Planetary changes

Discovering our changing planet: a perfect France–Australia partnership

Professor Kurt Lambeck is one of Australia’s most eminent scientists—a geophysicist who revealed how the Earth changes shape and how these changes are tied to sea levels, the movement of continents, and the orbits of satellites. Vital to his career have been French collaborations that now span almost half a century.

In 1970 Kurt took a position at the Paris Observatory (Université Paris Sciences et Lettres), after working at the Harvard and Smithsonian Observatories on NASA-supported programs for measuring the Earth’s shape and gravity field. He helped to expand the then-emerging French program using satellites to study the Earth and for navigation. He had planned to visit France for a single year; in the end he stayed for eight.

“I quickly learned there was little I could teach them about satellite geodesy, but I could define new application areas,” Kurt says.

So, he steered the program towards geophysics, measuring: the slow deformations in the planet and in its gravity field; the planetary tides; Earth’s irregular rotation; and the changing oceans and ice caps. France is still a leader in these areas today.

“Ultimately—through my students and colleagues—this early work has led to major new developments in these areas of global geophysics.”

In 1977, Kurt returned to Australia to take up a position at the Australian National University in Canberra, where he still works today. He has maintained his connection with French satellite projects, though now primarily as an end user of the results.

“Once I could no longer be involved in collecting and analysing the data, I started looking in more detail at what it said about the interactions between the solid planet and its oceans and atmospheres. And that turned out to be surprisingly complex.”

For example, Kurt realised that measuring small changes in Earth’s shape and gravity field could reveal how the planet’s crust is still bouncing back from the weight of icecaps that existed in ancient ice ages. This opened a new window into the planetary ice history that could only be understood by integrating the information with work from other kinds of geoscience as well as historical and archaeological records.

“The basic science, the field evidence, and the earlier satellite work came together. You can model sea levels and reconstruct what coastal environments looked like and think about what that meant for prehistoric humans.”

Kurt’s work was recognised in France when he was named a Chevalier de l’Ordre National de la Legion d’Honneur in 2013, and in Australia with the award of the 2018 Prime Minister’s Prize for Science.

Banner image: Kurt Lambeck’s French connections go back decades. Credit: Prime Minister’s Prizes for Science / WildBear