Acidification greatest threat to the Southern Ocean

Along the western side of the Antarctic Peninsula, the dwindling numbers and sizes of once-vast Adelie penguin rookeries are testimony to the process

Mensun Bound vividly recalls the 1980s’ dive on a wreck near the Mediterranean island of Liperi. Plates, mugs, cups, lamps spilled out all over the bare seabed “as if the gods were at a meal and something spooked them, and they all dashed off. But in the process they knocked over the tables and sent all the crockery flying”.

But, while wrecks are normally small oases thriving with life, “everything was dead, dead, dead, dead”. Here they were diving in the crater of a still-live volcano and the bubbles of CO2 were acidifying, poisoning the water.

“I had a glimpse of what our seas can be like in 100 years . . . . it scared the daylights out of me.”

One of the world’s foremost marine archaeologists, Bound, who led last March’s successful expedition to find Ernest Shackleton’s Endurance, has written a riveting best-seller account of the search, The Ship Beneath the Ice. Acidification, he says, is the critical, mostly undiscussed, challenge facing the Antarctic region, just a few nautical miles south of where we meet in his Falklands/Malvinas home.


It is killing off the phytoplankton, highly sensitive to warming temperatures from climate change and acid variations, starving the krill, the vital food source of all the higher marine mammals, jeopardising even nature’s giant blue whales, the biggest animal on earth and exclusively a krill eater.

“Just one degree wipes out whole levels of phytoplankton, also nature’s real “carbon scrubbers” “.

Along the western side of the Antarctic Peninsula, the dwindling numbers and sizes of once-vast Adelie penguin rookeries are testimony to the process. Unlike their Gentoo cousins, these penguins are incapable of following the food, and so return futilely every year to what are becoming ghost communities.

And take the beautiful brittlestars, close relations of the starfish.

“They are heavily calcified, and when they put the brittlestars in salt water with the same pH level predicted for the end of this century, their arms, just the most incredibly flexible arms . . . snake-like . . . just curl up and drop off.”

They are heading for extinction.

Bound found shocking evidence all around him of the rolling ecological disaster facing the Antarctic when he returned this year [2022] to the Weddell Sea to find the Endurance’s resting place.

“I could not believe the extent to which the sea ice had not just shrunk but thinned . . . Three years ago we had to battle through multiyear ice but this year just sliced through it. Like a different world.”

It is a crisis not just, as we tend to think, for the world but the Continent.

Rising global sea levels, widely seen as the most serious threat from melting ice caps and glaciers, but on the Continent they also threaten habitats and the significant dilution of vital salt levels in the seas.

“This part of the world is where we produce most of the heavy cold salty water,“ Bound says.

It is vital to world weather.

“It spills out of the Weddell Sea and crosses the circumpolar region into the Atlantic and the Indian Ocean where it drives these great conveyor belts of rich cold heavy water which feed all these marine communities but drive the weather. ”

There is also growing evidence of other effects of man’s activities – a recent scientific survey warns that a huge range of human-generated noise, from shipping to sonar and echo sounding, key to subsea exploration, is likely to cause “acute to chronic impacts” in species ranging from tiny zooplankton to whales.

“Chronic exposure”, even to lower types of noise – which rips through water almost five times faster than air – could lead to permanent hearing loss, say the review authors.

Bound admits that his exploration may be part of that problem: “What is that doing to the whales and possibly some of the seals? I just don’t know. I carry a lot of guilt with me these days. Our generation have done such a good job of screwing up the planet.”

A counsel of despair? We may be too late.

“We can’t deacidify oceans even if we can clean up the atmosphere . . . well yeah, perhaps one of the reasons we don’t talk about it very much is nobody has solutions . . . yes, there is still hope but as I look at these things I struggle to see that.”

Wrapping around the bottom ten per cent of the globe, Antarctica and its Southern Ocean are five times bigger than Australia, a hostile, yet-untamed but achingly beautiful place. The last great wilderness, but not, definitely not, empty – we have, only a few days into our visit, already seen pods of whales, albatross and penguin rookeries, sealions sleeping on the quayside . . . We must leave them alone.