Using boulders to determine glacial thinning
Rocks and boulders collected from glaciers in Antarctica could help scientists determine glacial behavior and impacts of climate change along the West Antarctic Ice Sheet.
Scientists from the British Antarctic Survey, Durham University and the Alfred Wegener Institute for Polar and Marine Research collected football (soccer one can assume?) sized boulders. It sounds like the researchers used a form of cosmogenic dating to determine how long the boulders had been exposed to sunlight.
Image credit: NASA
Initial results show that Pine Island Glacier has â€˜thinnedâ€™ by around 4 centimetres per year over the past 5,000 years, while Smith and Pope Glaciers thinned by just over 2 cm per year during the past 14,500 years. These rates are more than 20 times slower than recent changes: satellite, airborne and ground based observations made since the 1990s show that Pine Island Glacier has thinned by around 1.6 metres per year in recent years.
Co-author Dr Mike Bentley from the University of Durham said, â€œWhen rocks are left high and dry by thinning glaciers they are exposed to high energy cosmic rays which bombard the rock. This creates atoms of particular elements that we can extract and measure in the laboratory – the longer they have been exposed the greater the build-up of these elements. The discovery that we can place a fix on when rocks were left behind by the ice has revolutionised our understanding of how the Antarctic ice sheet has behaved in the past.”
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