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Rapid melting of Petermann Glacier signals even worse sea level rise

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A shocking study of Petermann Glacier in northwest Greenland by researchers from the University of California, Irvine (UCI) and NASA’s Jet Propulsion Laboratory has revealed a previously unknown interaction between ice and ocean.

This leads to the possibility that the climate community has been significantly underestimating the impact of polar ice deterioration on future sea level rise. This important discovery could have far-reaching implications for our understanding of climate change and its consequences.

The team of scientists used satellite radar data from three European missions to analyze the behavior of Petermann Glacier’s grounding line, where the ice detaches from the land bed and begins floating in the ocean.

What the researchers found at Petermann Glacier

Contrary to previous beliefs, they found that the grounding line shifts substantially during tidal cycles, allowing warm seawater to intrude and accelerate ice melt. The findings are detailed in a paper published in Proceedings of the National Academy of Sciences.

Lead author Enrico Ciraci, UCI assistant specialist in Earth system science and NASA postdoctoral fellow, explained: “Petermann’s grounding line could be more accurately described as a grounding zone because it migrates between 2 and 6 kilometers as tides come in and out. This is an order of magnitude larger than expected for grounding lines on a rigid bed.”

The traditional view of grounding lines beneath ocean-reaching glaciers did not account for this migration or ice melt during tidal cycles. However, the new study reveals that warm ocean water penetrates beneath the ice through preexisting subglacial channels, leading to the highest melt rates at the grounding zone.

As the glacier’s grounding line retreated nearly 4 kilometers (2½ miles) between 2016 and 2022, the researchers observed that warm water carved a 670-foot-tall cavity in the underside of the glacier. Remarkably, this cavity persisted throughout 2022.

Senior co-author Eric Rignot, UCI professor of Earth system science and NASA JPL research scientist, emphasized the significance of these findings, stating, “These ice-ocean interactions make the glaciers more sensitive to ocean warming.”

Models for future sea level rise must now be rebuilt

Current models do not include these ice-ocean dynamics, which, if accounted for, could increase projections of sea level rise by up to 200 percent – impacting not just Petermann Glacier but all glaciers ending in the ocean, including those in northern Greenland and Antarctica.

This discovery highlights the urgent need to update our understanding of glacier behavior in response to climate change.

The paper emphasizes that the Greenland ice sheet has lost billions of tons of ice to the ocean in recent decades, primarily due to warming of subsurface ocean waters – a consequence of Earth’s changing climate.

Rignot explains that exposure to ocean water vigorously melts ice at the glacier front, eroding resistance to the movement of glaciers over the ground and causing the ice to slide more quickly into the sea.

This groundbreaking research underscores the importance of refining our climate models to predict the future consequences of climate change and inform our response to this global crisis more accurately.

More about Petermann Glacier

Petermann Glacier is a large and significant glacier located in northwest Greenland. It is one of the largest floating ice shelves in the Northern Hemisphere, extending over an area of approximately 1,295 square kilometers.

The glacier is fed by the Greenland Ice Sheet and discharges into the Nares Strait, which separates Greenland from Ellesmere Island in the Canadian Arctic Archipelago. Petermann Glacier plays a vital role in draining the Greenland Ice Sheet and contributes to global sea level rise through the calving of icebergs and melting of its ice.

Several aspects make Petermann Glacier a subject of interest for climate scientists and glaciologists:

Ice shelf dynamics

The floating ice shelf at the terminus of Petermann Glacier is crucial for understanding the stability and dynamics of ice shelves. The interaction between the ice shelf and ocean waters provides insights into how ocean warming can impact ice shelf stability and glacier flow.

Calving events

Petermann Glacier has experienced several major calving events in recent years, with the most notable ones occurring in 2010 and 2012. These events resulted in the detachment of massive icebergs from the glacier’s floating ice shelf, raising concerns about the stability of the glacier and its contribution to sea level rise.

