Revealing the breathing Earth

21 Oct 2018

Author: Niall Byrne – Prime Minister’s Prizes for Science

Photography: Prime Minister’s Prizes for Science/WildBear

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Kurt Lambeck, Emeritus Professor at the Australian National University in Canberra, received this year's $250,000 Prime Minister’s Prize for Science for transforming our understanding of our living planet.
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Emeritus Professor Kurt Lambeck AO has revealed how our planet changes shape—every second, every day, and over millennia. These changes influence sea levels, the movement of continents, and the orbits of satellites.

Professor Lambeck's original work in the 1960s enabled accurate planning of space missions. It led him to use the deformation of continents during the ice ages to study changes deep in the mantle of the planet. It also led to a better understanding of the impact of sea level changes on human civilization in the past, present and future.

Today’s highly accurate GPS-based systems build on his work and enable precision agriculture, new ways to explore for minerals, and the remarkable navigation tools we all use in our smartphones.

“The Earth is remarkable,” he says. “It has this wonderful record of its history going back to almost its very beginning. Almost everywhere you look, you learn something new about what’s been going on in our planet. It’s a constant journey of discovery.”

His journey started with a Bachelor of Surveying from UNSW, then a PhD at Oxford University in space geodesy—precise measurement of the Earth using satellites. It was 1967 and humankind was rushing into space.

Lambeck discovered that the gravity field of the Earth was much more complex than anyone had thought. That turned out to be important for spaceflight, because the gravity field determines trajectories of satellites, and we needed better gravity field models to be able to navigate to the moon and beyond. But for Kurt, what was more important was the insight that changes in the planet’s gravity field were directly related to plate tectonics, the movements of continents on the Earth’s surface.

Changes in the Earth’s gravity field can help us look inside the planet today, but they can’t tell us what happened in the past. For that, Kurt turned to the ice ages, when much of the Earth was covered in ice sheets up to four kilometres thick. Fifty million cubic kilometres of ice stressed and deformed the continents, pushing them down into the Earth’s mantle. The continents are still rebounding from that stress. Parts of Sweden, for example, are rising at a metre a century, while southern England is sinking by 5cm a century.

Changing sea levels have had a major impact on the rise and fall of civilisations and will continue to do so in the future. Lambeck is now working with archaeologists in Europe, and with precision carbon dating equipment at ANU, to piece together a more precise understanding of past sea levels.

By measuring change over millions of years, thousands of years, and from day to day, Kurt and his colleagues can generate the best possible predictions of future sea levels so that local, national, and international governments can plan for a changing future.

His ideas have also seeded technological innovations that we use every day. Space geodesy has evolved the GPS navigation technology built into every smart phone.

In Australia, he guided the development of a comprehensive geodetic monitoring system called the AuScope network. Established with the support of the National Collaborative Research Infrastructure Strategy (NCRIS), the network consists of about 100 GPS stations, radio telescopes, and laser tracking systems, and enables us to track our location with sub-centimetre accuracy across the country.

“Today we can see the breathing of the Australian continent on a daily basis,” Lambeck says.

“We can watch the land rise and fall with the tides and observe the straining of the old continent as it collides with Southeast Asia. We can detect subtle variations in gravity that could indicate not only deep mineral deposits but also changes in groundwater through time.”

Precise navigation is also essential for autonomous vehicles on the road, on the farm and on mine sites.

“You need to keep them on the road, and if the road is shifting in your reference frame then you’re going to be in trouble, so you need to correct for that,” he says.

Lambeck has received more than 30 international awards and distinctions and served as President of the Australian Academy of Science from 2006 to 2010.

“Kurt Lambeck is without question Australia’s pre-eminent earth scientist in the fields of geodesy and geophysics, and a towering figure internationally,” says Andrew Gleadow AO, Emeritus Professor in Earth Science at the University of Melbourne.