Spectacular green iceberg: Chinese icebreaker enters key Antarctic area for climate study

Chinese icebreaker Xuelong-2 has reached Antarctica's Amundsen Sea, a key area for studies on controlling sea-level rise, witnessing a breathtaking spectacle in the heart of Antarctica: a colossal iceberg shimmering with an otherworldly emerald glow.

China is carrying out its second comprehensive study in the Amundsen Sea during the country's 40th Antarctic scientific expedition, and its icebreaker Xuelong-2, or Snow Dragon-2, entered a dense floating ice area around the Amundsen Sea on Thursday morning.

The crew adjusted the travel route based on real-time data from sea ice-detecting radar and satellite remote sensing images. This dramatic encounter marks a new chapter in the country's polar exploration and scientific research.

Xiao Jinfeng, the captain of Xuelong-2, told China Media Group (CMG): "We have entered the dense floating ice area, and we'll keep a safe speed to avoid hitting a large (piece of) ice or iceberg. And if we encounter large pieces of thick ice, our ship is able to break ice with a thickness of 1.5 meters plus 0.2 meters of snow covering the ice."

Special colors and shapes of sea ice

The sea ice and icebergs in Antarctica are normally white, and those with special colors have drawn attention from scientists.

Talking about the picture of a green iceberg, Professor Shi Jiuxin, Ocean University of China, told CMG that the green iceberg was formed by pieces of glacier ice containing iron oxide from the Antarctic ice sheet that had fallen into sea.

"This iceberg shows the color of green. Actually this part we see here is what has been flipped over as it was originally hidden under the sea surface. It looks green now because it contains some of iron." 

Some sea ice in the Antarctica even show colors of yellow and brown. "After the Xuelong vessel breaks ice and turns it upside down, we could directly see its yellow bottom, like this, which is actually the color of algae, we call it ice algae, the main source of diet for krills," Shi added.

Moreover, even in winter, some areas of sea surface in the Antarctica remain unfrozen, forming what scientists call polynyas. "When the wind is strong, the sea ice breaks up. They bump into each other and the edges thicken and form this ice. In China, it is generally called lotus ice, which looks very much like lotus leaves, and people in the foreign country call it pancake ice which looks like pizza. It is thick on the edges and thin in the middle," Shi added.

Record shrinking of sea ice

Multiple factors, mostly related to human activities, contributed to a drastic drop in scale of Antarctic sea ice in 2023, experts say.

Studying Antarctic sea ice is very important to addressing the global climate change. The latest research suggests that Antarctic sea ice area hit a record low in 2023.

Liu Tingting, professor from the Chinese Antarctic Center of Surveying and Mapping of Wuhan University, told CMG that "the extent of Antarctic sea ice has reached a new historical low in the southern hemisphere summer in 2023."

"This is an issue of great concern to everyone. So far, I have roughly estimated that the scale of sea ice in Antarctica this summer has decreased by over 10 percent (compared to the level in 2015-2016)," Liu added.  

Data released by the U.S. National Snow and Ice Data Center shows that the Antarctic sea ice scale is at its lowest level since records began 45 years ago. In mid-July 2023, which is the winter in the southern hemisphere, the Antarctic sea ice area decreased by 2.6 million square kilometers compared with the 1981-2010 average. This number is almost the same as the land area of Argentina.

A research report released by the European Space Agency shows that in the past 25 years, the mass of 48 Antarctic ice shelves has decreased by more than 30 percent compared with its original mass.

"One of the main influencing factors is anomalies in atmospheric circulation and oceans. Anomalies in atmospheric circulation include the atmospheric annular mode and the influence of cyclones, as well as influence of polar stratosphere vortices. For ocean anomalies, it includes warming of the subsurface of the Southern Ocean," Liu said.

In addition, the impact of the ozone hole over Antarctica is also an important factor, and most of these factors are related to human activities.

Researchers also warned that the drastic reduction in the Antarctic sea ice area may have serious consequences for penguins and other animals that breed and raise their offspring on the sea ice. It will reduce the amount of sunlight reflected back into space by the white ice to accelerate global warming as well.