How Moving Tectonic Plates Shape Earth’s Climate More Than Scientists Thought

Scientists have discovered that the movement of Earth's tectonic plates has shaped the planet's climate far more significantly than previously understood, challenging decades of scientific assumptions about what drives major climate shifts.

Researchers from the Universities of Melbourne and Sydney analyzed 540 million years of Earth's climate history and found that carbon released from the gaps and ridges deep under the ocean—where tectonic plates move apart—has been the main driver of transitions between ice ages and warm climates. This finding overturns the conventional wisdom that volcanic activity from colliding tectonic plates was the primary source of atmospheric carbon.

"Carbon gas released from gaps and ridges deep under the ocean from moving tectonic plates was instead likely driving major shifts between icehouse and greenhouse climates for most of Earth's history," said Dr Ben Mather, lead researcher at the University of Melbourne.

The work, published in Nature Communications Earth and Environment, used computer models to reconstruct how carbon moved between volcanoes, oceans, and deep within the Earth over hundreds of millions of years. The team paired global plate tectonic reconstructions with carbon-cycle modelling to trace how carbon was stored, released, and recycled as continents shifted across the planet.

Background

For many years, scientists believed that volcanic chains formed by colliding tectonic plates—like those around the Pacific Ring of Fire—were Earth's main natural source of atmospheric carbon. This assumption shaped how researchers understood past climate changes and built models to predict future climate shifts.

However, the new research reveals a more complex picture. While volcanic activity does release carbon, it only became a major carbon source in the last 100 million years. Before that, the real driver of climate change was the carbon released at mid-ocean ridges, where two tectonic plates move away from each other. At these spreading zones, magma rises to the surface to create new ocean crust, releasing massive amounts of carbon dioxide into the atmosphere.

At the same time, at ocean trenches where plates converge and collide, oceanic plates are pulled down and recycled back into the deep Earth. This process, called subduction, carries carbon back into Earth's interior while also releasing some carbon dioxide through volcanic activity. Together, these processes form what researchers call a "tectonic carbon conveyor belt" that shifts enormous amounts of carbon between the deep Earth and the surface.

Key Details

The research explains several major climate transitions in Earth's history. During the Cretaceous period, roughly 100 million years ago, the planet experienced a hothouse climate with much warmer temperatures than today. The study shows this was caused by very fast-moving tectonic plates, which dramatically increased carbon dioxide emissions from mid-ocean ridges.

About 50 million years ago, Earth's climate began to cool dramatically, eventually leading to the modern icehouse climate with temperatures roughly 7 degrees Celsius cooler than the warm Cretaceous period. The research reveals this cooling happened through a complex mechanism involving mountain building, continental erosion, and the burial of organic material on the seafloor.

When tectonic plates slow down due to collisions, they trigger mountain building—such as the formation of the Himalayas and the Alps over the last 50 million years. As these mountains form, they begin to erode. Rainwater containing carbon dioxide reacts with mountain rocks, breaking them down. Rivers carry the dissolved minerals into the sea, where marine organisms use them to build their shells. These shells eventually become part of carbon-rich marine sediments that store carbon away from the atmosphere, causing the planet to cool.

"This research adds to a large pool of evidence that the amount of carbon in the Earth's atmosphere is a key trigger to cause major swings in climate," Dr Mather said.

The Broader Earth Systems View

The findings contribute to a growing understanding that plate tectonics does not operate in isolation from other Earth systems. Recent research has also shown that climate can influence tectonic activity. Studies of Lake Turkana in the East African Rift Valley found that climate-driven changes in water levels affected fault activity and magma production, suggesting that surface processes like climate can shape the movement of Earth's plates.

Similarly, research on glacial melting in places like Alaska, the Himalayas, and the Alps has shown that as ice sheets disappear due to climate change, the reduction in weight on Earth's surface can trigger more frequent earthquakes and faster fault movements in tectonically active regions.

What This Means

The research provides important context for understanding the current climate crisis. Human activities are now releasing carbon far faster than any natural geological process observed in the past. While tectonic processes may have taken hundreds of thousands or millions of years to shift Earth's climate significantly, human-caused emissions are changing the atmosphere in just decades.

The findings also suggest that understanding how Earth controlled its climate in the past might help scientists develop solutions for the future. Some researchers have proposed that natural processes like rock weathering could be enhanced to remove carbon from the atmosphere. Spreading olivine, a mineral found in basalt rocks, on beaches could potentially absorb up to a trillion tonnes of carbon dioxide from the atmosphere, according to some estimates.

However, scientists emphasize that reducing carbon emissions quickly remains essential to avoid catastrophic global warming. While geological processes, with human assistance, may eventually play a role in maintaining Earth's stable climate, the speed of current warming means that cutting emissions must be the immediate priority.

The research demonstrates that Earth's climate system is interconnected in ways scientists are still discovering. As researchers develop more sophisticated models of how the planet works, they gain better tools to predict future climate changes and evaluate potential solutions.