Antarctic sea ice shrinks to record low – researchers

WASHINGTON: Antarctic sea ice likely shrank to a record low last week, US researchers said Monday, the lowest extent in 45 years of satellite recording.

The National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder said Antarctic sea ice fell to 1.79 million square kilometers (691,000 million square miles) on February 21.

That surpassed the previous record low set in 2022 by 136,000 square kilometers (52,500 sq mi).

NSIDC scientists stressed that the latest figure is preliminary as further late-season melting is still a possibility. They said they would release a final figure on the extent of the ice in early March.

Melting sea ice exposes the thicker ice shelves that support Antarctica’s bedrock ice sheet to waves and warmer temperatures.

Melting sea ice has no discernible effect on sea levels because the ice is already in seawater.

But sea ice surrounds Antarctica’s massive ice shelves, the foothills of freshwater glaciers that threaten catastrophic sea level rise for centuries if they continue to melt as global temperatures rise.

“Antarctica’s response to climate change was different than that of the Arctic,” said Ted Scambos, a senior research scientist at the Cooperative Institute for Research in the Environmental Sciences (CIRES).

“The downward trend in sea ice could be a signal that global warming is finally affecting the floating ice around Antarctica, but it will be several years before that can be relied on,” Scambos said.

The Antarctic cycle experiences significant annual variations during its thawing summers and freezing winters, and the continent has not experienced the rapid melting of the past four decades that has plagued the Greenland and Arctic ice sheets due to global warming.

But the high melt rate since 2016 raises concerns that a significant downtrend could take hold.

Melting sea ice is problematic because it contributes to accelerating global warming.

When white sea ice — which reflects up to 90 percent of the sun’s energy back into space — is replaced by dark, unfrozen sea, the water absorbs a similar percentage of the sun’s heat instead.

Globally, last year was the fifth or sixth warmest on record, despite the cooling influence of a natural weather pattern in La Nina.