南極なんきょくヘクトリア氷河ひょうが、史上しじょう最速さいそくの縮小しゅくしょう――地球ちきゅう規模きぼの海面かいめん上昇じょうしょうリスクを警告けいこく

According to the latest research, the Hektoria Glacier in Antarctica has shrunk to about half its original size in just two months, an extremely short period of time.

This phenomenon is an example of glaciers retreating at an unprecedented rate in modern history, and it has been pointed out that it could have a serious impact on global sea levels in the future.

Hektoria Glacier has an area almost the same as the city of Philadelphia, Pennsylvania, and is located at the tip of the Antarctic Peninsula.

The Antarctic Peninsula is a mountain range extending from the Antarctic continent toward South America, and is considered one of the most rapidly warming regions on Earth.

Normally, glaciers in contact with the seafloor retreat only a few hundred meters per year, but the Hektoria Glacier experienced a rapid retreat of about 8 kilometers in just a short period from November to December 2022.

This was confirmed by research results published in the journal Nature Geoscience.

Researchers warn that if larger glaciers retreat at the same rate, it could have a devastating impact on global sea levels.

There is so much ice in Antarctica that, if it were to melt, it could raise the global sea level by about 58 meters, so any changes here could have unpredictable effects on the Earths environment.

The research team at the University of Colorado Boulder conducted a detailed analysis of the fluctuations of the Hector Glacier using satellite images and aerial data.

The results indicate that the rapid retreat of glaciers progresses through multiple stages.

In 2011, the bays around the glacier were covered with fast ice, and the glacier itself was relatively stable.

However, in 2022, the established ice separated from the bay, causing the glacier to become unstable and resulting in the disappearance of part of the ice tongue.

Furthermore, from 2022 to 2023, the collapse of the fixed ice shelf allowed seawater to penetrate into the glacier, accelerating its rate of shrinkage.

One of the reasons why the Hector Glacier is collapsing much faster than the surrounding glaciers is that it is moving as if sliding over a flat layer of sediment on the seafloor.

When glaciers become thinner, they rise up, allowing seawater to flow into the crevasses below, increasing the pressure. This causes massive chunks of ice to continuously break off a process called calving, leading to rapid retreat.

Such melting of ice masses was also observed at the end of the last ice age, about 15,000 to 19,000 years ago, but researchers say that there has never been a case where it proceeded at the current speed.

Furthermore, the retreat of the Hektoria Glacier is believed to be closely related to climate change.

The disappearance of sea ice from the ocean areas surrounding glaciers is related to rising seawater temperatures, and as large waves break up the fast ice, glaciers become directly affected by seawater.

According to Ted Scambos, a senior researcher at the Earth Science Observation Center at the University of Colorado, the Hektoria Glacier itself is relatively small by Antarctic standards, so the disappearance of a part of it would not immediately cause a rise in global sea levels. However, he emphasized that he cannot rule out the possibility that larger glaciers could rapidly retreat due to the same mechanism.

Without a doubt, the movement of Antarctic glaciers is a crucial factor that will determine the future of the Earths environment.