The most detailed model of the Earth’s surface ever

Landscape development over the last 100 million years. Credit: Dr. Tristan Salles, University of Sydney / AAAS

An advanced digital tool can help us understand the past and predict the evolution of the Earth’s surface.

The interaction between climate, tectonic activity and the passage of time results in formidable forces that shape the appearance of our planet. The gentle erosion caused by rivers only adds to this, turning what appears to be an unchanging rock in reality into a constantly evolving surface.

But our understanding of this intricate process has been limited at best.

Scientists have published new research that reveals a detailed and dynamic model of Earth’s surface over the past 100 million years.

In collaboration with researchers in France, geoscientists from the University of Sydney have published this new model in the prestigious journal Science.

Animation of landscape dynamics model over the last 100 million years showing landscape erosion and sediment deposition. Credit: Dr. Tristan Salles, The University of Sydney

For the first time, it provides a high-resolution understanding of how today’s geophysical landscapes were created and how millions of tons of sediment have flowed to the oceans.

Lead author Dr. Tristan Salles, from the University of Sydney School of Geosciences, said: “To predict the future, we need to understand the past. But our geological models have provided only a fragmented understanding of how our planet’s recent physical features formed.

“If you’re looking for a high-resolution continuous model of the interaction between river basins, global erosion and sediment deposition over the last 100 million years, it just doesn’t exist. So it’s a big advance. It’s not just a tool to help us to examine the past, but it will also help scientists understand and predict the future.”

Tristan Salles

Lead author Dr. Tristan Salles from the School of Geosciences at the University of Sydney. Credit: Stefanie Zingsheim, University of Sydney

Using a framework that incorporates geodynamics, tectonic and climatic forces with surface processes, the scientific team has presented a new high-resolution dynamical model of the last 100 million years (down to 10 kilometres), divided into million-year frames.

Other author Dr. Laurent Husson of the Institut des Sciences de la Terre in Grenoble, France, said: “This unprecedented high-resolution model of the Earth’s recent past will equip geoscientists with a more complete and dynamic understanding of the Earth’s surface.

“Critically, it captures the dynamics of sediment transfer from land to the oceans in a way we haven’t been able to before.”

World map animation of landscape development over the last 100 million years. Credit: Dr. Tristan Salles, University of Sydney

Dr. Salles said that understanding the flow of terrestrial sediment into marine environments is critical to understanding today’s ocean chemistry.

“Given that ocean chemistry is changing rapidly due to anthropogenic climate change, a more complete picture can help our understanding of marine environments,” he said.

The model will allow scientists to test different theories about how the Earth’s surface will respond to changing climate and tectonic forces.

Further, the research provides an improved model for understanding how the transport of soil sediment regulates the planet’s carbon cycle over millions of years.

“Our results will provide a dynamic and detailed background for researchers in other fields to develop and test hypotheses, such as in biochemical circuits or in biological evolution.”

Reference: “Hundred million years of landscape dynamics from catchment to global scale” by Tristan Salles, Laurent Husson, Patrice Rey, Claire Mallard, Sabin Zahirovic, Beatriz Hadler Boggiani, Nicolas Coltice and Maëlis Arnould, 2 March 2023, Science.
DOI: 10.1126/science.add2541

The study was funded by the Australian Government and the Australian Research Council.

The authors Dr. Salles, Dr. Claire Mallard and Ph.D. student Beatriz Hadler Boggiani are members of the EarthColab Group and Associate Professor Patrice Rey and Dr. Sabin Zahirovic is part of the EarthByte Group. Both groups are at the School of Geosciences at the University of Sydney.

The research was carried out in collaboration with French geoscientists from CNRS, France, Université Lyon and ENS Paris.

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