Recently, Greenland's three largest outlet glaciers have started moving faster, satellite data show.
Vatnajökull has around 30 outlet glaciers flowing from the ice cap.
In each case the major outlet glaciers accelerated by at least 50%, much larger than the impact noted due to summer meltwater increase.
Much larger icefalls may be found in the outlet glaciers of continental ice sheets.
A number of outlet glaciers reach down from Langjökull to the valleys and plains below.
Hoffellsjökull outlet glacier has cut through a central volcano which is named after Geitafell mountain.
The surface on the top of the plateau feeds many outlet glaciers, including the Engabreen glacier.
Hoffellsjökull is an outlet glacier which flows from the ice cap of Vatnajökull.
However, loss of mass on the Antarctic sheet may continue, if there is sufficient loss to outlet glaciers.
Glacier retreat has been observed in these outlet glaciers, resulting in an increase of the ice flow rate.