VIDEO: Diving under the Antarctic ice sheet in minus 2 degree waters

A diver enters an ice hole near Australia’s Casey station. Image: Kristin Raw/Australian Antarctic Division.

Australian researchers cut a hole through a thick sheet of ice and sent divers into minus 2 degree waters to complete the world’s first seafloor ocean acidification experiment in Antarctica near Casey station.

“The human body can only take those sort of temperatures for about an hour, so we had to continually rotate divers, and ensure they could be warmed up quickly once out of the water,” says Dr Jonny Stark, Australian Antarctic Division Project Leader.

The 15-member team did more than 200 dives and spent about 200 hours under the ice sheet. Watch them cut the ice hole and descend into the Antarctic waters:

The study mimicked future ocean conditions, predicted to be two and half times more acidic by 2100, and involved deploying four acrylic two-metre long chambers on the seafloor.

Carbon dioxide-enriched seawater was then pumped into two of the chambers through a series of 40 metre long ducts or slinkies. Regular seawater was pumped through the other two chambers for comparison.

There are no conclusive results yet but initial indications are that the photosynthesis of some of the tiny marine plants changed in response to the more acidic seawater.

The Southern Ocean absorbs 40% of the global ocean uptake of carbon dioxide and polar waters are acidifying at twice the rate of tropical waters.

Thruster tube on sea floor. Image: Glenn Dunshea / Australian Antarctic Division

“The rate and scale of the changes we are seeing in the Southern Ocean are unprecedented, so it’s critical that we are able to get a clearer picture of how ocean acidification will impact the marine ecosystems into the future,” says Stark.

The experiment was one of 28 research projects conducted in Antarctica and on sub Antarctic Macquarie Island over summer.

Descending through the ice hole. Australian Antarctic Division

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