Antarctica loses Argentina-size sea ice. It should be back — why isn't it?

This time every year Antarctica's sea ice builds back up. But this year scientists have observed something different.
Sade Agard
Ice and Glaciers and Mountains near the Antarctic circle, Antarctica
Ice and Glaciers and Mountains near the Antarctic circle, Antarctica

Gerald Corsi/iStock 

Antarctica is missing an Argentina-sized amount of sea ice — around 1.6 million square kilometers (0.6 million square miles—reaching unprecedented lows for this time of year, according to a recent CNN article. 

Each year, as the Antarctic summer draws to a close in February, the sea ice surrounding the continent naturally reaches its lowest point, only to grow back during the winter. 

However, researchers have noticed this year that it has not bounced back as usual. 

Antarctic sea ice 2023

Contrary to the Arctic, where sea ice has been consistently decreasing due to the climate crisis, Antarctica's sea ice has displayed significant fluctuations over the last few decades, making it challenging for researchers to discern its response to global heating

However, since 2016, scientists have witnessed a steep downward trend culminating in this winter's alarming record low.

Described as "off-the-charts exceptional" by some scientists, this event is considered so rare that the odds of it happening are estimated to be only once in millions of years. 

Ted Scambos, a glaciologist at the University of Colorado Boulder, emphasized to CNN that the Antarctic system has changed drastically, making previous projections obsolete. 

"The game has changed," he said. "There's no sense talking about the odds of it happening the way the system used to be, it's clearly telling us that the system has changed."

Numerous factors contribute to the sea ice decline, including the strength of westerly winds around Antarctica, which have been linked to increased planet-heating pollution. 

Warmer ocean temperatures north of the Antarctic Ocean boundary also influence the phenomenon, mixing into waters typically isolated from the rest of the world's oceans.

The consequences of diminishing sea ice are significant and far-reaching. Although sea ice doesn't directly contribute to sea level rise as it's already floating, its disappearance has indirect effects.

The coastal ice sheets and glaciers exposed to waves and warm ocean waters become more susceptible to melting and breaking off, exacerbating the global sea level rise.

The impact on wildlife is equally concerning. Species like krill, essential to the region's whales, depend on sea ice for their habitat. Penguins and seals also rely on sea ice for feeding and resting. 

Furthermore, Antarctica's sea ice is vital in regulating the planet's temperature. Its reflective surface bounces incoming solar energy back into space.

Still, as it melts, the darker ocean waters underneath absorb more of the sun's energy, leading to further warming.

Researchers are now racing to understand the underlying causes of this dramatic shift in Antarctic sea ice levels. 

While some caution that it's too early to determine whether this is the new norm, others, like Ted Scambos, fear that this winter's unprecedented event may indicate a long-term transformation of the Antarctic system.