South Pole sea ice is now vanishing at an alarming rate, too

Antarctic sea ice loss has suddenly sped ahead of the long-running decline in the Arctic.

The background: The disappearance of Arctic sea ice has been accelerating since the late 1990s. But it’s been an altogether different story at the South Pole, where ice cover gradually increased in recent decades, confounding scientists.

A dramatic reversal: That story seems to have come to an abrupt end, however, according to a new study. The Antarctic’s sea ice cover reached its peak in 2014 and has since declined by around 2 million square kilometers. It's wiped out about 35 years’ worth of gains in a few years.

What it means: Scientists can’t say with certainty why it took so long for Antarctic sea ice to begin receding, or why the loss accelerated so rapidly. Contributing factors could include ocean heating from the extreme El Niño in late 2015 and early 2016, and a weakened polar vortex changing wind patterns. We also don’t know if current trends are likely to continue. 

Feedback loop: The loss of ice can unleash dangerous feedback effects that threaten to melt sea ice and glaciers at even higher rates.

—James Temple