About 400,000 years ago, large parts of Greenland were ice-free. Scrubby tundra basked in the Sun’s rays on the island’s northwest highlands. A forest of spruce trees, buzzing with insects, covered the southern part of Greenland. Global sea level was much higher than 20 and 40 feet above today’s levels. Around the world, the land today is home to hundreds of millions of people underwater.
Scientists uncovered that when they studied, sediments extracted decades ago from beneath a mile-thick section of Greenland’s ice sheet as part of a secret U.S. military project during the Cold War. A new analysis of that once-forgotten ice core sample reveals that Greenland’s climate has changed before and could change again.
During the Camp Century project, researchers drilled through 4,560 feet of ice and then pulled out a 12-foot-long tube of sediment, a mix of soil and rock, from beneath the ice. The icy specimen was misplaced in a freezer for decades before being accidentally rediscovered in 2017. When scientists recently looked at the ice core’s contents, they were stunned to find that it contained not only leaves and moss but also traces of a forest that once grew on the surface of Greenland.
The ice core data revealed that Greenland was a green landscape about 416,000 years ago, plus or minus 38,000 years, according to an international team of scientists study published this week in Science. Previous research suggested that the ice sheet on Greenland has melted at least once in the last 1.1 million years, but until now, it was not clear exactly when.
In addition to its potential for future changes, the discovery of a once-forgotten Greenland ice core is helping scientists understand how rapidly the Arctic’s melting can occur. That is important because the current rate of Greenland’s melting is expected to significantly contribute to future global sea level rise, which will impact coastal communities.
Scientists are predicting that Greenland will continue to lose ice on average annually at a faster rate than previously believed. Whether that rapid melt is halted by global action to curb carbon emissions remains to be seen.