A groundbreaking study published in the journal Science on July 20 has shed light on Greenland’s climate history, indicating that most of the country experienced a major meltdown approximately 400,000 years ago. This new evidence suggests that Greenland may be more susceptible to climate change than previously believed.
Researchers from various institutions worldwide collaborated on the study, utilizing decades-old sediment collected during a covert U.S. military operation known as Project Iceworm, conducted during the Cold War era. The samples were gathered from beneath thousands of feet of ice at a military base named Camp Century, which was purportedly an Arctic science station. In reality, the base was an attempt to conceal nuclear missiles beneath Greenland’s ice, in close proximity to the Soviet Union.
The well-preserved sediment cores, containing vegetation such as leaves and moss, revealed that Greenland was largely ice-free during a period called Marine Isotope Stage 11, approximately 416,000 years ago, give or take 38,000 years. This finding contradicts the assumption that Greenland’s ice sheet had been relatively stable for around 2.5 million years. Instead, the study provides “bulletproof evidence” that significant portions of the ice sheet melted during past periods of warming.
By analyzing the sediment for luminescence signals, the scientists determined the last time it was exposed to sunlight. Additionally, they studied quartz from the sediment, which contained rare isotopes of beryllium and aluminum, indicating recent exposure to the sun. Their findings indicate that the sediment had been ice-free less than 14,000 years before being buried under ice again.
Understanding Greenland’s climatic history is crucial in predicting the rate of ice sheet melting in response to present-day climate changes. The study warns that with a melting Greenland contributing around 23 feet to rising sea levels, coastal cities worldwide face significant risks. To combat such consequences, the researchers emphasize the urgent need to reduce carbon dioxide concentrations in the atmosphere. Otherwise, the study suggests a “warm, wet, and largely ice-free future for planet Earth.”