‘Nearly 75 times Belgium’s surface is missing’: Scientists worry about historic decline of sea ice around Antarctica |  Science and the planet

‘Nearly 75 times Belgium’s surface is missing’: Scientists worry about historic decline of sea ice around Antarctica | Science and the planet

There was very little sea ice around Antarctica. In February, a historic low was reached. At that time there was only 1.79 million square kilometers of sea ice. And even now, in the middle of winter, ice extent remains at record low levels. We currently have a deficit of 1.15 million square kilometers. Not in relation to what is normal, but in relation to the previous record. Although it is still difficult for scientists to distinguish between anomalies in Antarctica’s climate and the contribution of climate change, says climatologist Lander van Trecht (VUB).

what is going on?

Maps showing sea ice anomalies in Antarctica are colored red. Like sea ice near the North Pole, sea ice in Antarctica is subject to seasonal growth and decline. But this year’s winter growth is happening much slower after the historically low summer minimum in February.

Read more below the image.

Sea ice anomaly Antactica © Nilas – Southern Ocean Mapping Platform


“As of mid-June 2023, the extent of Antarctic sea ice was about 2.28 million square kilometers less than the 1981 to 2010 average for that time of year, and about 1.15 million square kilometers less than the previous record set in June 2019 both roughly matching a shortfall,” says Fan. Tricht: 75 and 37 times the size of Belgium.So the current volume remains exceptionally low for that time of year.

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look. Researchers share photos of an iceberg that broke off in January in Antarctica

Has this always been the case?

In contrast to the declining sea ice trends in the Arctic and Greenland, sea ice around Antarctica has been gradually increasing since the 1970s. However, this trend abruptly changed in 2016 when sea ice suddenly began to recede.

Van Trecht: “The question is whether this trend will continue in Antarctica or whether it will return to the small increases that have been observed since the 1970s. In fact, unlike most climate effects that get progressively worse over longer periods, the change has occurred in ice Maritime Antarctica suddenly.”

Read more below the image.

After a steady increase in sea ice since 1970, the trend has reversed since 2016
After a steady increase in sea ice since 1970, the trend has reversed since 2016 © Will Hobbs

Do scientists know the reason for this sudden change?

The expected trend, based on climate predictions, was that sea ice around Antarctica would gradually decrease. However, it is unclear why the current developments occurred.

“Discerning the contribution of climate change from internal anomalies within the Antarctic climate system is challenging for scientists,” Van Tricht explains. Several factors, such as warming oceans, warmer winds, and feedback mechanisms contribute to this decline. An example of this is the albedo effect, whereby darker seawater can absorb more solar heat due to the shrinking surface of sea ice. But in addition to the effects of climate change, internal variations within the system, such as El Niño and La Niña, also play a role.” At the moment, the exact cause of the decline since 2016 remains unknown.

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Are there consequences for sea level?

Melting sea ice does not contribute to sea level rise. But sea ice around Antarctica has a protective effect on glaciers in Antarctica. “Without sea ice protection, glaciers in Antarctica are directly exposed to warming ocean waters and tend to accelerate,” Van Trecht explains. An example is the Thwaites Glacier. If the Thwaite glacier melts, it could lead to a significant rise in global sea levels.”

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