A new study of Greenland's rapidly melting ice sheets concludes, using a conservative model, that oceans will rise at least 10 inches over the coming years/decades. While no timeline was given, this melting will occur regardless of what humans do to curb greenhouse gas emissions. The reason is that the melting cycle has already been put into motion, and the combination of warming ocean temps, water from melted ice (that then melts more ice...sort of like pouring liquid water on ice cubes in a sink will melt the ice), and the fact that warming water expands in volume, means this rise is inevitable. Also, using sophisticated radar techniques, dozens of lakes below the surface ice have been discovered - this means there is melting happening underneath the ice that we had not observed before. Often some computer models were underestimating the rate of melting, and as further research is done more mechanisms for melting are being discovered to help us understand why the rates are quickening.
What's significant about Greenland's ice sheets is that they are land-based. They are not icebergs already in the water. If an iceberg melts, there won't be any rise. However, run-off water from land is new water in the ocean, and makes sea levels rise.