Climate change, key factor in Antarctic sea ice at record levels: study

Climate change played a key role in last year’s record Antarctic sea ice levels, a study published Monday concluded, marking an abrupt shift from the growth seen in previous decades.

Scientists from the British Antarctic Survey (BAS) have discovered that human-caused global warming has resulted in a once-in-2,000-year decline in ocean surface area across the ice-covered continent.

Compared to an average winter in recent decades, the maximum extent of the Antarctic sea covered by ice has shrunk by two million square kilometers – an area four times the size of France, BAS said.

“That’s why we were so interested in studying what climate models can tell us about how often large, rapid losses like this can happen,” study lead author Rachel Diamond told AFP.

Scientists, after analyzing 18 different climate models, found that climate change quadrupled the likelihood of such large and rapid melt events.

Understanding the cause of sea ice melt is complex, as there are many variables — from ocean water to air temperature to winds — that can affect it, scientists say.

But determining the role of climate change is critical, as ice formation has global impacts, from ocean currents to sea level rise.

Sea ice, which forms from the freezing of salt water already in the ocean, has no noticeable impact on sea level.

But when highly reflective snow and ice give way to dark blue ocean, the same amount of energy from the Sun that was returned to space is absorbed by water, accelerating the pace of global warming.

Recovery unlikely

Unlike the Arctic, where sea ice has been declining since satellite records began in the 1970s, the melting trend in Antarctica is a more recent phenomenon.

Antarctic sea ice increased “slightly and steadily” from 1978 to 2015, according to the BAS.

But 2017 brought a sharp decline, followed by several years of low ice levels.

In the study published in the journal Geophysical Research Letters, BAS researchers also made projections to see if the ice would return.

“It does not fully recover to original levels, even after 20 years,” Diamond told AFP. This means that “average Antarctic sea ice could still remain relatively low for decades to come,” she added.

“The impacts… would be profound, including on local and global climate and the unique ecosystems of the Southern Ocean – including whales and penguins,” said co-author Louise Sime.

Previous BAS studies have shown that abnormal melting has led to the deaths of thousands of emperor penguin chicks.

Raised in the ice sheets, they died when they were plunged into the ocean before they developed their waterproof feathers.

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