Newly discovered deep seabed channels beneath Thwaites Glacier in West Antarctica may be the pathway for warm ocean water to melt the underside of the ice. Data from two research missions, using aircraft and ship, are helping scientists to understand the contribution this huge and remote glacier is likely to make to future global sea level rise.
Researchers from UK and US International Thwaites Glacier Collaboration (ITGC), collected data from the glacier and adjoining Dotson and Crosson ice shelves during January-March 2019. While one team collected airborne data flying over the glacier and ice shelf in a British Antarctic Survey Twin Otter aircraft, the other mapped the sea floor at the ice front from the US Antarctic Program icebreaker RV Nathaniel B Palmer.
Publishing this month in the journal The Cryosphere the two research papers describe the discovery. Thwaites Glacier covers 192,000 square kilometres (74,000 square miles) – the size of Great Britain or the US state of Florida—and is particularly susceptible to climate and ocean changes.
Over the past 30 years, the overall rate of ice loss from Thwaites and its neighbouring glaciers has increased more than 5-fold. Already, ice draining from Thwaites into the Amundsen Sea accounts for about four percent of global sea-level rise. A run-away collapse of the glacier could lead to a significant increase in sea levels of around 65 cm (25 inches) and scientists want to find out how quickly this could happen.
Lead author Dr. Tom Jordan, an aero-geophysicist at British Antarctic Survey (BAS), who led the airborne survey, says:
“It was fantastic to be able to map the channels and cavity system hidden beneath the ice shelf; they are deeper than expected—some are more than 800 metres deep. They form the critical link between the ocean and the glacier.
“The offshore channels, along with the adjacent cavity system, are very likely to be the route by which warm ocean water passes underneath the ice shelf up to the grounding line, where the ice meets the bed.”
Dave Porter at LDEO Columbia University, who flew over Thwaites Glacier for the airborne survey, says:
“Flying over the recently-collapsed ice tongue and being able to see first-hand the changes occurring at Thwaites Glacier was both awe inspiring and disconcerting, but also gratifying to know the airborne data we were collecting would help reveal the hidden structures below.”
Exceptional sea-ice break up in early 2019 enabled the team on the RV Nathaniel B Palmer to survey over 2000 square kilometres of sea floor at the glacier’s ice front. The area surveyed had previously been hidden beneath part of the floating ice shelf extending from Thwaites Glacier, which broke off in 2002, and in most subsequent years the area was inaccessible due to thick sea-ice cover. The team’s findings reveal the sea floor is generally deeper and has more deep channels leading towards the grounding line under the ice shelf than was previously thought.
Lead author, Dr. Kelly Hogan, is a marine geophysicist at BAS. She was part of the team surveying the seabed. She says:
“We found the coastal sea floor, which is incredibly rugged, is a really good analogue for the bed beneath the present-day Thwaites Glacier both in terms of its shape and rock type. By examining retreat patterns over this sea-floor terrain we will be able to help numerical modellers and glaciologists in their quest to predict future retreat.
“This research has filled a critical data gap. Together the new coastal sea floor maps and the cavity maps track the deep channels for over 100 km to where the glacier sits on the bed. For the first time we have a clear view of the pathways along which warm water can reach the underside of the glacier, causing it to melt and contribute to global sea-level rise.”
More information:
New gravity-derived bathymetry for the Thwaites, Crosson, and Dotson ice shelves revealing two ice shelf populations, The Cryosphere (2020). DOI: 10.5194/tc-14-2869-2020
Revealing the former bed of Thwaites Glacier using sea-floor bathymetry: implications for warm-water routing and bed controls on ice flow and buttressing, The Cryosphere (2020). doi.org/10.5194/10.5194/tc-14-2883-2020
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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.
