On Thin Ice

By Charlotte Hsu

The Greenland Ice Sheet is the second-largest block of ice on Earth. And according to UB geophysicist Beata Csatho, we may be underestimating how fast it will shrink. In a recent study, she and colleagues analyzed massive amounts of NASA data to provide the world with its first comprehensive picture of how the ice sheet is changing—and feeding rising seas. The results are sobering.

Greenland Ice Sheet

This visualization depicts how the Greenland Ice Sheet changed from 2003-12. A close analysis reveals how little we understand about this shifting icescape—in particular, how it will respond to climate change.

Flawed Forecasts:

Until now, scientists have projected how all of Greenland would lose ice by extrapolating from the activity of just four large glaciers [labeled on map]. Csatho’s research shows that this analysis is not adequate: Changes at these four locations do not reflect what’s happening across the whole ice sheet.

A Complicated Puzzle:

An area this size houses 38 large glaciers that flow into the sea. In all, Greenland has 242 of these tongues of ice, and the study finds that they undergo complex patterns of thinning and thickening that current climate models fail to address.

Bad News in the Southeast:

Csatho’s team identified areas of rapid shrinkage in this region that current climate models miss. It’s one of several clues that indicate to Csatho that Greenland will shed ice more rapidly in the near future than previously thought.

A Massive Undertaking:

The study used data from NASA satellite and aerial survey missions (see Laser Precision) to reconstruct how the ice sheet’s elevation changed at 100,000 locations from 1993 to 2012.

Gray Lines:  Paths traveled by NASA’s ICESat satellite to collect data
Purple Lines:
  Paths traveled by NASA’s Operation IceBridge research aircrafts

NASA's Goddard Space Flight Center Scientific Visualization Studio

Photo: NASA's Goddard Space Flight Center Scientific Visualization Studio

Laser Precision:

Michael Gelen, JD ’88

NASA research vehicles used laser altimetry to measure the ice sheet’s elevation:

Step 1:  A plane (or satellite) fires a laser pulse.
Step 2:  The light hits a surface and is reflected back toward its source.
Step 3:  By measuring how long it takes for the laser pulse to reach the surface and return, scientists can calculate the elevation of the surface to an accuracy within centimeters.