Complex pattern of Greenland Ice Sheet dynamics revealed

A new study has revealed the Complex pattern of Greenland Ice Sheet dynamics and  provided the first comprehensive picture of how Greenland's glaciers have changed over the past decade.

The findings of the study were published in the journal Proceedings of the National Academy of Sciences (PNAS) on 15 December 2014.

The research was conducted at the University at Buffalo by a team of researchers led by geophysicist Beata Csatho.

Findings of the study
• The scientists were able to provide new estimates of annual ice loss at high spatial resolution as the current models fail to accurately capture how the entire Greenland Ice Sheet is changing.
• The Greenland Ice Sheet lost about 243 metric gigatons of ice annually from 2003-09. This loss is estimated to have added about 0.68 millimeters of water to the oceans annually.
• Most of the outlet glaciers have been thinning during the last two decades, interrupted by episodes of decreasing thinning or even thickening.
• However, the intricate spatiotemporal pattern of dynamic thickness change suggests that regardless of the forcing responsible for initial glacier acceleration and thinning, the response of individual glaciers is modulated by local conditions.
• There are 242 outlet glaciers wider than 1.5 km on the Greenland Ice Sheet and their behavior is complex in space and time. The local climate, geological conditions and the local hydrology, all of these factors have an effect.

Study Process
The study was carried out by using the activity of four well-studied glaciers, Jakobshavn, Helheim, Kangerlussuaq and Petermann to forecast how the entire ice sheet will dump ice into the oceans.

However, the research shows that activity at these four locations may not be representative of what is happening with glaciers across the ice sheet.

The study includes presentation of detailed reconstruction of surface elevation changes of the Greenland Ice Sheet from NASA’s laser altimetry data.

The information is crucial for developing and validating numerical models that predict how the ice sheet may change and contribute to global sea level over the next few hundred years

Significance of the Study
• Time series at nearly 100000 locations allow the characterization of ice sheet changes at scales ranging from individual outlet glaciers to larger drainage basins and the entire ice sheet.
• The record shows that continuing dynamic thinning provides a substantial contribution to Greenland mass loss.
• The large spatial and temporal variations of dynamic mass loss and widespread intermittent thinning indicate the complexity of ice sheet response to climate forcing.