Tidal motion influences Antarctic ice sheet

Dec 20, 2006
Greenland Ice

New research into the way the Antarctic ice sheet adds ice to the ocean reveals that tidal motion influences the flow of the one of the biggest ice streams draining the West Antarctic Ice Sheet.

This unexpected result shows that the Rutford Ice stream (larger than Holland) varies its speed by as much as 20% every two weeks. Ice streams – and the speed at which they flow – influence global sea level. Understanding their behaviour has been a priority for some time. On average the Rutford Ice Stream moves forward by one metre every day.

Reporting this week in the journal Nature, British Antarctic Survey (BAS) glaciologist Hilmar Gudmundsson says,

‘We've never seen anything like this before. The discovery that the spring-neap tidal cycle exerts such a strong influence on an ice stream tens of kilometres away is a total surprise. For such a large mass of ice to respond to ocean tides like this illustrates how sensitively the Antarctic Ice Sheet reacts to environmental changes. Glaciologists need now to rethink how the Antarctic Ice Sheets reacts to external forces. '

The variations in flow of the Rutford Ice Stream are related to the vertical motion of the ocean caused by the gravitational effects of the sun and moon. Every two weeks sees large tides, the so-called spring tides which are followed by small tides, the neap tides. Scientists expect movement of the floating ice shelves, but the Rutford Ice Stream is grounded in the shallow waters of the Antarctic continental shelf.

So far, Rutford Ice Stream is the only ice stream where this type of temporal variation has been observed, but it is likely that the phenomenon is widespread, and so important to incorporate in computer models predicting the future contribution of the ice sheets to sea level rise.

Source: British Antarctic Survey

Explore further: Satellites sees a question mark in Tropical Storm Ana

add to favorites email to friend print save as pdf

Related Stories

Sediment wedges not stabilizing West Antarctic Ice Sheet

Sep 03, 2013

The stability of the West Antarctic Ice Sheet is uncertain as climate changes. An ice sheet such as the West Antarctic Ice Sheet that is grounded well below sea level on a bed that slopes toward the interior of the sheet ...

LSU gets to the bottom of things -- in Antarctica

Nov 24, 2009

Antarctica has long held secrets of the earth's history locked in its icy depths, and until recently, there has been very little information on the environments that have been sealed beneath miles of ice for millions of years. ...

Recommended for you

Asbestos likely more widespread than previously thought

4 hours ago

Naturally occurring asbestos minerals may be more widespread than previously thought, with newly discovered sources now identified within the Las Vegas metropolitan area. The asbestos-rich areas are in locations not previously ...

User comments : 0