Greenland's gigantic ice sheet is inching toward an irreversible tipping point, after which it will tumble into the ocean, a new study warns.
Just 3.6 degrees Fahrenheit (2 degrees Celsius) of further warming could be enough to trigger a collapse of the world's second-largest ice sheet, causing sea levels to rise by 23 feet (7 meters) and sowing havoc across global ecosystems.
