"Somewhere between 1.5 and 2 degrees, there's a tipping point after which it will no longer be possible to maintain the Greenland Ice Sheet," Ruth Mottram, a climate scientist at the Danish Meteorological Institute, told Inside Climate News. "What we don't have a handle on is how quickly the Greenland Ice Sheet will be lost."
Greenland's ice is already approaching that tipping point, according to a study published in May. Whereas the melting that happened during warm cycles used to get balanced out when new ice formed during cool cycles, warm periods now cause significant meltdown and cool periods simply pause it.
That makes it difficult for the ice sheet to regenerate what it's losing.