Tag: shoreline
Antarctic Ice Shelves Melting 70 Percent Faster In Last Decade, Study Shows

Antarctic Ice Shelves Melting 70 Percent Faster In Last Decade, Study Shows

By Geoffrey Mohan, Los Angeles Times (TNS)

The frozen fringes of western Antarctica have been melting 70 percent faster in the last decade, raising concern that an important buttress keeping land-based ice sheets from flowing to the sea could collapse or vanish in coming decades, a new study shows.

An acceleration in the flow of massive ice sheets would add substantially to the ongoing rise of sea levels, according to Fernando Paolo, a geophysicist at the University of California, San Diego’s Scripps Institution of Oceanography and lead author of the study published online Thursday in the journal Science.

“They hold back the ice discharge from the ice sheet into the ocean,” Paolo said. “In the long term, that is the main concern from losing volume from an ice shelf.”

The study adds to growing concern that climate change has altered the equilibrium of growth and melt on a part of the continent holding an estimated 530,000 cubic miles of ice. That’s enough ice to raise the sea level by 11 feet, by some estimates.

“If the rate of change that we have observed remains the same, then we should expect a larger contribution of the ice sheet to sea level rise,” Paolo said.

Shelves in the Bellingshausen and Amundsen seas had the most rapid thinning, losing an average of 24 to 63 feet per decade, according to the study, which analyzed satellite-based radar data from 1994-2012.

The most dramatic loss occurred on the Venable ice shelf on the Bellingshausen Sea, which thinned by an average of 118 feet per decade, according to the study. At that rate, it could disappear in 100 years. The same fate could befall the Crosson shelf on the Amundsen Sea, the study found.

Those rates are conservative “lower bound” estimates, said Paolo.

On the eastern side of Antarctica, previous ice sheet growth has ground to a halt over the last decade, the study showed.

The mechanics behind the changes in the east and west of Antarctica, however, are different, largely because the geology of each is distinct.

Glaciers form from the long-term accumulation of snowfall that compresses and flows slowly downhill toward the sea. In the east, these ice masses are predominantly anchored to land, so growth and decline are driven largely by changes in snowfall. Those glaciers nonetheless have tongue-like extensions floating on the sea, and studies have shown these shelves are thinning as rapidly as those in the west.

In the west, most of the ice sheet already is floating on the sea and is “grounded” to the continent below sea level. Warmer waters coming into contact with that boundary, or grounding line, are thinning it from the bottom, causing more of the sheet to become buoyant. That effectively causes this grounding line to migrate inward, potentially for many miles.

Such a retreat is particularly dangerous in the many areas of western Antarctica that have a retrograde shoreline — where the inland slope is downward. The retreat of the grounding line in those areas could trigger runaway acceleration of land glaciers, according to the study.

“After we pass that tipping point, the ice sheet just keeps flowing” regardless of the ocean water’s influence, Paolo said.

The forces driving both trends point toward altered wind patterns over Antarctica that bring less precipitation to east Antarctica and warmer water to the continent’s ice shelves. That, in turn, is likely caused by long-term changes in climate linked to the warming effect of increased carbon building up in Earth’s atmosphere, Paolo said.

By clustering the data in three-month snapshots over 18-mile swaths, the researchers were able to offer a high-resolution view of many individual shelves and differentiate short-term, local fluctuations from longer climate-related trends. Several earlier studies looked at shorter intervals over much broader regions, the authors noted.

The more detailed mosaic presented by the new study nonetheless offered little to surprise Eric Rignot, a glaciologist at UC Irvine and NASA’s Jet Propulsion Laboratory in La Canada-Flintridge, California.

His research, which analyzed 40 years of data, suggests that many glaciers already have reached a point of no return.

“It does emphasize that a number of ice shelves are not healthy, which is bad news for the glaciers that flow into them because the glaciers will start flowing faster and raise sea level faster,” Rignot said.

Photo: NASA Goddard Space Flight Center via Flickr

Archaeologists Rush To Save Yup’ik Treasures Threatened By Vanishing Shoreline

Archaeologists Rush To Save Yup’ik Treasures Threatened By Vanishing Shoreline

By Lisa Demer, Alaska Dispatch News

QUINHAGAK, Alaska — On the eroding Bering Sea coast of far Western Alaska, archaeologists from around the world are unearthing remnants of an ancient Yup’ik village frozen in place for hundreds of years.

Archaeologists involved say it’s the biggest excavation of Yup’ik artifacts from before the arrival of Russians and other Europeans in the early 1800s. The research is taking place in this remote Yukon-Kuskokwim Delta village as well as labs in Europe, Canada, and the United States.

In a region where tradition says old treasures should remain undisturbed, the Yup’ik people of Quinhagak invited the archaeologists in.

Why? “Because we had nothing,” said Warren Jones, president of the village corporation, Qanirtuuq Inc., which owns the dig site land. Cultural elements, including language and traditional dance, were stifled by the Moravian missionaries and nearly lost, said Jones, a behind-the-scenes leader in Quinhagak, home to about 700 people on Kuskokwim Bay some 70 miles southwest of Bethel.

Growing up “all I heard about was the church stuff, not what our ancestors did,” he said. They had stories but not ancient harpoons, stone ulus or little figurines of mythical creatures.

In a project that began five years ago, scholars, students, and Quinhagak residents are working together to carefully dismantle, document, and save relics from a sod house site they call “Nunalleq,” or old village.

“This is the first excavation of a Yup’ik house,” said lead archaeologist Rick Knecht, who has worked in Alaska since 1983 and now is with the University of Aberdeen in Scotland. “It’s not just any house. It’s a pretty spectacular one.”

