Preglacial landscape found deep under Greenland ice

Preglacial landscape found deep under Greenland ice

by Staff Writers
Washington (AFP) April 18, 2014

US geologists said Thursday they have uncovered a preglacial tundra landscape preserved for 2.7 million years far below the Greenland ice sheet.
Glaciers are known to scrape everything off any given plot of land -- vegetation, soil and even the top layer of bedrock -- so scientists expressed great surprise that they had found the landscape in pristine condition below two miles (three kilometers) of ice.
The finding provides strong evidence that the ice sheet has existed for much longer than previously known, and survived numerous global warming episodes, according to the lead researcher, University of Vermont geologist Paul Bierman.
Rather than scraping and sculpting the landscape, the ice sheet has been frozen to the ground, effectively creating "a refrigerator that's preserved this antique landscape," Bierman said.
The finding suggests that even during the warmest periods of the ice sheet's life, the center of Greenland was stable and did not fully melt, allowing the tundra landscape to be sealed without modification through millions of years of changing temperatures.

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Massive canyon discovered buried under Greenland ice

Scientists uncover vast gorge stretching at least 466 miles believed to be millions of years old

• Press Association
• theguardian.com, Friday 30 August 2013 11.17 EDT

A vast gorge in the Earth on the same scale as the Grand Canyon lies buried under ice in Greenland, scientists have learned.
The massive hidden canyon is at least 466 miles (740km) long and up to 800 metres (2,600ft) deep in places.
The feature, resembling a meandering river channel, is believed to pre-date the ice sheet that has covered Greenland for millions of years.

3D visualisation of the canyon under Greenland's ice sheet. Photograph: Professor Jonathan Bamber

Prof Jonathan Bamber, from the school of geographical studies at the University of Bristol, said: "With Google Streetview available for many cities around the world and digital maps for everything from population density to happiness, one might assume that the landscape of the Earth has been fully explored and mapped.
"Our research shows there's still a lot left to discover."
The canyon was uncovered by airborne radar which can penetrate ice and bounce off the land beneath.
Scientists pieced together radar measurements covering thousands of kilometres collected by Arctic researchers over several decades. They found evidence of a fissure in the bedrock stretching northwards almost from the centre of Greenland.
The canyon ends in a deep fjord connecting it to the Arctic ocean.

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the journal Cryosphere finds that Jakobshavn's averaged annual speed in 2012 and 2013 was nearly three times its rate in the 1990s

 

Greenland glacier hits record speed

By Paul Rincon Science editor, BBC News website

Jakobshavn is located at the eastern end of the Ilulissat Icefjord (seen here), Greenland

In summer, the Jakobshavn Glacier - widely thought to have spawned the iceberg that sank the Titanic - is moving about four times faster than it was in the 1990s.
The Greenland Ice Sheet has seen record melting in recent years and would raise sea levels 6m were it all to vanish.
Details of the research are published in The Cryosphere journal.
Ian Joughin and Ben Smith of the University of Washington's Polar Science Center in Seattle analysed pictures from the German TerraSAR-X satellites to measure the speed of the glacier.
"As the glacier moves we can track changes between images to produce maps of the ice flow velocity," said Dr Joughin, the study's lead author.
In the summer of 2012, the glacier reached a record speed of more than 17km per year - more than 46m per day.
"We are now seeing summer speeds more than four times what they were in the 1990s on a glacier which at that time was believed to be one of the fastest, if not the fastest, glacier in Greenland," Ian Joughin explained.

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National Geographic

Greenland Glacier Races to Ocean at Record Speed

Jakobshavn, the glacier widely thought to have spawned the iceberg that sank the Titanic, reaches record speeds.

Chunks of ice litter the ocean in front of Greenland's Jakobshavn glacier.

PHOTOGRAPH BY PAUL SOUDERS

Jane J. Lee

National Geographic

Published February 4, 2014

A Greenland glacier named Jakobshavn Isbrae, which many believe spawned the iceberg that sank the Titanic, has hit record speeds in its race to the ocean. Some may be tempted to call it the king of the glacier world, but this speedy river of ice is nothing to crow about.

A new study published February 3 in the journal Cryosphere finds that Jakobshavn's averaged annual speed in 2012 and 2013 was nearly three times its rate in the 1990s. Its flow rate during the summer months was even faster.

"We are now seeing summer speeds more than four times what they were in the 1990s on a glacier which at that time was believed to be one of the fastest, if not the fastest, glaciers in Greenland," Ian Joughin, a researcher at the University of Washington in Seattle, told the BBC.

