Rising Antarctic ice melt will dramatically slow global ocean flows: study
Rising Antarctic ice melt will dramatically slow global ocean flows: study
In this Jan. 26, 2015 photo, pieces of thawing ice are scattered along the beachshore at Punta Hanna, Livingston Island, South Shetland Island archipelago, Antarctica. Water is eating away at the Antarctic ice, melting it where it hits the oceans. As the ice sheets slowly thaw, water pours into the sea, 130 billion tons of ice (118 billion metric tons) per year for the past decade, according to NASA satellite calculations. (AP Photo/Natacha Pisarenko)
The "overturning circulation" of the oceans, driven by the movement of denser water towards the sea floor, helps deliver heat, carbon, oxygen and vital nutrients around the globe.
But deep ocean water flows from the Antarctic could decline by 40 per cent by 2050, according to a study published on Wednesday in the journal Nature.
"That's stunning to see that happen so quickly," said Alan Mix, a paleoclimatologist at Oregon State University and co-author on the latest Intergovernmental Panel on Climate Change assessments, who was not involved in the study. "It appears to be kicking into gear right now. That's headline news."
As temperatures rise, freshwater from Antarctica's melting ice enters the ocean, reducing the salinity and density of the surface water and diminishing that downward flow to the sea's bottom.
While past research has looked at what could happen to similar overturning circulation in the North Atlantic - the mechanism behind the doomsday scenario that would see Europe suffer from an Arctic blast as heat transport falters - less has been done on Antarctic bottom water circulation.
Scientists relied on around 35 million computing hours over two years to crank through a variety of models and simulations up to the middle of this century, finding deepwater circulation in the Antarctic could weaken at twice the rate of decline in the North Atlantic.
"They are massive volumes of water... and they are bits of the ocean that have been stable for a long time," said study co-author Matthew England, an oceanographer at the University of New South Wales, in a news briefing.
BASE OF THE FOOD CHAIN
The effect of meltwater on global ocean circulation has not yet been included in the complex models used by the IPCC to describe future climate change scenarios, but it is going to be considerable, England said.
Ocean overturning allows nutrients to rise up from the bottom, with the Southern Ocean supporting about three-quarters of global phytoplankton production, the base of the food chain, said a second study co-author, Steve Rintoul.
"If we slow the sinking near Antarctica, we slow down the whole circulation and so we also reduce the amount of nutrients that get returned from the deep ocean back up to the surface," said Rintoul, a fellow at Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO).
The study's findings also suggest the ocean would not be able to absorb as much carbon dioxide as its upper layers become more stratified, leaving more CO2 in the atmosphere.
The study showed that warm water intrusions in the western Antarctican ice shelf would increase, but it did not look at how this might create a feedback effect and generate even more melting.
"It doesn't include the disaster scenarios," said Mix. "In that sense, it's actually kind of conservative."
Reporting by David Stanway, Additional reporting by Gloria Dickie in London, Editing by Alex Richardson
A U.S. federal court unsealed an indictment against Donald Trump on Friday detailing 37 charges against the former president for retaining classified government documents after he left office in 2021.
Air Canada has rejected compensation claims from some travellers who were among the thousands affected by flight delays caused by computer problems in recent weeks -- a response it now calls 'erroneous,' with cash offers en route.
Amid raging wildfires in western and eastern provinces, vice-president of the Insurance Bureau of Canada, Craig Stewart, shares what residents need to know about wildfire policy coverage.
Environment Canada has been advising people to check the Air Quality Health Index as wildfire smoke blanketed large swaths of Canada in recent days, but even without wildfires, the index can be a useful tool to monitor air pollution.
Anthaea-Grace Patricia Dennis is not your typical 12-year-old. She is a child prodigy who's about to become the youngest Canadian to ever graduate from university.
The father of Tori Stafford, an Ontario girl who was murdered in 2009, says the latest decision to transfer convicted killer Paul Bernardo to a medium-security prison is a 'slap in the face' to all murder victims' families.
Two years after two statues were knocked down and damaged at the Manitoba Legislature, one is now back up and Indigenous leaders are upset by the decision.
Air Canada has rejected compensation claims from some travellers who were among the thousands affected by flight delays caused by computer problems in recent weeks -- a response it now calls 'erroneous,' with cash offers en route.
