https://phys.org/news/2019-01-greenland-ice-faster.html

"Whatever this was, it couldn't be explained by glaciers, because there aren't many there," said Michael Bevis, lead author of the paper, Ohio Eminent Scholar and a professor of geodynamics at The Ohio State University. "It had to be the surface mass—the ice was melting inland from the coastline."

That melting, which Bevis and his co-authors believe is largely caused by global warming, means that in the southwestern part of Greenland, growing rivers of water are streaming into the ocean during summer. The key finding from their study: Southwest Greenland, which previously had not been considered a serious threat, will likely become a major future contributor to sea level rise.