Greenland’s Greener History

 

With global warming comes worries about the potential collapse of Earth’s remaining glaciers, including the second largest body of ice on our planet -- the Greenland ice sheet. Dr. Tammy Rittenour’s luminescence analysis of samples collected from the ground surface deep underneath Greenland’s ice sheet reveals the Arctic island was indeed a green land, as recently as 416,000 years ago. “We’re discovering the ice sheet is much more sensitive to climate change than we previously thought,” says Dr. Rittenour.

Rittenour and colleagues from the University of Vermont and 14 other institutions, reported findings of their NSF funded research this past year in the journal Science. “We had always assumed the ice sheet has remained about the same for nearly 2.5 million years,” says Rittenour, “but our investigation indicates it melted enough to allow the growth of moss, shrubs and buzzing insects during an interglacial period called Marine Isotope Stage 11, between 424,000 to 374,000 years ago.”

The team’s analysis is possible due to samples collected from an extraordinary and nearly forgotten archive -- frozen soil samples from the base of an ice core collected at Camp Century (a secret, cold-war military base in Greenland). The core spent more than 60 years in a freezer until recently rediscovered.

“We have very few samples from below the Greenland ice sheet, because most drilling missions stop when they reach the base of the ice,” Rittenour says. “These rediscovered Camp Century sediments represent a unique, unspoiled time capsule of past conditions. If we can lose the far northwest portion of the Greenland ice sheet under natural conditions, then we’re treading dangerous waters given current elevated greenhouse gas conditions.”