Revealed in New Map ... What Antarctica Looks Like Without Ice

Submitted by SadInAmerica on Thu, 03/14/2013 - 9:28pm.


Scientists at the British Antarctic Survey have been working with a host of international collaborators to present the most detailed map yet of Antarctica's landmass. Bedmap2 reveals a landscape of mountain ranges and plains cut by gorges and valleys much deeper than previously seen. ~ Videos

In addition, the map allows scientists to analyze, in much greater detail, the bed below the Antarctic ice sheet.

A different view: Antarctica without the ice. Several features of the bed have been revealed for the first time including a new deepest point. The bed under the Byrd Glacier in Victoria Land is 2,870 metres below sea level making it the lowest point on any of the Earth's continental plates.

Credit: British Antarctic Survey

The map was compiled using data sets collected from radio echo sounding measurements, seismic techniques, satellite readings and cartographic data.

A number of key statistics emerge...

* The volume of ice in Antarctica is 4.6% greater than previously thought.

* The mean bed depth of Antarctica, at 95 metres, is 60 m lower than estimated.

* The volume of ice that is grounded with a bed below sea level is 23% greater than originally thought meaning there is a larger volume of ice that is susceptible to rapid melting.

* The ice that rests just below sea level is vulnerable to warming from ocean currents.

* The total potential contribution to global sea level rise from Antarctica is 58 metres, similar to previous estimates but a much more accurate measurement.

* The new deepest point, under Byrd Glacier, is around 400 metres deeper than the previously identified deepest point.

Peter Fretwell, from the British Antarctic Survey, says...

"The new Bedmap shows, with unprecedented detail, the bedrock beneath the ice sheets of Antarctica. Before we had a regional overview of the topography, but this new map, with its much higher resolution, shows the landscape itself; a complex landscape of mountains, hills and rolling plains, dissected by valleys troughs and deep gorges."


Dr Hamish Pritchard, co-lead author of the study, says: 

"The Bedmap2 project is about more than making a map of the landscape. The data we've put together on the height and thickness of the ice and the shape of the landscape below are fundamental to modelling the behaviour of the ice sheet in the future.

This matters because in some places, ice along the edges of Antarctica is being lost rapidly to the sea, driving up sea level. Knowing how much the sea will rise is of global importance, and these maps are a step towards that goal."  

In most parts of Antarctica the sub-glacial landscape is visible in much greater detail than was previously available and the improved data coverage has in many areas revealed the full scale of mountain ranges, valleys, basins and troughs, only fragments of which were previously indicated in local surveys.

The derived statistics for Bedmap2 show that the volume of ice contained in the Antarctic ice sheet (27 million km3) and its potential contribution to sea-level rise (58 m) are similar to those of Bedmap1.

The mean thickness of the ice sheet is 4.6% greater, the mean depth of the bed beneath the grounded ice sheet is 72m lower and the area of ice sheet grounded on bed below sea level is increased by 10 %.

Bedmap2 ice thickness grid.

Bedmap2 bed elevation grid. Although difficult to see at this scale, the bed elevation in areas where the main source of bed elevation data is gravi-metric has inherited roughness from the surface grid.




Alton Parrish - March 14, 2013 - posted at BeforeIt'sNews


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Submitted by SadInAmerica on Thu, 03/14/2013 - 9:28pm.