The midnight sun shines across sea ice along the Northwest Passage in the Canadian Arctic Archipelago on July 23, 2017. The passage was open this summer due to low ice concentration – a boon for shipping traffic, but disturbing to the Arctic ecosystem. David Goldman/Associated Press file

The bison couldn’t crack the ice. As Christmastime wound down last year, unseasonably warm temperatures and heavy rain in Alaska’s Delta Junction melted snow and ice, which quickly refroze due to subzero temperatures near the surface. Usually, the bovine can shovel through snow with their heads and horns, but the frozen snow and ice persisted like a layer of cement atop the grasses and plants they need to feed on. And the bison couldn’t get through.

About 180 bison, or a third of the Delta herd, starved to death. Those that survived were skinny and in poor form. Bison season in the Delta Junction area, one of the most popular hunting seasons in Alaska, was cut short from six months to two weeks.

It was one of several exceptional events the Arctic experienced over the past year, all intensified by a warmer world. A typhoon, formed in unusually warm waters in the North Pacific, hit the western coast of Alaska as the state’s strongest storm in decades. A late heat wave in Greenland caused unprecedented melt in September, which can contribute to sea level rise. Despite decent winter snow in Alaska, the rapid onset of summer created devastating conditions for wildfires that burned a record million acres by June.

The recent events are a continuation of a decades-long destabilization in the Arctic region, researchers said in the 2022 Arctic Report Card, a new federal assessment of the region released Tuesday. Since the first report card was issued in 2006, researchers have documented a decline in the polar environment, with loss from sea ice to wildlife. As time goes on, many of the effects of a warmer, wetter and stormier Arctic are coming into a clearer focus.

“As we see changes in the Arctic, its connectivity to the rest of the world only increases,” said Matthew Druckenmiller, the lead editor of this year’s assessment and a research scientist with the National Snow and Ice Data Center. “We will continue to see dramatic changes that will not only transform ecosystems but that will more and more highlight the winners and losers. And I think our context will be a lot more losers than winners.”

Here are key findings from this year’s 133-page report, including additions on rainfall trends and observations by Arctic indigenous people.

RECORD WARMTH IS INCREASING RAINFALL

Arctic annual surface-air temperatures from October 2021 to September 2022 were the sixth warmest on record. The ranking continues a disturbing trend: The past seven years in the Arctic have been the hottest seven years since 1900.

The warmer temperatures are causing major shifts in ecological and landscaping processes in the Arctic. Summer is coming earlier and winter is starting later, the report found, decreasing the length of the snow season.

For example, snow cover in June across the region has declined around 20 percent in recent decades. Even though winter snow accumulation was above average this year, warmer temperatures are causing it to melt earlier. The report, which used a reference period from 1991 to 2020, found overall snow cover was below average, which tracks with trends observed over the past 15 years.

The earlier snowmelt and the hot, dry conditions in Alaska were a critical factor in the widespread wildfires this summer. More than 2 million acres burned across the entire state by July. Wildfire smoke worsened air quality, reducing visibility at the Fairbanks airport.

Warmer temperatures are also increasing the amount of rain across the Arctic. In a hotter world, heavy precipitation events are becoming 7 percent more intense for every 1.8 degrees Fahrenheit of warming. The Arctic experienced wetter-than-normal conditions for the much of the past year, part of a longer trend. According to the report, Arctic precipitation has significantly increased since the 1950s across all seasons and data sets.

Druckenmiller said the sudden, extreme rain last December that led to the starvation of the numerous bison was a “really terrible example” of how the increased rainfall can affect communities.

“We are seeing increased precipitation across the Arctic within all seasons … That not only means total accumulation, but it also means longer periods of wet conditions,” Druckenmiller said.

He added that the rain “can have implications for local communities in terms of being able to manage local waterways and they might see increased rates of flooding.”

LOW SEA ICE AFFECTING HUMAN ACTIVITY

Warm Arctic temperatures are continuing to decrease the thickness and area of sea ice. In 2022, similar to the year before, the sea levels were much lower than the long-term average.

The decades-long loss of ice has boosted ship traffic in the region – less ice blocking travel paths means more available routes for vessels. This summer, the Northern Sea Route and Northwest Passage were able to be open due to the low ice concentrations, making travel easier for tourists and research vessels. The authors of the assessment found ship traffic has been increasing from 2009 to 2018, most significantly from ships traveling from the Pacific Ocean through the Bering Strait and Beaufort. However, they caution the increased ship traffic can disturb the Arctic ecosystem.

In a new feature, this year’s report included observations from indigenous Alaskan communities that describe changes to hunting practices in recent decades. Inupiaq and Inuit people share on-the-ground observations from their cultures’ centuries of life experience and knowledge of the land.

“When you have an oral history that is still living 500 generations later, there are things that science and scientists, which is under 200 years old, could learn from,” said Jackie Qatalina Schaeffer, a co-author of the report and an Inupiaq from Kotzebue, Alaska.

The sea ice retreat forced hunters to travel as far as 100 miles from their homes to find walruses during the spring harvest. The thinning of sea ice has also made seal hunting dangerous in some communities.

Indigenous hunters have doubled the number of days spent hunting bowhead whales in open water in Utqiaġvik, Nuiqsut and Kaktovik but face higher waves with less sea ice. The heightened waves pose a larger risk to hunters and are pushing some villages to buy larger and stronger boats, which have become more expensive to fuel, in part due to the war in Ukraine. The bowhead whales are now migrating earlier in spring and later in the fall, shifting the hunting season for some crews as well.

“We’re not a reactive culture,” said Qatalina Schaeffer, who is also director of climate initiatives for the Alaska Native Tribal Health Consortium. “We plan and we adapt and then we sustain. And that’s how we survive.”