In summer 2012, Jakobshavn reached speeds of about 150 feet (46 meters) per day.

Other glaciers may periodically flow faster than Jakobshavn, but Greenland's most well known glacier is the bellwether of climate change in the region and likely contributes more to sea-level rise than any other glacier in the Northern Hemisphere—as much as 4 percent of the global total, Joughin and his colleagues found in an earlier study. (Read about glacial meltdown in National Geographic magazine.)

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Massive Lake Found Under Greenland Ice

Water from the Greenland perennial firn aquifer draining from a core extracted 12 m below the surface of the ice sheet. The core was drilled in April, months prior to seasonal melt, with air temperatures -15 C confirming the water was retained at depth th

VOAnews.com

December 23, 2013

A massive lake has been found under the ice in Greenland.  The 43,500 square kilometer body of water could have major implications for understanding sea level rise.
Researchers at the University of Utah say the lake, known as a “perennial firn aquifer,” remains liquid year-round despite the otherwise perpetually frozen landscape.
“Large amounts of snow fall on the surface late in the summer and quickly insulates the water from the subfreezing air temperatures above, allowing the water to persist all year long,” said Rick Forster, lead author and professor of geography at the University of Utah.
The Greenland Ice Sheet is vast, covering roughly the same area as the states of California, Nevada, Arizona, New Mexico, Colorado and Utah combined. The average thickness of the ice is 5,000 feet. In 2012, the ice sheet lost volume of 60 cubic miles – a record for melt and runoff.
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Greenland's Snow Hides 100 Billion Tons of Water

By Becky Oskin, Staff Writer   |   December 22, 2013 01:00pm ET

A drill rig was used to extract old snow (firn) cores from within the Greenland snow aquifer. Credit: Evan Burgess

 

Big surprises still hide beneath the frozen surface of snowy Greenland. Despite decades of poking and prodding by scientists, only now has the massive ice island revealed a hidden aquifer.
In southeast Greenland, more than 100 billion tons of liquid water soaks a slushy snow layer buried anywhere from 15 to 160 feet (5 to 50 meters) below the surface. This snow aquifer covers more than 27,000 square miles (70,000 square kilometers) — an area bigger than West Virginia — researchers report today (Dec. 22) in the journal Nature Geoscience.
"We thought we had an understanding of how things work in Greenland, but here is this entire storage system of water we didn't realize was there," said Richard Forster, lead study author and a glaciologist at the University of Utah.
The discovery will help scientists better understand the fate of Greenland's annual surface melt, which contributes to sea level rise. When the summer sun warms the Arctic island, a giant water world of stunning blue lakes and streams appears atop the ice. Tracking this surface runoff helps scientists account for ice lost to melting each year. Until now, researchers thought most of this water went to the ocean or refroze on the ice. Now they've found a new hiding place.
"This throws an additional complexity into the system," Forster told LiveScience.
There is enough water in the snow aquifer to raise global sea level by 0.015 inches (0.4 millimeters), according to a separate study by the same team published Nov. 30 in the journal Geophysical Research Letters (GRL). Every year, Greenland adds 0.03 inches (0.7 mm) of water to global sea level rise from melting snow and ice, Forster said. [Top 10 Surprising Results of Global Warming]
Where water flows
No one yet knows how old the water in the aquifer is, and whether it stays trapped in the snow or reaches the ocean in slow streams or catastrophic floods. However, the top of the water table rose after Greenland's huge surface melt in 2012, the researchers report in their GRL study.

Water from the Greenland snow aquifer draining from a drill core extracted 40 feet (12 meters) below the surface of the ice sheet in April, before the summer surface melt, with air temperatures of 5 degrees Fahrenheit (minus 15 degrees Celsius).
Credit: Ludovic Brucker

View full size image

The group will return to southeast Greenland in the coming years to answer these and other questions, Forster said. "Just seeing how old it is would answer a lot of questions," he said.
The final destination of Greenland's melt water is also key to understanding how the ice sheet ebbs and flows, because water under the ice sheet lubricates flowing glaciers. Researchers know some melt water goes to the bottom of the ice, trickling through cracks and racing through vertical pipes called moulins. Some of the water also simply refreezes on the surface when winter comes. Liquid water sitting in buried snow layers can also slowly warm and melt the ice sheet.
"The existence of this rather flavorless natural snow cone has many implications for the future of the ice sheet, some that may make the ice go away faster and others that help keep the ice a little longer," said Richard Alley, a glaciologist at Pennsylvania State University, who was not involved in the study. "We would like to understand these implications better so we can help reduce the uncertainties about future changes."
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