Bridging the Data Gap “IceBridge exists because we need to
understand how much ice the Greenland and Antarctic ice sheets
will contribute to sea level rise over the next couple of
decades,” says project scientist Michael Studinger. “In order to
do this, we need to measure how much the ice surface elevation
is changing from year to year.” The second major goal of
IceBridge, says Wagner, is to track how Arctic sea ice is
changing, which will help scientists understand its critical
role in climate and weather. Such measurements began three
decades ago with laser altimeters flown on airplanes, and then
expanded with the launch of ICESat in 2003. Its main instrument,
the Geoscience Laser Altimeter System, or GLAS, worked by
sending out short pulses (40 per second) of green and infrared
light. The light bounced off particles in the atmosphere or on
Earth’s surface and returned to a one-meter wide telescope. The
amount of light that returned, and the time it took to return,
depended on the height of the surface that