer during a critical time of year, as their vegetation food source became encapsulated in ice. The following summer, reindeer carcasses dotted the landscape at levels far above average.

A slippery runway, meanwhile, closed down the Svalbard airport for two days. Snowmobile riding, dogsledding and other tourism activities became impossible on the icy surface, depriving the region of a chief source of income. In general, tourism activities dropped by roughly 28 percent in comparison to the previous winter, according to the study.

Perhaps most worrisome for locals, the area was hit by several avalanches, as snowpack on mountains surrounding towns became slushy and saturated from heavy rain. In the middle of Longyearbyen, a pedestrian bridge was wiped out, along with many roads.

Residents "were of course especially concerned about the one avalanche that took out the pedestrians' bridge close to the elementary school," said Hansen, who traveled to Svalbard after the weather event.

The buildings issue is a particular concern for the future, said Hansen, as most of the infrastructure in Svalbard is not designed for disasters.

Much "is located in areas exposed to slush or debris flows," the paper states.

An anomaly, or the future?
Additionally, permafrost temperatures rose at least 5 meters in depth. While there was not unusual thaw in 2012, additional rise in permafrost temperatures could destabilize soils and mountainsides, with implications for roads, buildings and other infrastructure, said Ketil Isaksen of the Norwegian Meteorological Institute, a co-author of the paper.

While there are uncertainties about precipitation patterns, models suggest the area will continue to warm, Isaksen said. According to one model run for the paper, midwinter mean temperatures could rise above zero Celsius by midcentury under a moderate emissions scenario.

The warming in Svalbard is typical of the rest of the Arctic, but there is a wild card in terms of the future frequency of freezing rain events, said John Walsh, a chief scientist at the University of Alaska, Fairbanks, who called the work "an interesting case study." Atmospheric circulation was unusual in 2012, as persistent winds from the south and southeast brought warmth to Svalbard during the winter in question, said Walsh, who did not participate in the research.

"With regard to the future, the big unanswered question is: Will that type of circulation pattern become more common in coming decades?" he said.

Similarly, U.S. National Oceanic and Atmospheric Administration oceanographer James Overland said future warmer overall temperatures may produce warmer extreme events, but Svalbard in particular is difficult to analyze in terms of a link with climate change. It "is at the end of the North Atlantic jet stream and is noted for its wide year-to-year variation in monthly temperatures and weather," he said, noting that there were a string of very warm monthly events in the 1920s.

Hansen is doing additional work on plants in the area, as most are less than a few inches tall and are vulnerable to multiple months covered in ice. "We don't know how they handle this," he said. In the long run, he said, he is hoping to raise funding to look at the "broader ecosystem," including impacts on summer migratory species.

Not all the news from the event was negative, he said. Despite the reindeer deaths in 2012, the population of the animals has often done well because of increases in summer temperatures helping food supply during that season. The animals had a decent winter directly before the event, so the extreme event could have been much worse, he said.

"I don't think this event was a food security issue," he said.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500