The Arctic continued its unwavering shift towards a new climate in 2020 as the effects of near-record warming increased in the region, ice and snow cover shrank and extreme forest fires, scientists said in an annual assessment of the region on Tuesday.
Rick Thoman, Climate Specialist at the University of Alaska and a co-editor of the review, said, “It describes an arctic region that continues on a path that is warmer, less frozen and biologically altered in a way that even a generation could hardly imagine in front.”
“Almost everything in the Arctic, from ice and snow to human activity, changes so quickly that there is no reason to believe that much will be what it is today in 30 years,” he said.
While the entire planet is warming due to the emission of gases that trap heat from burning fossil fuels and other human activities, the Arctic is warming more than twice as fast as other regions. This warming is cascading effects elsewhere, raising sea levels, affecting ocean circulation, and, according to scientists, increasingly plays a role in extreme weather conditions.
That year, the minimum level of sea ice in the Arctic Ocean reached at the end of the melting season in September was the second lowest on the satellite record, the scientists reported. On land, the vast Greenland ice sheet and glaciers in Alaska and elsewhere lost more than average mass, although the rate in Greenland slowed compared to the previous year.
Permafrost, or permanently frozen ground, continued to thaw and erode along the Arctic coast, leaving indigenous communities struggling to cope with damaged infrastructure.
And what is perhaps the most breathtaking snowpack in the Eurasian Arctic hit a record low in June. The subsequent drying up of soils and vegetation contributed to forest fires that burned millions of acres of taiga or boreal forest, particularly across Siberia. According to European researchers, the fires spewed a third more carbon dioxide into the atmosphere than in the previous year.
The amount of snow that fell over the Eurasian Arctic this year was actually above normal, said Lawrence Mudryk, researcher at Environment and Climate Change Canada and lead author of the section on snow cover in the assessment. “Even so, it was still warm enough that it melted faster and earlier than usual,” he said.
The warmth was ubiquitous throughout the Arctic. The average land temperature north of 60 degrees latitude, measured from October 2019 to September, was 1.9 degrees Celsius or 3.4 degrees Fahrenheit, above the base average for 1981-2010, and was the second highest in more than a century of record.
The oversized influence of the Arctic is why the assessment, known as the Arctic Report Card, has been produced annually by the National Oceanic and Atmospheric Administration for the past 15 years. More than 130 experts from 15 countries contributed to this year’s version, which was released at the annual conference of the American Geophysical Union.
In recent years, Arctic researchers have increasingly realized that the region is moving away from a climate that is less characterized by ice and snow than by open water and rain.
In a study published in September, two researchers from the National Center for Atmospheric Research in Boulder, Colorado argued that a permanent shift had already occurred for at least sea ice. The extent of the ice has now decreased so much, wrote Laura Landrum and Marika M. Holland, that even an extremely cold year would not produce as much ice as was common decades ago.
Donald K. Perovich, professor at Dartmouth College and lead author of the chapter on sea ice in the assessment, said 2007 was a critical year. “We’ve had the biggest drop in ice we’ve ever seen,” he said. “While these variations have been around since then, we never returned to these levels until 2007.”
“It’s like we’re in this new state,” he said.
The age of the sea ice is decreasing and the region is warming. Three decades ago, ice that was at least four years old made up about a third of the Arctic Ocean’s pack ice by the end of winter. This year, old ice was estimated to make up less than 5 percent of the pack ice.
The increasing dominance of younger, and therefore generally thinner, ice has contributed to reducing sea ice extent, said Dr. Perovich, as thinner ice is less likely to last a single season.
The shift from old to young ice has also resulted in a decrease in total ice volume. This year’s volume, measured at the end of the melting season in September, was the second lowest in the 10 years that satellites have taken reliable measurements.
The assessment determined how conditions in the Arctic affected the mosaic expedition, in which a German research icebreaker was deliberately allowed to freeze into the Russian pack ice and drifted across the central Arctic for almost a year. The Mosaic expedition ended in October when the ship left the pack ice between Greenland and Norway and returned to Germany.
At the beginning of the expedition in September 2019, the ship tried to find an ice floe that would serve as a mooring and be thick and sturdy enough to withstand months of drifting. And as the voyage continued, the wind patterns that brought the Arctic to such warm temperatures also made the ice and ship drift much faster than expected.