The father of Tori Stafford, an Ontario girl who was murdered in 2009, says the latest decision to transfer convicted killer Paul Bernardo to a medium-security prison is a 'slap in the face' to all murder victims' families.
Canada's unemployment rate ticked up in May for the first time in nine months, but forecasters say the Bank of Canada will have to see more softening in the economy before it takes it takes a step back from raising interest rates.
The number of active wildfires in northern Ontario has grown, but more of them are under control as the fight continues. Here is what you need to know.
France is calling him "the backpack hero," a young Catholic pilgrim on a walking tour of cathedrals who came face to face with the man who stabbed several children in a park in Annecy.
Philippine troops, police and rescue workers began forcibly evacuating residents near Mayon Volcano on Friday as its increasing unrest indicated a violent eruption of one of the country's most active volcanoes is possible within weeks or days.
Ukraine's domestic security service said on Friday it had intercepted a telephone call proving a Russian 'sabotage group' blew up the Kakhovka hydroelectric station and dam in southern Ukraine.
France's president travelled Friday to the side of families traumatized by the savage stabbings of four very young children, all said to be in stable condition after emergency surgery, while investigators worked to unravel the motives of a Syrian man taken into custody.
Pope Francis was "progressively improving" and sitting in an armchair working Friday, following surgery to remove intestinal scar tissue and repair a hernia in his abdominal wall, the Vatican said.
Canada requested use of the European Union's compound in Kabul to help with tasks such as fingerprinting for those fleeing Afghanistan, according to documents obtained by The Canadian Press.
The Supreme Court of Canada will not hear the appeal of an Alberta woman who was unwilling to be vaccinated in order to get a life-saving organ transplant.
A little white pill has given Syrian President Bashar Assad powerful leverage with his Arab neighbours, who have been willing to bring him out of pariah status in hopes he will stop the flow of highly addictive Captagon amphetamines out of Syria.
Canadians who make content online are to be excluded from future regulations that the Liberal government is imposing on digital giants, a new draft policy shows.
Facebook owner Meta Platforms on Thursday gave employees a sneak peek at a series of AI tools it was building, including ChatGPT-like chatbots planned for Messenger and WhatsApp that could converse using different personas.
Scientists have documented the first-known instance of a 'virgin birth' by a crocodile, which had been living in isolation for 16 years at Costa Rican zoo, according to a study published Wednesday.
Daily U.S. sign-ups for Netflix have jumped in the first few days after the streaming giant's password-sharing crackdown came into effect on May 23, data from research firm Antenna showed.
A Tennessee man pleaded guilty Friday to helping two other men charged with fatally shooting rapper Young Dolph in a daytime ambush at a Memphis bakery.
Air Canada has rejected compensation claims from some travellers who were among the thousands affected by flight delays caused by computer problems in recent weeks -- a response it now calls 'erroneous,' with cash offers en route.
Canada's unemployment rate ticked up in May for the first time in nine months, but forecasters say the Bank of Canada will have to see more softening in the economy before it takes it takes a step back from raising interest rates.
WestJet and Swoop pilots have ratified a new collective agreement after a bargaining process that saw the threat of a strike snarl many Canadians' long weekend plans last month.
Rescuers in Washington state are praising the resourcefulness of a 10-year-old girl who survived on her own for more than 24 hours in the rugged terrain of the Cascade mountains after getting lost while out with her family.
The April Facebook post hardly seemed like national news at the time for Deptford Little League president Don Bozzuffi. He'd lost patience when two umpires resigned in the wake of persistent spectator abuse. So he wrote an updated code of conduct.
Ford has planned a return to the 24 Hours of Le Mans with its iconic Mustang muscle car next year under a massive rebranding of Ford Performance aimed at bringing the automotive manufacturer "into the racing business."
A group of climate activists claimed responsibility on Wednesday for deflating the tires of sport utility vehicles in Denmark's capital. More than 100 vehicles were vandalized, police said.
In this Jan. 26, 2015 photo, pieces of thawing ice are scattered along the beachshore at Punta Hanna, Livingston Island, South Shetland Island archipelago, Antarctica. Water is eating away at the Antarctic ice, melting it where it hits the oceans. As the ice sheets slowly thaw, water pours into the sea, 130 billion tons of ice (118 billion metric tons) per year for the past decade, according to NASA satellite calculations. (AP Photo/Natacha Pisarenko)
