Currently, Greenland is mostly covered with ice, but in the past it has been confirmed that almost all of the ice has melted and moss and plants have grown. This suggests that Greenland may be more vulnerable to global warming than expected. Courtesy of Joshua Brown/University of Vermont
The glaciers that cover Greenland, the largest island on the planet, are considered an indicator of climate change. This is because the sea level rises when polar glaciers, including Greenland, melt due to global warming.
Last year’s international academic journal’Nature Communications’ reported that Greenland’s glaciers have melted an average of 255 billion tons (tons) per year since 2003, and last year, 532 billion tons have melted, more than twice the average. When the entire Greenland melts, sea level is projected to rise by 6m.
A research team led by Paul Beerman, a professor at the Department of Geology at the University of Vermont, said in an international journal’PNAS’ on the 15th that the ice covering Greenland has melted at least once in the past 1 million years. Warned that the ice could melt much easier than expected.
The research team came to this conclusion by examining a mass of sediment excavated under an ice sheet of about 1.4 km (4560 ft) in Greenland.
This sediment is actually a product of the Cold War. In 1966, the U.S. military pursued the “Iceworm Project,” a military base called “Camp Century,” with the aim of hiding 600 nuclear missiles in the Arctic Circle, geographically close to the former Soviet Union, and in Greenland. Externally, Camp Century was paved as a scientific base for polar research.
The project failed, but scientists from the Army of Camp Century drilled ice cores in Greenland’s glaciers. These cores were once moved from the U.S. Army freezer to the U.S. Buffalo in the 1970s. It was then moved to a freezer in Copenhagen, Denmark in the 1990s, and then returned to the University of Vermont in 2017. What they got in their hands was a core sample drilled 120 km off the northwest coast of Greenland.
An ice core in Greenland was drilled at the US military base’Camp Century’ in the 1960s. Provided by the University of Vermont
The first author of the paper, Andrew Christ, a postdoctoral fellow at the Gunt Environmental Research Institute at the University of Vermont, saw an incredible sight while observing the sediments of the ice core under a microscope in 2019. Instead of sand and rocks, branches and leaves were mixed in the sediment. “What we found is a delicate plant structure that has been perfectly preserved,” he said. “It’s a time capsule that shows what kind of creatures lived in Greenland in the past.”
The team investigated the isotope ratio of aluminum and beryllium in the sediment. These are created by reacting with spacecraft flying from space when the soil is not covered with ice and exposed to the outside. They also investigated oxygen isotopes found only in ice to confirm that Greenland was covered with ice sheets at the time.
As a result, the research team concluded that most, if not all, of Greenland’s ice had melted once in the past million years, and that moss, spruce, and fir trees made Greenland green. The current glaciers were created by freezing again later. Christ’s postdoctoral researcher said, “This study means that Greenland may be more vulnerable to global warming than expected.”
“Greenland feels like a very remote island, but it can melt very quickly,” said Professor Beerman. “If Greenland melts (the sea level rises), New York and Miami will be submerged.”