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Alaska’s top-heavy glaciers are approaching an irreversible tipping point

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The melting of one of North America’s largest icefields has accelerated and could soon reach an irreversible tipping point. That’s the conclusion of new research colleagues and I have published on the Juneau Icefield, which straddles the Alaska-Canada border near the Alaskan capital of Juneau.

In the summer of 2022, I skied across the flat, smooth and white plateau of the icefield, accompanied by other researchers, sliding in the tracks of the person in front of me under a hot sun. From that plateau, around 40 huge, interconnected glaciers descend towards the sea, with hundreds of smaller glaciers on the mountain peaks all around.

Our work, now published in Nature Communications, has shown that Juneau is an example of a climate “feedback” in action: as temperatures are rising, less and less is remaining through the summer (technically: the “end-of-summer snowline” is rising). This in turn leads to ice being exposed to sunshine and higher temperatures, which means more melt, less snow, and so on.

Like many Alaskan glaciers, Juneau’s are top-heavy, with lots of ice and snow at above the end-of-summer snowline. This previously sustained the glacier tongues lower down. But when the end-of-summer snowline does creep up to the top plateau, then suddenly a large amount of a top-heavy glacier will be newly exposed to melting.

That’s what’s happening now, each summer, and the glaciers are melting much faster than before, causing the icefield to get thinner and thinner and the plateau to get lower and lower. Once a threshold is passed, these feedbacks can accelerate melt and drive a self-perpetuating loss of snow and ice which would continue even if the world were to stop warming.

Ice is melting faster than ever

Using satellites, photos and old piles of rocks, we were able to measure the ice loss across Juneau Icefield from the end of the last “Little Ice Age” (about 250 years ago) to the present day. We saw that the glaciers began shrinking after that cold period ended in about 1770. This ice loss remained constant until about 1979, when it accelerated. It accelerated again in 2010, doubling the previous rate. Glaciers there shrank five times faster between 2015 and 2019 than from 1979 to 1990.

Our data shows that as the snow decreases and the summer melt season lengthens, the icefield is darkening. Fresh, white snow is very reflective, and much of that strong solar energy that we experienced in the summer of 2022 is reflected back into space. But the end of summer snowline is rising and is now often occurring right on the plateau of the Juneau Icefield, which means that older snow and glacier ice is being exposed to the sun. These slightly darker surfaces absorb more energy, increasing snow and ice melt.

As the plateau of the icefield thins, ice and snow reserves at higher altitudes are lost, and the surface of the lowers. This will make it increasingly hard for the icefield to ever stabilise or even recover. That’s because warmer air at low elevations drives further melt, leading to an irreversible tipping point.

Longer-term data like these are critical to understand how glaciers behave, and the processes and tipping points that exist within individual glaciers. These complex processes make it difficult to predict how a glacier will behave in future.

The world’s hardest jigsaw

We used satellite records to reconstruct how big the glacier was and how it behaved, but this really limits us to the past 50 years. To go back further, we need different methods. To go back 250 years, we mapped the ridges of moraines, which are large piles of debris deposited at the glacier snout, and places where glaciers have scoured and polished the bedrock.

To check and build on our mapping, we spent two weeks on the icefield itself and two weeks in the rainforest below. We camped among the moraine ridges, suspending our food high in the air to keep it safe from bears, shouting to warn off the moose and bears as we bushwhacked through the rainforest, and battling mosquitoes thirsty for our blood.

We used to reconstruct the icefield in the 1940s and 1970s, in the era before readily available satellite imagery. These are high quality photos, but were taken before global positioning systems made it easy to locate exactly where they were taken.

A number also had some minor damage in the intervening years—some Sellotape, a tear, a thumb print. As a result, the individual images had to be stitched together to make a 3D picture of the whole icefield. It was all rather like doing the world’s hardest jigsaw puzzle.

Work like this is crucial as the world’s glaciers are melting fast—all together they are currently losing more mass than the Greenland or Antarctic ice sheets, and thinning rates of these glaciers worldwide has doubled over the past two decades.

Our longer time series shows just how stark this acceleration is. Understanding how and where “feedbacks” are making glaciers melt even faster is essential to make better predictions of future change in this important region.

More information:
Bethan Davies et al, Accelerating glacier volume loss on Juneau Icefield driven by hypsometry and melt-accelerating feedbacks, Nature Communications (2024). DOI: 10.1038/s41467-024-49269-y

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‘Big Sam’: Paleontologists unearth giant skull of Pachyrhinosaurus in Alberta

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It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.

On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.

They call it “Big Sam.”

The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.

It didn’t die alone.

“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.

She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”

“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.

The head alone, she said, is about the size of a baby elephant.

The discovery was a long time coming.

The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.

“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.

When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”

“It contains about 100 to 300 bones per square metre,” she said.

Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.

About a year ago, they found the second adult: Big Sam.

Bamforth said both dinosaurs are believed to have been the elders in the herd.

“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.

“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”

The genders of the two adults are unknown.

Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.

The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.

She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.

“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.

“It’s pretty exciting.”

This report by The Canadian Press was first published Sept. 25, 2024.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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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.”

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B.C. sets up a panel on bear deaths, will review conservation officer training

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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.

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