Today’s ice sheet in Antarctic and that during the Last Interglacial when seaways allowed connections between octopus populations.
Scientists investigating how Antarctica’s ice sheets retreated in the deep past have turned to an innovative approach: studying the genes of octopuses that live in its chilly waters.
A new analysis published Thursday in Science finds that geographically-isolated populations of the eight-limbed sea creatures mated freely around 125,000 years ago, signaling an ice-free corridor during a period when global temperatures were similar to today.
The findings suggest the West Antarctic Ice Sheet (WAIS) is closer to collapse than previously thought, threatening 3.3-5 meters of long term sea level rise if the world is unable to hold human-caused warming to the 1.5 degrees Celsius target of the Paris Agreement, said the authors.
Lead author Sally Lau of James Cook University in Australia told AFP that as an evolutionary biologist focused on marine invertebrates, “I understand and then apply DNA and biology as a proxy of changes to Antarctica in the past.”
Turquet’s octopus made an ideal candidate for studying WAIS, she said, because the species is found all around the continent and fundamental information about it has already been answered by science, such as its 12-year-lifespan, and the fact it emerged some four million years ago.
About half-a-foot (15 centimeters) long excluding the arms and weighing around 1.3 pounds (600 grams), they lay relatively few, but large eggs on the bottom of the seafloor. This means parents must put significant effort into ensuring their offspring hatch—a lifestyle that prevents them traveling too far away.
They are also limited by circular sea currents, or gyres, in some of their modern habitats.
‘Tipping point close’
By sequencing the DNA across genomes of 96 samples that were generally collected inadvertently as fishing bycatch and then left in museum storage over the course of 33 years, Lau and colleagues found evidence of trans-West Antarctic seaways that once connected the Weddell, Amundsen and Ross seas.
About half-a-foot (15 centimeters) and weighing around 1.3 pounds (600 grams), Turquet’s octopuses lay relatively few, but large eggs on the bottom of the seafloor which means parents must put significant effort into ensuring their offspring hatch.
The history of genetic mixing indicated WAIS collapsed at two separate points—first in the mid-Pliocene, 3-3.5 million years ago, which scientists were already confident about, and the last time in a period called the Last Interglacial, a warm spell from 129,000 to 116,000 years ago.
“This was the last time the planet was around 1.5 degrees warmer than pre-industrial levels,” said Lau. Human activity, primarily burning fossil fuels, has so far raised global temperatures by 1.2C compared to the late 1700s.
There were a handful of studies prior to the new Science paper that also suggested WAIS collapsed some time in the past, but they were far from conclusive because of the comparatively lower resolution genetic and geological data.
“This study provides empirical evidence indicating that the WAIS collapsed when the global mean temperature was similar to that of today, suggesting that the tipping point of future WAIS collapse is close,” the authors wrote.
Sea level rise of 3.3 meters would drastically alter the world map as we know it, submerging low-lying coastal areas everywhere.
Writing in an accompanying commentary piece, Andrea Dutton of the University of Wisconsin-Madison and Robert DeConto of the University of Massachusetts, Amherst described the new research as “pioneering,” adding it posed intriguing questions about whether ancient history will be repeated.
They flagged however that several key questions remained unanswered—such as whether the past ice sheet collapse was caused by rising temperatures alone, or whether other variables like changing ocean currents and complex interactions between ice and solid Earth were also at play.
It’s also not clear whether the sea level rise would be drawn out over millennia or occur in more rapid jumps.
But uncertainties such as these can’t be an excuse for inaction against climate change “and this latest piece of evidence from octopus DNA stacks one more card on an already unstable house of cards,” they wrote.
More information:
Sally C. Y. Lau et al, Genomic evidence for West Antarctic Ice Sheet collapse during the Last Interglacial, Science (2023). DOI: 10.1126/science.ade0664
Citation:
Antarctic octopus DNA reveals ice sheet collapse closer than thought (2023, December 21)
retrieved 21 December 2023
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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.
