US: The ice shelf was cracking up. Surveys showed warm ocean water eroding its underbelly. Satellite imagery revealed long, parallel fissures in the frozen expanse, like scratches from some clawed monster.
One fracture grew so big, so fast, scientists took to calling it “the dagger”.
“It was hugely surprising to see things changing that fast,” said Erin Pettit.
The Oregon State glaciologist had chosen this spot for her Antarctic field research precisely because of its stability. While other parts of the infamous Thwaites Glacier crumbled, this wedge of floating ice acted as a brace, slowing the melt. It was supposed to be boring, durable, safe.
Planet-warming pollution from burning fossil fuels and other human activities has already raised global temperatures more than 1.1 degrees Celsius. But the effects are particularly profound at the poles, where rising temperatures have seriously undermined regions once locked in ice.
In research presented this week at the world’s biggest earth science conference, Pettit showed that the Thwaites ice shelf could collapse within the next three to five years, unleashing a river of ice that could dramatically raise sea levels.
Aerial surveys document how warmer conditions have allowed beavers to invade the Arctic tundra, flooding the landscape with their dams. Large commercial ships are increasingly infiltrating formerly frozen areas, disturbing wildlife and generating disastrous amounts of trash.
The period between October and December 2020 was the warmest on record. This northern summer saw the second-lowest extent of thick, old sea ice since tracking began in 1985.
Separately, the World Meteorological Organisation confirmed a new temperature record for the Arctic: 37.8C in the Siberian town of Verkhoyansk on June 20, 2020.
This year, three historic melting episodes struck Greenland, causing the island’s massive ice sheet to lose about 35 trillion kilograms. On August 14, for the first time in recorded history, rain fell at the ice sheet summit.
The global loss of ice contributes to dangerously rising oceans. Greenland boasts enough frozen water to boost sea levels 7 metres (though it would take thousands of years to completely melt).