Sundown on the Arctic

September 22, at 15:30CEST/ 9:30AMEDT marks the autumn equinox, when the sun finally will go down on an Arctic summer like none before.

Multiple heat waves broke records across the region, from Alaska to Greenland to Siberia, where the city of Verkhoyansk reached 100.4°F (38°C), the highest temperature ever recorded within the Arctic Circle.  Svalbard broke its previous record by nearly a degree, at 71°F  (21.7°C).  Nunavut Territory, at 80° latitude in extreme northern Canada, pushed nearly half a degree higher: 71.4°F, the hottest temperature ever recorded that far north on Earth.

Driven by heat, heat-related lightning strikes and humans, fires swept across the Russian Arctic.   2020 broke “annual” records already by the end of August, when carbon emissions from Arctic wildfires reached 244 million tons – about the size of emissions for an entire year from Spain – smashing the previous record (2019) of 182 million tons. Such intense fires trigger permafrost thaw, with carbon emissions that continue for decades or even centuries. And the Arctic wildfire season is far from over: indeed, smouldering peat bogs, so-called “zombie fires” now continue to burn year-round underground, also thawing nearby permafrost, increasing carbon emissions further and providing a ready source of ignition once snow melts in spring.

The Canadian Arctic’s last fully intact ice shelf lost half its size in a single day, July 31, in a dramatic collapse that saw an area larger than Manhattan disappear into the Beaufort Sea.  Part of the Arctic’s largest remaining ice shelf, Spalte Glacier in northeast Greenland, disintegrated completely in late August, losing an area the size of Paris.

Arctic sea ice set a new overall record low for the month of July, and by September 1 stood at the second-lowest extent ever measured.  As of this writing, the low for this summer still had not been reached[i]: Arctic sundown used to mark the beginning of new ice formation, but recent years show continuing decline even after the sun goes down.  In this new, strange Arctic, water simply has remained too warm for much new ice to form until well into October.

Indeed, parts of the Arctic Ocean have now become more similar to the Atlantic and Pacific. Influx of warm nutrients has caused widespread plankton blooms; yet at the same time, the cold waters of the Arctic Ocean absorb CO2 more quickly, making them more acidic and corrosive than waters at warmer latitudes. Ocean acidification is already causing damage to shell-building zooplankton in parts of the Gulf of Alaska, Bering and Beaufort seas, threatening the entire Arctic food chain and rich nearby fisheries.

Throughout the Arctic summer, scientists continued adding to the alarm bells with new research.  Greenland’s loss of ice – a major contributor to sea-level rise along the U.S. Atlantic coast – was not only confirmed as decades-long and accelerating, but locked-in to continue for decades or centuries even should temperatures stabilize.  Ice sheet loss is an ironically classic Titanic scenario: even once danger is known, it is very hard to turn the ship.  Some harm becomes inevitable, and the only way to minimize damage is to start turning as soon as possible.

Zombie fires, collapsing ice, corrosive oceans: if this sounds apocalyptic, it is.  While the world mostly looked away, human carbon emissions – paused only briefly by the Covid-19 crisis – have continued to track worst-case scenarios, despite decades of messages from increasingly alarmed scientists to “turn the ship”.  We’re only beginning to see the consequences of our failure to respond.

Can this extreme Arctic summer convince us finally to reduce emissions, not destructively as when forced by a tragic pandemic, but in ways that support all our societies?  Low-emissions pathways and technologies are well defined: science tells us that we already have all the tools necessary.  We need only pay attention long enough to decide to use them, at a cost far lower than if we wait still another decade or two – until nature forces our hand, just as Covid does today.

Because ultimately, the Arctic does not care about our human timescales, election battles or other reasons to ignore reality.  As it continues warming, it will continue to spin off impacts on all of us: not just sea-level rise, but disturbed weather patterns that may have led to this summer’s terrible fires in California, as the stabilizing impact of the “Earth’s refrigerator” disappears.

Like the inevitable setting sun, our planet’s reaction to our deliberate failure to curb greenhouse gas emissions will continue.  Whether we choose to pay attention, or not.


Dr. Julie Brigham-Grette, University of Massachusetts-Amherst and past Chair (2014-20), U.S. Polar Research Board

Dr. Nina Bednarsek, Southern California Coastal Research Project

Dr. Gustaf Hugelius, Bolin Centre for Climate Research, Stockholm University

Dr. Jessica McCarty, Miami University (Ohio)

Dr. Dirk Notz, University of Hamburg

Pam Pearson, Director, International Cryosphere Climate Initiative

Dr. Heidi Sevestre, University Centre in Svalbard, Norway

Dr. Julienne Stroeve, University of Manitoba and University College London


[i] On September 21, NSIDC preliminarily announced the minimum as 3.74 million km2, reached around September 15, but not yet official.