San Francisco, US: Scientists have produced the most detailed map yet of the White Continent’s underbelly – its rock bed. Simply called BEDMAP, it provides a view of the landscape beneath the ice and incorporates decades of survey data acquired by planes, satellites, ships and even people on dog-drawn sleds.
The map represents critical knowledge in the quest to understand how Antarctica might respond to a warming world. Scientists are currently reporting significant changes at the margins of the continent, with increasing volumes of ice now being lost to the ocean, raising global sea levels. The type of information contained in BEDMAP will help researchers forecast the pace of future events, says Hamish Pritchard from the British Antarctic Survey (BAS).
This is the second generation of the digital BEDMAP. The first version, which was produced in 2001, incorporated 1.9 million measurement points. For BEDMAP2, the sampling has been raised to more than 27 million points on a grid spacing of 5km.
The project has benefited greatly from the large number of airborne radar surveys that have been flown in recent years. Unlike rock, ice is transparent to radar. So by firing microwave pulses through the overlying sheet and recording the return echoes, scientists can plot both the depth of the rock bed and – by definition – the thickness of the ice covering. Instrumented planes, guided by GPS, will now fly back and forth across the ice in campaigns that can last weeks at a time.