Antarctic expedition scientists trapped in ice

Antarctic Ice rescue

During the morning hours on January 2, the crew of an icebreaker trapped near Antarctica was airlifted out of their ice-bound ship. The crew was partially composed of scientists, partially composed of people with public interest, including at least one photographer.

The way this ship became trapped is actually interesting as it provides a lot of insight into how Antarctica and the surrounding sea ice operates.

In this image, taken by the photographer, you see a giant iceberg. This was part of the icepack that trapped them, but the ice actually still was somewhat able to move around them for a long portion of their voyage.

Sea ice around Antarctica forms because of the ice sheets on the continent. Antarctica is very close to isolated from the rest of the world’s oceans by a single circulation pattern – the Antarctic Circumpolar Current.

Because of that current, the waters close to Antarctica don’t mix easily with the waters of the rest of the ocean. Instead, when ice melts at the Antarctic shorelines or when it snows or rains…it’s just adding fresh water. This process makes the surface waters less salty and makes it easier for it to refreeze or for separate chunks of ice to be packed together.

A strong, cold wind and the surrounding icebergs were the culprit. The thick icebergs, like this one, are created when ice breaks off from the thick glaciers on the continent. These icebergs are pushed around by the wind until they break off into the open ocean. Sometimes, a strong wind can cause them to pile up in a single area, especially if there’s a nearby source. Most of the ice that packed in this ship was ice that recently calved off of the nearby Mertz glacier; a major continental source of ice.

Put together the combination of a strong wind, icebergs piling up in a single area, and cold surface waters, and you have all the ingredients necessary to pack ice together into a layer thicker than an icebreaker can penetrate. This thick ice would only be a local phenomenon; it wouldn’t cover the entire ocean, just certain areas, but it could certainly be hazardous to oceangoing traffic.

It’s hard to know from here how fast this could happen, but I’d imagine it could take only a few hours for the ice to pile up and be compacted into a single block. Ice can be easily compacted by a strong wind, so the conditions at this one spot turned out to be perfect. A strong wind and a substantial nearby supply of ice.

As we’ve pointed out here at the Earth Story, the connection between a single point on Antarctica’s sea ice and the wider climate is a complicated one, as Antarctica is very isolated and is also impacted by changes such as the ozone hole. In fact, as we discuss here; the presence of the ozone hole can help drive the type of strong winds that contributed to the formation of this icepack ( https://www.facebook.com/TheEarthStory/ ... 3590329689 ).

If you take just one message from this post, it’s that the formation of sea ice in single areas around Antarctica is driven by very specific phenomena and all researchers, whether on boats or in labs, need to keep working to better understand these local effects. Cruises like this one, in fact, are going to continue to be necessary to understand how the sea ice in Antarctica evolves with time.

-JBB

Image credit: BBC News
http://www.bbc.co.uk/news/science-environment-25576712

Rescue report and more photos:
http://www.theguardian.com/science/anta ... e-coverage

www.theguardian.com/environment/2014/ja ... e-sceptics