However, the models these measurements fed all assumed the ground under Greenland was rising, as it rebounds from the great mass of the ice sheets of the Last Glacial Maximum, at a similar global average.
It's not, according to a new study published Science Advances. The crust in an area on the southeast side of Greenland is rebouding up at 12 millimeters per year (compared to a handful of millimeters per year elsewhere on the island). This is probably because this part of Greenland's crust passed over a volcanic hotspot 40 million years ago (the same one now forming Iceland), which made that section of crust more pliable and prone to deformation by the weight of ice sheets.
This means that, if the land is rising faster than expected, more ice must be melting off than previously thought, or the Greenland ice cap would be bulging up in this spot, which it is not doing. Calculations by the study's authors estimate 200 more gigatons (10^7) of ice have been melting off Greenland each year, unaccounted for until now. That is 7% of Greenland's total ice loss.