Deep under Greenland’s ice, a thin layer of frozen dirt and rock has been holding a secret for thousands of years. Now, a drilling project co-led by the University at Buffalo has brought that secret to the surface, and it carries a sharp warning. The first study from GreenDrill reports that a high point of Greenland’s ice sheet, the Prudhoe Dome ice cap in the northwest, disappeared completely about 7,000 years ago. Scientists did not expect the melt to be so recent. That timing matters because it happened during the Holocene, an interglacial period that began about 11,000 years ago and continues today. Many people think of the Holocene as steady and calm. It is also when humans began farming and building early societies. Yet the study suggests that even modest natural warmth in that era pushed a key section of the ice sheet beyond a tipping point. Maps of study area. (CREDIT: Nature Geoscience) “This is a time known for climate stability, when humans first began developing farming practices and taking steps toward civilization,” …