Approximately half of the ice-mass loss currently occurring in Greenland is the result of dynamic processes leading to the export of calf ice from the Greenland Ice Sheet's marine margins. Rapid changes in glacier flow speeds, thinning rates, and terminus positions have been observed during the past decade, but remain poorly understood. Many of Greenland's largest glaciers also produce seismic signals equivalent in amplitude to those from earthquakes of magnitude ~ 5. The earthquakes show a strong seasonal signal, with most events occurring in late summer, as well as a secular variation, with 3-6 times as many earthquakes occurring in each recent year as in the early 1990s. We combine observations of globally recorded seismic signals with local geodetic observations at a large Greenland outlet glacier to obtain insight into the glacial-earthquake source process and the response of outlet glaciers to changing environmental conditions, including ice loss at the terminus and varying surface meltwater input. Systematic analysis of glacial earthquakes across Greenland shows that spatio-temporal trends in earthquake occurrence are closely linked to changes in ice dynamics, and allows us to use the earthquakes as a remote-sensing tool.