How do we know Greenland is getting lower?

Research note · surface elevation and ice-sheet change

Satellite measurements can detect changes in the height of the Greenland ice sheet, but a lower surface does not always translate directly into the same amount of ice loss. Snowfall, melting, compaction and seasonal change can all affect the measured elevation.

Rendering Figure 3…
Comparing surface height change with estimated ice loss
Jason Box

THE BOXMAN RETURNS

A longitudinal study in cryospheric vigilance failure.

Figure 3. The apparent re-emergence of a familiar glaciological signal following an extended period of observational silence.