Greenhouse gas emissions from human activities have already raised global average temperatures more than 1 degree Celsius (1.4 degrees Fahrenheit) since 1880. Greenland is losing ice at its fastest rate since humans invented agriculture, causing about 14 millimeters of sea level rise in the past half-century.
If the island’s entire ice sheet were to melt now, global sea levels would rise by more than 20 feet.
“We don’t want to see what that looks like,” said Christ, a geologist at the University of Vermont. “It underscores the urgency of needing to change the way things are going right now.”