Grounding line migration

A recent study by researchers from the University of California, Irvine, and NASA’s Jet Propulsion Laboratory revealed that the grounding line of Petermann Glacier, where the ice detaches from the land bed and starts to float, migrates between 2 and 6 kilometers during tidal cycles. This previously unknown interaction between ice and ocean allows warm seawater to infiltrate and accelerate ice melt, potentially leading to underestimations of sea level rise caused by polar ice deterioration.

Climate change and sea level rise

Petermann Glacier, along with other glaciers in Greenland, is losing ice due to climate change. As a consequence of increasing temperatures and subsurface ocean warming, the glacier is melting at a faster rate, contributing to global sea level rise.

Research and monitoring

Due to its significance in understanding glacier dynamics, ice-ocean interactions, and the impact of climate change on ice sheets, Petermann Glacier has become a focal point for researchers and is closely monitored using satellite data, field measurements, and remote sensing techniques.

In summary, Petermann Glacier is a crucial component of the Greenland Ice Sheet and plays a vital role in understanding the impacts of climate change on glacier dynamics, ice-ocean interactions, and global sea level rise. Its behavior and stability have far-reaching implications for coastal communities and ecosystems worldwide.

More about global sea level rise

Global sea level rise is one of the most critical consequences of climate change, posing a significant threat to coastal ecosystems, infrastructure, and human populations. As Earth’s climate warms due to the increase in greenhouse gases, such as carbon dioxide and methane, two primary factors contribute to the rising sea levels: thermal expansion of ocean waters and the melting of land-based ice.

Thermal expansion

As ocean temperatures increase, seawater expands, occupying more volume. This expansion, known as thermal expansion, contributes to approximately half of the observed sea level rise. The upper layer of the ocean, which is in direct contact with the atmosphere, warms faster, causing water to expand and occupy more space, subsequently leading to a rise in sea level.

Melting of land-based ice

The melting of ice sheets and glaciers also contributes significantly to sea level rise. Ice sheets in Greenland and Antarctica contain vast amounts of frozen water, and their accelerated melting due to climate change has a substantial impact on global sea levels. Additionally, the melting of mountain glaciers worldwide, particularly in regions like the Himalayas, the Andes, and the Alps, adds to the rising sea levels.

Recent research suggests that ice loss from Greenland, Antarctica, and mountain glaciers has accelerated over the past few decades, causing the rate of global sea level rise to increase. From 1993 to 2021, the global sea level rose at an average rate of approximately 3.3 millimeters per year, and this rate is projected to increase further as climate change intensifies.

The consequences of sea level rise are far-reaching and pose significant risks to coastal communities, infrastructure, and ecosystems. Some of the most severe impacts include:

Flooding and erosion

As sea levels rise, the frequency and severity of coastal flooding and erosion increase, putting lives, property, and infrastructure at risk.

Saltwater intrusion

Rising sea levels can cause saltwater to intrude into freshwater resources, such as rivers and aquifers, threatening freshwater supplies and agricultural lands.

Loss of coastal habitats

Sea level rise can lead to the loss of vital coastal habitats, such as wetlands, mangroves, and coral reefs, which provide essential ecosystem services and act as natural barriers against storm surges and erosion.

Displacement of human populations

Low-lying coastal areas and small island nations are particularly vulnerable to sea level rise, which can lead to the displacement of millions of people, creating significant social, economic, and political challenges.

Mitigating global sea level rise requires urgent and concerted efforts to reduce greenhouse gas emissions, promote climate adaptation strategies, and improve our understanding of ice sheet dynamics and ocean processes. As the impacts of sea level rise are already being felt worldwide, it is crucial to act now to reduce future risks and protect vulnerable communities and ecosystems.

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Here’s how Helene and other storms dumped a whopping 40 trillion gallons of rain on the South

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More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.

That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.

“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”

The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.

Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.

Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.

Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.

Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.

Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.

“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”

The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.

North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.

Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”

Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.

Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.

For Dello, the “fingerprints of climate change” were clear.

“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”

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Follow AP’s climate coverage at https://apnews.com/hub/climate

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Follow Seth Borenstein on Twitter at @borenbears

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Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.

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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.

The Canadian Press. All rights reserved.

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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.”

The Canadian Press. All rights reserved.

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