Sustained high winter glacier velocities from brief warm events
AbstractGlacier winter velocities are generally slower than summer velocities,
that increase early in the season when meltwater runoff reaches the bed.
Velocities generally decrease later in the season as the subglacial
system becomes channelized. With an innovative ice cave monitoring
technique, here we show that a single week-long warm event in the winter
triggers an internal drainage system flooding event, leading to velocity
doubling for the remainder of the winter, unlike summer speedups when
additional meltwater forms efficient drainage channels that reduce
glacier velocity. As the climate warms and surface melt and rain events
increase during winter months, sustained high winter glacier velocities
are likely to occur more often. Increasing glacier velocity near the
terminus leads to additional ice entering the fjord, and an increase of
sea level rise contribution during these sustained season-long events.