because all the snow has melted. What are the
consequences of that?”
Arctic plants survive frigid winters thanks to
that blanket of snow and physiological changes,
known as freeze resistance, that allow plants to
freeze without damage. But once the plants awaken
in response to physical cues of spring — warmer
weather, longer days — and experience bud burst,
they lose that ability to withstand frigid conditions.
That’s fine if spring has truly arrived. But if
it’s just a winter heat wave and the warm air
mass moves on, the plants become vulnerable as
temperatures return to seasonal norms. When
temporary warm air covers thousands of square
kilometers at once, plant damage occurs over large
areas. “These landscapes can look like someone’s
gone through with a flamethrower,” Phoenix says.
“It’s quite depressing. You’re there in the middle
of summer, and everything’s just brown.”
Jarle Bjerke, a vegetation ecologist at the
Norwegian Institute for Nature
Research in Tromsø, saw browning across northern Norway and
Sweden in 2008. The landscape —
covered in mats of crowberry, an
evergreen shrub with bright green
sausagelike needles — was instead
shades of brown, red-brown and
grayish brown. “We saw it everywhere we went, from the mountaintops to the
coastal heaths,” Bjerke says.
Bjerke, Phoenix and other researchers continue
to find brown vegetation in the wake of winter
warming events. Long periods of mild winter
weather have rolled over the Svalbard archipelago,
the cluster of islands in the Arctic Ocean between
Norway and the North Pole, in the last decade. The
snow melted or blew away, exposing the ground-hugging plants. Some became encrusted in ice
following a once-unheard-of midwinter rainfall.
In 2015, the Arctic bell heather, whose small white
flowers brighten Arctic ridges and heaths, were
brown that summer, gray the next and then the
leaves fell off. “It’s not new that plants can die during mild winters,” Bjerke says. “The new thing is
that it is now happening several winters in a row.”
The weather needn’t always be extreme to
harm plants in the Arctic. With warmer winters
and summers, leaf-eating insects have thrived,
defoliating bushes and trees beyond the insects’
usual range. “They’re very visual events,” says
Rachael Treharne, an Arctic ecologist who
completed her Ph. D. at the University of Sheffield
and now works at ClimateCare, a company that
helps organizations reduce their climate impact.
She remembers being in the middle of an autum-
nal moth outbreak in northern Sweden one
summer. “There were caterpillars crawling all
over the plants — and us. We’d wake up with them
in our beds.”
In northernmost Norway, Sweden and Finland
in the mid-2000s, successive bursts of geome-
trid moths defoliated 10,000 square kilometers
of mountain birch forest — an area roughly the
size of Puerto Rico. The outbreak was one of
Europe’s most abrupt and large-scale ecosys-
tem disturbances linked to climate change, says
Jane Jepsen, an Arctic ecologist at the Norwegian
Institute for Nature Research.
“These moth species benefit from a milder
winter, spring and summer climate,” Jepsen
says. Moth eggs usually die at around − 30° C,
While forests that die off can grow back over
several decades, some of these mountain birches
may have been hammered too hard, Jepsen says.
In some places, the forest has given way to heath-land. Ecological transitions like this could be
long-lasting or even permanent, she says.
Once rare, wildfires may be one of the north’s
main causes of browning. As grasses, shrubs and
trees across the region dry up, they are being set
aflame with increasing frequency, with fires cov-
ering larger areas and leaving behind dark scars.
For example, in early 2014 in the Norwegian coastal
municipality of Flatanger, sparks from a power line
ignited the dry tundra heath, destroying more than
100 wooden buildings in several coastal hamlets.
Sparsely populated places, where lightning is
the primary cause of widlfires, are also seeing an
uptick in wildfires. Scientists say lightning strikes
can look like
through with a
The Arctic is warming
more than twice as fast
as the rest of the world.
The higher temperatures
have led to browning in
some areas due to:
which then freeze as
Insects thrive and
move into new areas
to eat plants.
Dry plants plus more
lightning leads to