Don’t Step on the Crack at Petermann Glacier

A satellite image of the crack in Petermann Glacier (Source: Stef Lhermitte/Twitter).

Cracks in ice shelves have appeared in disaster movies as ominous signs of global warming. One memorable instance occurs in The Day After Tomorrow when a paleoclimatologist is drilling ice cores at the Larsen Ice Shelf. The shelf breaks apart, leading to a series of cataclysmic climate events that disrupt the North Atlantic Ocean circulation. In July, a real- life crack appeared at Petermann Glacier in Greenland and has been growing steadily ever since. Two scientists, Andreas Muenchow and Keith Nicholls, are investigating the crack and hypothesize that it is caused by an increase in air and ocean temperatures.

An image of ice breaking off the Petermann Glacier in 2012 (Source: NASA Goddard Space Flight Center/Flickr).

Petermann Glacier connects the Greenland ice sheet to the Arctic Ocean at 81°N. It is approximately 43 miles long and nearly 10 miles wide. This is not the first crack or full break of ice at Petermann Glacier, according to a Washington Post article by Chris Mooney. Since 2010, entire slabs of the Petermann glacier have broken off.

In fact, during two occasions, the glacier lost an area of ice six times the size of Manhattan, according to Mooney. This loss raises enormous concern because the glacier serves to slow down the flow of ice downhill from the Greenland ice sheet into the ocean. For this reason, experts call Petermann a “floodgate.” If the glacier that sits behind Petermann melts, it could raise sea levels by about a foot.

A close-up view of the new crack in the Petermann Glacier (Source: NASA Operation IceBridge/Facebook).

A recent paper published in the Geophysical Research Letters describes this type of calving at Petermann as common. The authors explain that it is usually assumed that ocean-ice dynamics are not involved. However, evidence from the Pine Island Glacier in West Antarctica found that ocean forcing can play a role in the melting.

Muenchow and Nicholls expect similar dynamics are occurring with Petermann Glacier. They have been on several expeditions to the glacier in order to measure ocean temperatures underneath the shelf itself. They want to see if rising ocean temperatures are also detrimental to the glacier and causing the melting from below.

If warm ocean water were melting the base of the glacier, it would only accelerate the destruction of Petermann. While it is extremely difficult to know definitively, they hypothesize Petermann’s river and the channel beneath it are playing a role in the melting.

Data from 2015 and 2016 demonstrates that the temperatures of the warm Atlantic layer in the ocean have increased. With both air and ocean temperatures getting warmer, it is unclear how much longer Petermann Glacier will be intact, leaving frightening implications for the melting of the enormous glacier behind it. The crack in the Petermann Glacier and the possible ensuing events show that news from the ice can sometimes be just as scary as the scenes in disaster movies.

Snow Bacteria, A Pandora’s Box?

Stills for the movie “The Day after Tomorrow” (source: Day After Tomorrow Images).
Still from the film “The Day after Tomorrow” (source: Day After Tomorrow Images).

Remember the famous scene in the movie “The Day after Tomorrow” when the flood comes, along with storms and a tsunami, and hundreds of people are killed at the dawn of a new ice age? In that scene, the bacteria once frozen in the world’s glaciers is released due to global warming. It turns out that fateful scenario may one day come true, according to recent research by Yongqin Liu, a scientist at the Institute of Tibetan Plateau Research (ITPR) in China.

Institute of Tibetan Plateau Research of Chinese Academy of Sciences (sourece: ITPR).
The Institute of Tibetan Plateau Research at the Chinese Academy of Sciences (source: ITPR).

You might be surprised or confused about how bacteria could survive in extremely cold conditions for thousands of years. The reason bacteria and other viruses can remain dormant in the ice layer is because some bacteria are cold-adapted. Glaciers can serve as excellent locations for such bacteria to survive during long periods of extreme cold.

“A frozen condition is not optimal for most creatures on earth, but it does provide a satisfactory living environment for some microorganisms,” said Liu.

Location of the Guoqu and East Rongbuk Glacier (source: Liu et al.).
The location of the Guoqu and East Rongbuk glaciers (source: Liu et al.).

 

In the last few decades, scientists at the Institute of Tibetan Plateau Research have been studying snow bacteria in the Tibetan Plateau. Liu is one of the leading scholars on the team. For instance, earlier in 2008, she conducted research about snow bacterial abundance and diversity at the Guoqu Glacier and the East Rongbuk Glacier.

By using a special approach (16S rRNA gene clone library and flow cytometry), Liu and her colleagues observed different patterns of seasonal variation at the two glaciers. They found that bacterial diversity at the glaciers also exhibits different responses to various environmental conditions.

In an interview with GlacierHub, Liu explained, “Currently, we are focusing on the diversity of snow bacteria from glaciers in the Tibetan Plateau environment. Our latest paper was about snow bacteria on the Zangser Kangri Glacier. We managed to identify the major sources of the bacteria and make a comparison of snow bacterial abundance between the Zangser Kangri Glacier and other glaciers of the Tibetan Plateau.”

Scientists are collecting ice-core at Tibet (source: ITPR).
Scientists collecting ice cores in Tibet (source: ITPR).

Liu is one of many scientists fascinated with snow bacteria. But others might feel it is irrelevant to their modern life since these bacteria remain in a deep and frozen sleep. Shuhong Zhang, a researcher at Cold and Arid Regions Environmental and Engineering Research Institute of the Chinese Academy of Sciences, believes otherwise.

“One impact of climate change is the rapid shrinking of glaciers,” Zhang writes in an article. “This results in microorganisms getting deposited into glacial snow or ice and being exposed to new environments such as glacier forelands.”

Shlomit Paz, a scientist from University of Haifa, also found that the West Nile virus, one of the world’s most widely distributed viruses, could be propelled by global warming. “Recent changes in climatic conditions, particularly increased snowmelt and glacier retreat, contributed to the maintenance of the West Nile Virus in various locations in southern Europe, western Asia, the eastern Mediterranean, the Canadian Prairies, parts of the USA and Australia,” Paz writes. “As predictions show that the current trends are expected to continue, for better preparedness, any assessment of future transmission of West Nile Virus should take into consideration the impacts of climate change.”

Ancient bacteria found in glaciers (source: Sina Tech).
Ancient bacteria found in a glacier (source: Sina Tech).

So perhaps one day, without actions taken to mitigate climate change, a Pandora’s box will be opened. In the ancient Greek myth, all the evils fly out of the box. And now, climate change may set lethal bacteria and viruses free, posing a new, catastrophic threat to human beings.