Rignot used radar data taken between 1992 and
1996 by two European satellites,
ERS-1 and
ERS-2,
to generate interference patterns that are sensitive to small vertical movements.
These patterns provide information on the
velocity of the
ice - how fast it is creeping towards the
bay - and
the
hinge point - the
position on the
glacier at which ice moves from resting on the
bay bed to ice floating on the
water.
Recent measurements have suggested that the
Pine Island
glacier is melting at a much faster rate than other large ice shelves in the
Antarctic.
Researchers believed this was being caused by an influx of warm water from the
Southern Pacific Ocean. Rignot's latest work concludes that 76 ± 2 km3 of ice is being discharged into the bay each year,
while only 71 ± 7 km3 is replenished from the Antarctic interior - which indicates that the glacier is shrinking at a startling rate. If this data does herald the start of collapse for the Antarctic ice sheet,
water levels could rise by more than 5 m within a couple of centuries.
Antarctic glaciers feel the heat
Jul 24, 1998
The Pine Island Glacier in West Antarctica is shrinking at a startling rate according to satellite observations. And the "hinge-point" of the glacier is retreating at 1.2 km per year according to Eric Rignot of the Jet Propulsion Laboratory in California. Geophysicists believe that the glacier is theoretically unstable and that the retreat could become irreversible. Many believe that such an event would be strong evidence for climatic change. Rignot cautions that the retreat he has observed might be a short-lived phenomenon, but adds it could still have implications for the stability of ice-sheets along the entire Antarctic coastline (Science 281 549).





