NYT, Dec. 9, 2020
Shift to a Not-So-Frozen North Is Well Underway, Scientists Warn
By Henry Fountain
The Arctic continued its unwavering shift toward a new climate in 2020,
as the effects of near-record warming surged across the region,
shrinking ice and snow cover and fueling extreme wildfires, scientists
said Tuesday in an annual assessment of the region.
Rick Thoman, a climate specialist at the University of Alaska and one of
the editors of the assessment, said it “describes an Arctic region that
continues along a path that is warmer, less frozen and biologically
changed in ways that were scarcely imaginable even a generation ago.”
“Nearly everything in the Arctic, from ice and snow to human activity,
is changing so quickly that there is no reason to think that in 30 years
much of anything will be as it is today,” he said.
While the whole planet is warming because of emissions of heat-trapping
gases through burning of fossil fuels and other human activity, the
Arctic is heating up more than twice as quickly as other regions. That
warming has cascading effects elsewhere, raising sea levels, influencing
ocean circulation and, scientists increasingly suggest, playing a role
in extreme weather.
This year the minimum extent of sea ice in the Arctic Ocean, reached at
the end of the melt season in September, was the second-lowest in the
satellite record, the scientists reported. On land, the huge Greenland
ice sheet and glaciers in Alaska and elsewhere lost mass at
above-average rates, although the rate in Greenland slowed from last year.
Permafrost, or permanently frozen ground, continued to thaw and erode
along Arctic coastlines, leaving Indigenous communities struggling to
cope with damaged infrastructure.
And perhaps most stunning, snow cover across the Eurasian Arctic reached
a record low in June. The drying of soils and vegetation that followed
contributed to wildfires that burned millions of acres of taiga, or
boreal forest, particularly across Siberia. The fires spewed a third
more heat-trapping carbon dioxide into the atmosphere than the year
before, according to European researchers.
The amount of snow that fell across the Eurasian Arctic was actually
above normal this year, said Lawrence Mudryk, a researcher with
Environment and Climate Change Canada and lead author of the section on
snow cover in the assessment. “Despite that, it was still warm enough
that it melted faster and earlier than usual,” he said.
The warmth was pervasive across the Arctic. The average land temperature
north of 60 degrees latitude, as measured from October 2019 through
September, was 1.9 degrees Celsius, or 3.4 degrees Fahrenheit, above the
baseline average for 1981-2010 and the second-highest in more than a
century of record-keeping.
The outsized influence of the Arctic is why the assessment, called the
Arctic Report Card, has been produced annually for the past 15 years by
the National Oceanic and Atmospheric Administration. More than 130
experts from 15 countries contributed to this year’s version, which was
issued at the annual conference of the American Geophysical Union.
In recent years Arctic researchers have increasingly come to recognize
that the region is moving from a climate that is characterized less by
ice and snow and more by open water and rain.
In a study published in September, two researchers with the National
Center for Atmospheric Research, in Boulder, Colo., argued that for sea
ice at least, a permanent shift had already occurred. Ice extent has now
declined so much, Laura Landrum and Marika M. Holland wrote, that even
an extremely cold year would not result in as much ice as was typical
decades ago.
Donald K. Perovich, a professor at Dartmouth College and the lead author
of the chapter on sea ice in the assessment, said that 2007 was a
critical year. “We had the largest drop in ice extent we’d ever seen,”
he said. “While there have been these variations since, we’ve never
returned to those levels before 2007.”
“It’s as though we’re in this new state,” he said.
The age of sea ice is declining as well as the region warms. Three
decades ago, ice that was at least four years old made up about a third
of the Arctic Ocean pack ice at the end of winter. This year, according
to the assessment, old ice accounted for less than 5 percent of the pack
ice.
The increasing dominance of younger, and thus generally thinner, ice has
contributed to the reduction in sea-ice extent, Dr. Perovich said, since
thinner ice is less likely to last through a single season.
The shift from old to young ice has also led to a decline in overall ice
volume. Volume this year, measured at the end of the melt season in
September, was the second-lowest in the 10 years that satellites have
been making reliable measurements.
The assessment noted how conditions in the Arctic affected the Mosaic
expedition, in which a German research icebreaker was deliberately
allowed to freeze into the pack ice north of Russia and drifted across
the Central Arctic for most of a year. The expedition, Mosaic, 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 struggled
to find an ice floe to use as a mooring that was thick and stable enough
to last through months of drifting. And as the voyage proceeded, the
wind patterns that brought such warm temperatures to the Arctic also
caused the ice and the ship to drift much faster than expected.
Henry Fountain specializes in the science of climate change and its
impacts. He has been writing about science for The Times for more than
20 years and has traveled to the Arctic and Antarctica. @henryfountain •
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