The snow-free landscape of Allan Hills has been a scientific destination for decades. Explorers have made the hour-long plane ride from McMurdo Station, the primary base of U.S. operations in Antarctica, to look for evidence of prehistoric and extraterrestrial remains in the form of dinosaur bones and meteorites.
Paleoclimate scientist Andrei Kurbatov comes for some of the oldest ice on the planet. There are indications that it could be more than 2.5 million years old. And near the surface.
For Kurbatov, the blue ice here is gold.
“The maximum achievement is to find the oldest ice and demonstrate its suitability for reconstructing quality environmental records beyond what we currently get in ice core records,” says Kurbatov, an assistant research professor with the University of Maine Climate Change Institute, who heads a four-year, $460,000 National Science Foundation, Office of Polar Programs collaborative research project called 2MBIA to explore the ice archive at Allan Hills.
“Our goal is to collect records not reachable by existing ice cores,” he says.
What’s particularly important at Allan Hills is that massive ice flow has been obstructed by subsurface terrain, pushing ice to the surface. Snow is swept away by wind or vaporized in a process called sublimation. What’s revealed is old blue ice that came from miles away.
The fact that such old ice layers are accessible on and near the surface means that trenching and surface sampling rather than coring techniques could be used. Like ice taken in cores from around the globe by UMaine Climate Change Director Paul Mayewski, a co-investigator on the 2MBIA project, the Allan Hills samples will be analyzed for ice chemistry, particles and stable isotopes of water to reconstruct details of past climate change.
A unique part of the analysis is the dating of the old air trapped in the ice. Princeton University geoscientist Michael Bender, also a 2MBIA investigator, has developed new methods for dating such trapped gas bubbles in old glacial ice using argon isotopes.
Collaborators on the project are Kuni Nishiizumi from the University of California – Berkeley, who will help date meteorite fragments found in the area to correlate with the ages of the ice, and Vandy Spikes from the Earth Science Agency, a consulting group in Nevada.
Spikes was one of the first to speculate that the Allan Hills Ice Field yielded ancient ice at its surface. He was introduced to the Allan Hills Blue Ice Area when he was a student at Ohio State, and revisited it as a UMaine graduate student researcher.
He confirmed that the ice flow in the Allan Hills area is very slow and correlated the ages of meteorites with the age of the ice.
For years, scientists have collected pieces of meteorites from this area, where the extraterrestrial materials get buried on impact but are later exposed, unlike other places on Earth. Some meteorite fragments are as much as 2.8 million years old, giving scientists like Kurbatov hope that the ice has a similar vintage.
Last November and December, Kurbatov’s research team completed its first field season at Allan Hills, taking ice samples from a 3-mile by 6-mile area on the single, massive flow. A second field season will be this November through January.
The old ice has the potential to extend the deep ice core records, which now stand at 800,000 years. The project’s long-term goal is to establish an “international climate park” at Allan Hills, where scientists from around the globe can sample large quantities of ice of known ages.
“This has implications for climate research, expanding our understanding of global cycles,” says Kurbatov.
Image Description: The Allan Hills Ice Field contains some of the most ancient ice on the planet.