Scientists may just have identified Thwaites Glacier’s Achilles heel.
This Antarctic colossus is melting at a rapid rate, dumping billions of tonnes of ice in the ocean every year and pushing up global sea-levels.
Now, a UK-US team has surveyed the deep seafloor channels in front of the glacier that almost certainly provide the access for warm water to infiltrate and attack Thwaites’ underside.
It’s information that will be used to try to predict the ice stream’s future.
“These channels had not been mapped before in this kind of detail, and what we’ve discovered is that they’re actually much bigger than anyone thought – up to 600m deep. Think of six football pitches back to back,” said Dr Kelly Hogan from the British Antarctic Survey (BAS).
“And because they are so deep, and so wide – this allows a lot more water to get at, and melt, Thwaites’ floating front as well as its ice that rests on the seabed,” she told BBC News.
Why is Thwaites Glacier so important?
Flowing off the west of the Antarctic continent, Thwaites is almost as big as Great Britain.
It’s a majestic sight, with its buoyant front, or “ice shelf”, pushing far out to sea and kicking off huge icebergs. But satellite monitoring indicates this glacier is melting at an accelerating rate.
In the 1990s it was losing just over 10 billion tonnes of ice a year. Today, it’s more like 80 billion tonnes. The cause of the melting is thought to be the influx of relatively warm bottom-water drawn in from the wider ocean.
Currently, Thwaites’ ice loss contributes approximately 4% to the annual rise in global sea-levels, with the potential to add 65cm in total should the whole glacier collapse.
No-one thinks this will happen in the short-to-medium term, but Thwaites is considered particularly vulnerable in a warming world, and scientists would like to know precisely how fast any changes might occur.
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What does the latest research show?
The UK and the US joined forces in 2019 to investigate Thwaites.
Their scientists sailed a ship equipped with an echo-sounder right up to the glacier’s ice cliffs, to trace the shape of the seabed below.
A plane was also flown back and forth across the shelf to measure small variations in the pull of gravity. These deviations reflected the seafloor’s undulations beneath the shelf.
The two datasets taken together now provide the best view yet of Thwaites’ underlying topography. They trace the path of a network of deep channels that cut through a ridge before joining up to form a major cavity under the ice shelf.
“The connected channels that we’ve mapped in detail for the first time are the potential pathways for deep-ocean warm water to get in and do damage at that point where the glacier is still grounded on the seabed, where it begins to lift up and float,” explained BAS colleague Dr Tom Jordan, “but also to melt the base of the ice shelf, which if you weaken will make the ice further upstream in the glacier flow faster.”
How will the new survey information be used?
Scientists need real-world data to corral their models so that when they run simulations of possible future behaviour, they get realistic outcomes.
The new information refines the volumes for ingressing warm water that can be considered possible under different scenarios.
In conducting their survey, scientists also now have a better idea of the general roughness of the seafloor.
This tells them about the sorts of speeds ice further back in the glacier can achieve as it slides across rock and sediment. What the researchers have produced, if you like, is a kind of “stickiness index” to additionally constrain the computer models.
What’s likely to happen in the near future?
At the moment, the eastern side of the ice shelf is hooked on to a large ridge, which gives it stability. But the current melting trend would suggest this situation won’t last much longer, says BAS’s Dr Robert Larter.
“When the Eastern Ice Shelf becomes unpinned, the ice will spread out and thin, eventually breaking up, as we can see is happening right now on the (central) glacier tongue,” he told BBC News. “Even before ice shelf break-up, the unpinning and thinning will reduce the buttressing effect of the ice shelf on the glacier upstream of it, resulting in increased ice flow velocity. This in turn will further accelerate thinning of the glacier and grounding line retreat.”
British and American scientists have had to temporarily suspend their investigations at Thwaites because of the Covid-19 crisis.
Teams were due to head back to the glacier this austral summer, but the location’s remoteness means the risks are too great should anyone fall ill. Once the coronavirus outbreak has been properly contained, the scientists will return, however.
“It’s amazing to go to a place like Thwaites to see the changes taking place right before your eyes,” said Dr Hogan. “When we were there in 2019, we were able to get right up to the ice shelf cliffs, and the reason we could do that and make our observations was because the icebergs and sea-ice that have always been there historically are starting to disappear.”
The latest research is published in two papers in the journal The Cryosphere, and can be accessed here and here.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
