This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The site of a former U.S. military base in Greenland was ice-free at a time when summers were a few degrees warmer than today, according to a new University at Buffalo–led study of ancient sediment recovered from beneath the site in the 1960s. Researchers found that summer temperatures at Camp Century—where the U.S.
Army pursued a secret Cold War plan to hide nuclear missiles beneath the ice—were 4.7 degrees Celsius (8.5 degrees Fahrenheit) warmer than modern summers during an ice-free period approximately 416,000 years ago. For the site to have been ice-free, the Greenland Ice Sheet would have had to retreat more than 60 miles (97 kilometers) from its present-day edge in that region. "It's striking that a period of moderately warmer temperatures coincided with such a substantial retreat of the ice sheet," says the study's first author, John Michael Aguilar, a postdoctoral fellow at the UB RENEW Institute.
Published Sept. 28 in Climate of the Past, the findings come as scientists project substantial warming across the Arctic in the coming decades. Average annual Arctic temperatures could rise anywhere from 3.3 to 10 degrees Celsius by the end of the century, depending on emissions, according to the Intergovernmental Panel on Climate Change (IPCC). "This work gives us a better understanding of how the ice sheet responds to sustained warming and what may be possible in the future," says corresponding author Elizabeth Thomas, Ph.D., associate professor in the Department of Earth Sciences in the UB College of Arts and Sciences.
Pulled up from nearly a mile (1.6 kilometers) beneath the ice sheet during the failed Project Iceworm, the sediment has provided Thomas and her collaborators with important clues about the ancient climate at Camp Century. That includes the evidence that the area was ice-free approximately 416,000 years ago, when the sediment was last exposed to sunlight. This new study marks the first time the researchers have used the sediment to reconstruct summer temperatures at Camp Century during the ice-free period.
In fact, they believe it is the first quantitative estimate of land-based summer temperatures anywhere in Greenland during this ancient warm period. Such estimates have been difficult to obtain because advancing ice sheets subsequently eroded most sediment from that time. They were able to reconstruct the temperatures by analyzing fatty molecules produced by bacteria and preserved in the sediment.
"The types and proportions of these molecules change depending on the temperature," Aguilar says. "By comparing them with similar molecules found in modern Arctic lakes, we were able to estimate how warm it was at Camp Century." Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. d research that matter—daily or weekly. The researchers were somewhat surprised at the results.
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