Earth’s crust uplift sheds new light onto climate change

A novel study looking at the Earth’s activity beneath Greenland sheds new light onto the effects of climate change – as per usual, it is not good news.

New GPS-based study suggests past and present-day ice loss measures have been underestimated (credit: Michael Bevis)

New GPS-based study suggests past and present-day ice loss measures have been underestimated (credit: Michael Bevis)

The research, published last week in Science Advances, was led by Shfaqat A. Khan of the National Space Institute at the Technical University of Denmark (DTU Space) and involved several scientists from Europe and the US. The team used data from GPS stations fixed on Greenland’s bedrock to measure uplifts of the Earth’s crust called ‘postglacial rebounds’ which are deeply connected with the evolution of the ice sheet sitting atop.

The idea is quite straightforward. The ice sheet sits on the Earth’s solid crust which is itself lying over the softer mantle underneath. When the ice sheet melts, the crust rises up in exactly the same way compressed foam would bounce up from under an object as this is removed. This means that just monitoring the change in elevation of the ice sheet to measure the effects of climate change – as we have done so far – is rather inaccurate. Such measure must take into account the Earth’s crust uplift as well, which is exactly what the team of researchers at DTU Space did in this new study.

“This research is a great first step toward better understanding how geologic processes below the surface of the Earth influence ice loss and, ultimately, sea level rise,” says Prof Beata Csatho, involved in the study. “It opens up new opportunities for better understanding how the ice sheet is changing and interacting with the rocky layers of the Earth below it.”

The GPS data used by the team of researchers capture the postglacial uplift of the crust with unprecedented detail, showing that previous studies are likely to have underestimated past and present-day ice mass loss.  “We’ve underestimated the rate of ice loss by about 7.6 per cent,” said Michael Bevis of The Ohio State University, one of the study’s co-authors.

The study also stresses the fact that the mantle underneath Greenland is not uniform, which is a factor that should be taken into account as well. In the southeast region, for instance, the uplift has been rather high, up to 12 millimetres per year, hinting that the mantle there may be hotter and less viscous – hence springier. “It’s a very exciting study,” Csatho says. “It’s a new and different way of understanding the ice sheet and this critical process of uplift.”

Here is a link to the video showing the phenomenon in action.

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Carlo Bradac

Carlo Bradac

Dr Carlo Bradac is a Research Fellow at the University of Technology, Sydney (UTS). He studied physics and engineering at the Polytechnic of Milan (Italy) where he achieved his Bachelor of Science (2004) and Master of Science (2006) in Engineering for Physics and Mathematics. During his employment experience, he worked as Application Engineer and Process Automation & Control Engineer. In 2012 he completed his PhD in Physics at Macquarie University, Sydney (Australia). He worked as a Postdoctoral Research Fellow at Sydney University and Macquarie University, before moving to UTS upon receiving the Chancellor Postdoctoral Research and DECRA Fellowships.

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