A promising target in the quest for a 1-million-year-old Antarctic ice core

Related Articles

Related Articles

Ice cores offer a window into the history of Earth’s climate. Layers of ice reveal past temperatures, and gases trapped in bubbles reveal past atmospheric composition. The oldest continuous ice core so far comes from Dome C in East Antarctica and extends back 800,000 years.

But a tantalizing clue recently offered the possibility to go back even further. A collaborative study between the University of Washington and the University of Maine now pinpoints a location where an entire million years of undisturbed ice might be preserved intact.

“There’s a strong desire to push back the date of the oldest ice core record, to better understand what drives natural climate changes,” said Laura Kehrl, a UW doctoral student in Earth and space sciences and corresponding author of the recent paper in Geophysical Research Letters. “The Allan Hills has been an area of interest since the 1970s, when scientists started finding lunar and Martian meteorites that had struck Earth long ago. Now we’re discovering its potential for old ice.”

 

The team gathered observations in Antarctica’s Allan Hills Blue Ice Area, named for the blue ice that is exposed at the surface when ice above gets vaporized. This windy, desert area gets less than 1 centimetre of snow accumulation per year.

Allan Hills is located near the Trans-Antarctic Mountains, which separate the large, desert plateau of East Antarctica from the stormy West Antarctic Ice Sheet. Ice moves slowly here, less than 1 meter (3 feet) per year. The region had long been rejected in the search for an old ice core because ice flowing over the steep topography at the base seemed likely to be disturbed.

But surprising findings published last summer by a Princeton University team found fragments of ice as far back as 2.7 million years several hundred feet below the surface in the Allan Hills. Those isolated chunks had been separated from their full history. Now the UW team thinks it has found a location nearby that would have a continuous, unbroken record.

“A primary reason to seek such old ice is to understand one of the major puzzles of climate system history,” said second author Howard Conway, a UW research professor of Earth and space sciences and UW’s principal investigator of the project. The puzzle, he explained, is why Earth switched about 1 million years ago from having ice age cycles about every 41,000 years to every 100,000 years. Marine climate records show this switch occurred but they do not resolve details in the atmospheric composition 1 million years ago that might explain the cause.

During the austral summer of 2016, UW researchers travelled to McMurdo Station and then flew to the field site. With support from the National Science Foundation they set up a remote camp on a patch of snow in the Allan Hills, 6,400 feet above sea level.

Researchers used snow machines to tow ice-penetrating radar around the region. The radar sends radio waves into the ice, which reflect off of layers of ice with different chemistries and densities, providing an image of the structure below.

A computer model of glacier flow incorporating the data from those surveys suggests that million-year-old ice is about 25 to 35 meters (about 100 feet) above the bedrock at a site roughly 5 kilometers (3 miles) from the place where the 2.7-million-year-old ice was found.

The UW and Maine team has submitted a follow-up proposal to the National Science Foundation to drill the core. Kehrl says it’s “not unlikely” that they would retrieve an undisturbed record back to 1 million years. An added benefit of drilling here, she said, would be to learn the history of the Ross Ice Shelf and whether it has collapsed in the past, and how that corresponded to carbon dioxide levels in the atmosphere.

“Regardless of whether the million-year ice is there, the record is likely to be valuable,” Kehrl said.

UNIVERSITY OF WASHINGTON

Header Image – A snowstorm interrupted the fieldwork and left the researchers confined to their field camp for three days. In this windy desert region, most of the snow was blown away the next day. Credit: Laura Kehrl/University of Washington

Download the HeritageDaily mobile application on iOS and Android

More on this topic

LATEST NEWS

The Testimony of Trees: How Volcanic Eruptions Shaped 2000 Years of World History

Researchers have shown that over the past two thousand years, volcanoes have played a larger role in natural temperature variability than previously thought, and their climatic effects may have contributed to past societal and economic change.

Sentinels of Ocean Acidification Impacts Survived Earth’s Last Mass Extinction

Two groups of tiny, delicate marine organisms, sea butterflies and sea angels, were found to be surprisingly resilient--having survived dramatic global climate change and Earth's most recent mass extinction event 66 million years ago.

The Venerable Ensign Wasp, Killing Cockroaches For 25 million Years

An Oregon State University study has identified four new species of parasitic, cockroach-killing ensign wasps that became encased in tree resin 25 million years ago and were preserved as the resin fossilized into amber.

Modern Humans Reached Westernmost Europe 5,000 Years Earlier Than Previously Known

Modern humans arrived in the westernmost part of Europe 41,000 - 38,000 years ago, about 5,000 years earlier than previously known, according to Jonathan Haws, Ph.D., professor and chair of the Department of Anthropology at the University of Louisville, and an international team of researchers.

Akrotiri – The Ancient Town Buried by a Volcano

Akrotiri is an archaeological site and a Cycladic Bronze Age town, located on the Greek island of Santorini (Thera) near the present-day village of Akrotiri (for which the prehistoric site is named).

Château Gaillard – Richard the Lionheart’s Castle

Construction of the castle began in 1196 by King Richard I, also known as Richard the Lionheart - who ruled as King of England and held the Dukedom of Normandy, as well as several other territories.

Geoscientists Discovers Causes of Sudden Volcanic Eruptions

Tiny crystals, ten thousand times thinner than a human hair, can cause explosive volcanic eruptions.

Specimens From Ice Age Provide Clues to Origin of Pack-Hunting in Modern Wolves

Wolves today live and hunt in packs, which helps them take down large prey. But when did this group behavior evolve?

Popular stories

The Secret Hellfire Club and the Hellfire Caves

The Hellfire Club was an exclusive membership-based organisation for high-society rakes, that was first founded in London in 1718, by Philip, Duke of Wharton, and several of society's elites.

Port Royal – The Sodom of the New World

Port Royal, originally named Cagway was an English harbour town and base of operations for buccaneers and privateers (pirates) until the great earthquake of 1692.

Matthew Hopkins – The Real Witch-Hunter

Matthew Hopkins was an infamous witch-hunter during the 17th century, who published “The Discovery of Witches” in 1647, and whose witch-hunting methods were applied during the notorious Salem Witch Trials in colonial Massachusetts.

Did Corn Fuel Cahokia’s Rise?

A new study suggests that corn was the staple subsistence crop that allowed the pre-Columbian city of Cahokia to rise to prominence and flourish for nearly 300 years.