Scientists from the Oregon State University conducted chemical analyses on air bubbles trapped within the West Antarctic Ice Sheet Divide ice core. To do this, the research team tapped into bubbles of air trapped in West Antarctic Ice Sheet Divide ice core that essentially preserved the delicate balance of gasses present in Earth’s atmosphere at the time of their icy entombment. The team had to drill some 2 miles deep to get enough ice to study a 50,000 year time span. Named after German marine geologist Hartmut Heinrich, these events coincide with a cold spell in the North Atlantic caused by icebergs breaking off from the Laurentide Ice Sheet. “We think [Heinrich events] are caused by a dramatic collapse of the North American ice sheet,” OSU’s Christo Buizert, a co-author on the study, said in a press statement.