Print article At first, Andrew Christ was ecstatic. In soil taken from the bottom of the Greenland ice sheet, he’d discovered the remains of ancient plants. Only one other team of researchers had ever found greenery beneath the mile-high ice mass. But then Christ determined how long it had been since that soil had seen sunlight: Less than a million years. Just a blink of an eye in geologic terms. And it dawned on him. If plants once grew at multiple spots on the surface of Greenland, that meant the ice that now covers the island had entirely melted. And if the whole Greenland ice sheet had melted once in the not-so-distant past, that meant it could go again.