Antarctica is missing sea ice the size of Argentina and scientists cannot explain why

Antarctica is missing sea ice the size of Argentina and scientists cannot explain why.

Deadly heatwaves, raging wildfires, and record global temperatures are upon us. But far from the flames, at the southernmost tip of the planet, something just as shocking is unfolding.

It’s Antarctic winter, a time when the area of floating sea ice around the continent should be rapidly expanding. This year though, the freeze-up has been happening in slow motion.

Each year, the amount of sea ice around Antarctica fluctuates enormously. In the Antarctic summer, starting in December, the sea ice melts rapidly. Some seas around Antarctica are virtually ice-free by March. Then, as Antarctic winter approaches, the ice begins to grow again. At its most expansive, the sea ice covers an area the size of Antarctica itself – essentially, the frozen continent doubles in size.

But the amount of sea ice has been slowly decreasing in recent years. And, this year, the ice is significantly smaller than it ever has been. As of late June, almost a million square miles of ice was missing from the ocean around Antarctica. It’s the smallest amount of ice ever measured around the continent since 1979, when satellites allowed scientists to track such events annually.

In the face of more immediate climate concerns, why does Antarctic sea ice matter?

Floating sea ice is a pivotal climate puzzle piece. Without it, global temperatures would be warmer because its bright, white surface acts like a mirror, reflecting the sun’s energy back to space. This keeps the Antarctic – and by extension, the planet – cool.

Less sea ice means more sea level rise

The missing ice is a problem for people far from Antarctica. While sea ice loss doesn’t contribute directly to sea level rise – melting sea ice doesn’t add any extra water to the ocean – Antarctic sea ice acts like a protective collar around the continent. The sea ice shields Antarctica’s glaciers and massive ice shelves from ocean waves and above-freezing ocean water that hasten melting.

“Those ice shelves contain a lot of frozen water, and if they break and become a part of the ocean, that’s going to raise global sea levels,” says Marilyn Raphael, who studies Antarctic sea ice at the University of California, Los Angeles.