The Vital Contributions of Geodesy to our Understanding of the Ice Sheets of Antarctica and Greenland

Abstract:

The ice sheets of Antarctica and Greenland contain enough ice to raise global sea-level by more than 60 m. Predicting their future behaviour requires understanding their dynamics and state of balance, and geodetic techniques have provided information on these properties, on various time scales. Here, we give an overview of the major contributions of geodetic techniques to ice-sheet research over the past several decades. Early leveling measurements made in the 1960’s provided estimates of ice velocity (from the horizontal component) and height (from the vertical component) in a few regions, and this coverage has expanded since the 1980s through more routine GPS surveys. Time series of velocity changes inform about the local dynamics of an ice-sheet region, and time series of height measurements inform about both the mass balance and glacial isostatic rebound. Since the early 1990s, increased coverage of height measurements is obtained using satellite-derived height estimates from radar and laser altimetry, and for velocity measurements from SAR. Gravity measurements from GRACE since 2002 have provided independent way of monitoring ice sheet mass. Together these various techniques have transformed our understanding of the ice sheets and taught us about variability on short and long time scales, which is allowing us to identify the processes driving these changes.