Carbon dating of grasses and berry seeds at the site provides evidence that people first lived there in the 1300s, Knecht said. Then the village was attacked and set ablaze around 1640 by a neighboring settlement during the region’s “Bow and Arrow Wars,” he said. On the other side of the continent, the Pilgrims had just arrived in New England. But here, people were killed. The site was abandoned.

The old sod houses are on the Bering Sea coast a few miles across the tundra from Quinhagak. They collapsed in the fire and over time. The site was hidden in the tall grasses.

At the center, archaeologists say they found a traditional large men’s winter house. Smaller rooms connected by covered wooden walkways were added over the years, maybe as a way to bring in and protect women and children during the village wars, the researchers say. Traditionally, women and children lived separately from the men.

Until the permafrost began melting and the edge of the tundra eroded into the sea, the old village site, down to wooden cooking spoons, was well-preserved in the hard-frozen earth.

“There are all sorts of ghastly consequences to global warming but the one we’re worried about is the loss of cultural heritage,” Knecht said. “Because people live on these coastlines and the archaeological record is here.”

Just in the past five years, 30 feet at the edge of the dig site has been lost.

“It’s really going fast, right in front of our eyes,” Knecht said. Had the work not started when it did in 2009, thousands of artifacts at this one site would have washed away.

Quinhagak likely was one of dozens of settlements, maybe more, in the Yukon-Kuskokwim Delta at the time, and may have been sizable, said Ann Fienup-Riordan, an Alaska-based cultural anthropologist who has worked with Yup’ik people for 40 years. The people here probably lived semi-nomadically out of necessity, traveling to the food sources by season. The old village may have been a longtime winter home. But much is unknown.

“The Y-K region is the black hole of archaeology in the state of Alaska. There is so little work out there,” Fienup-Riordan said. By the time the Russians came, around 1830, about 15,000 people lived in the Yukon-Kuskokwim Delta, she said. The region now has about 25,000.

Archaeologists are concentrating on the men’s house as a rare opportunity to find and record items still in place.

“We have this kind of instant in time where the house was abandoned because of a disaster, because it burnt down,” said Charlotta Hillerdal, who is also with the University of Aberdeen and is one of Knecht’s co-investigators in the dig. “We have kind of captured everything in the house at its latest phase.”

The diggers have collected close to 50,000 items, counting ancient animal bones, bits of grass mats that covered the walls, and fragments of wooden tools. Of those, as many as 5,000 are special enough to display in a museum, Knecht said. Jones’ favorite: a mask with a dual wolf-human face, a symbol of transformation. All of it is evidence of human activity, Knecht said.

The work has attracted experts in many specialties: pottery and ulus, plants and bugs, dolls and shamans, bones and baskets. Diggers this year came from Canada, Scotland, Australia, Portugal, Sweden, France, Lithuania, and the United States.

Veronique Forbes, the program’s assistant field director and an archaeo-entomologist from Quebec whom everyone calls “the bug lady,” is studying insects inside and outside the sod house.

“The most interesting thing is that you can literally use insects to reconstruct activities inside the houses,” Forbes said. She’s finding dog lice, human lice, fleas, and surprising numbers of a particular kind of beetle that does not seem prevalent in the tundra now based on what she caught in little bug traps. The large numbers of dog lice tell her the people processed animal skins inside.

Fienup-Riordan, the anthropologist, collected impressions and stories from Quinhagak elders about the objects found. Team members brought in trays of dolls, hunting tools, woven pieces, and more for elders, who talked in Yup’ik, sometimes very enthusiastically, about the finds. One elder, George Pleasant, was able to identity the source of the stone for an ulu blade by its color. He described some wooden pieces not as handles, as the archaeologists guessed, but as weights for fishing nets.

“I think it’s the best thing anybody came and helped us do,” elder Annie Cleveland said of the dig.

The artifacts confirm and add detail to the stories of the village, Knecht said. Fienup-Riordan now has a date for the massacre story. What the elders say adds layers of explanation.

“We only get one shot at it,” Knecht said. “These are all pages in the Yup’ik history book.”

Village corporation leaders in consultation with elders are partners with the scientists in decision-making: when to dig, how to preserve the site, what to do with the finds. When archaeologists discovered bodies of several people killed in that long-ago raid, they consulted with village leaders and reburied the bodies.

Recently, the archaeologists put the year’s most interesting recovered objects on display in the big red community building and invited the whole village to see — and touch — them. A tiny seal amulet made of mammoth ivory. Wooden masks that had been broken in half. Stone harpoon tips. Pieces of model kayaks that show the evolution of the design. Researchers encouraged children to moisten the old wooden items with paintbrushes dipped in water.

“Be really gentle,” Ella McDonagh, a University of Aberdeen student from Scotland, told one group. “Fantastic! Well done! You are a pro at this!”

At a table with tiny pieces of carved ivory jewelry, John Smith, a village master carver, marveled at the skill of his ancestors before they had electric tools and metal blades. It inspired him to recreate some of the more intricate designs but he’s not yet satisfied with the result. He’ll keep at it. Maybe the dig project will draw village kids away from their video games and cellphones, he said.

Artifacts are shipped each year to the University of Aberdeen, which has a northern archaeology program and built a lab to process the Alaska collection.

By 2017, the researchers say, some artifacts will come home to Alaska and the Yukon-Kuskokwim Delta.

Both the archaeologists and residents of Quinhagak say they want to create a village cultural center to display some of the ancient tools and art, and provide a place for artists and craftsmen to work and teach others. The Association of Village Council Presidents may create a repository in Bethel.

Quinhagak may just be the start, Knecht said. Other ancient Alaska village sites along the coast and on rivers are eroding too.

Their stories have yet to be uncovered.

Photo: Anchorage Daily News/MCT/Erik Hill

Interested in national news? Sign up for our daily email newsletter!