Tectonic Plates Drive Earth's Climate More Than Previously Understood

Earth's Climate Controlled by Underground Forces

Scientists have discovered that the movement of tectonic plates beneath our feet has played a far greater role in shaping Earth's climate over the past 540 million years than previously understood. Using computer models to reconstruct how Earth moves carbon stored on tectonic plates, researchers were able to predict major greenhouse and icehouse climates over the last 540 million years .

Our planet has experienced dramatic climate shifts throughout its history, oscillating between freezing "icehouse" periods and warm "greenhouse" states. Scientists have long linked these climate changes to fluctuations in atmospheric carbon dioxide. However, new research reveals the source of this carbon – and the driving forces behind it – are far more complex than previously thought .

In fact, the way tectonic plates move about Earth's surface plays a major, previously underappreciated role in climate . The research, published in Communications, Earth and Environment, challenges long-held assumptions about what drives Earth's natural climate cycles.

Challenging Scientific Assumptions About Carbon Sources

At the boundaries where Earth's tectonic plates converge, we get chains of volcanoes known as volcanic arcs. Melting associated with these volcanoes unlocks carbon that's been trapped inside rocks for thousands of years, bringing it to Earth's surface. Historically, it's been thought these volcanic arcs were the primary culprits of injecting carbon dioxide into the atmosphere. Our findings challenge that view .

Instead, we suggest that mid-ocean ridges and continental rifts – locations where the tectonic plates spread apart – have played a much more significant role in driving Earth's carbon cycles throughout geological time . This discovery fundamentally changes how scientists understand the relationship between plate movement and atmospheric carbon levels.

This is because the world's oceans sequester vast quantities of carbon dioxide from the atmosphere. They store most of it within carbon-rich rocks on the seafloor. Over thousands of years, this process can produce hundreds of metres of carbon-rich sediment at the bottom of the ocean .

The Ocean Floor's Hidden Climate Role

One of the key takeaways from our study is the critical role of the deep-sea sediments in regulating atmospheric carbon dioxide. As Earth's tectonic plates slowly move, they carry carbon-rich sediments, which are eventually returned into Earth's interior through a process known as subduction. We show that this process is a major factor in determining whether Earth is in a greenhouse or icehouse state .

During greenhouse periods – when Earth was warmer – more carbon was released than trapped within carbon-carrying rocks. In contrast, during icehouse climates, the carbon sequestration into Earth's oceans dominated, lowering atmospheric carbon dioxide levels and triggering cooling .

This tectonic "carbon conveyor belt" operates on geological timescales, moving massive amounts of carbon between the deep Earth and surface. The Cretaceous hothouse climate was caused by very fast-moving tectonic plates, which dramatically increased CO₂ emissions from mid-ocean ridges. In the transition to the Cenozoic icehouse climate tectonic plate movement slowed down and volcanic CO₂ emissions began to fall .

Implications for Understanding Climate Change

"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. Understanding how Earth controlled its climate in the past highlights how unusual the present rate of change is" , according to University of Melbourne researcher Ben Mather.

The study sheds light on how exactly Earth's plate tectonics have helped to shape global climate over the past 540 million years . These findings provide crucial context for current climate models and help explain major historical climate transitions, from ancient ice ages to warm periods when dinosaurs thrived.

While these natural tectonic processes operate over millions of years, understanding them helps scientists better comprehend how carbon moves through Earth's systems. This knowledge becomes increasingly valuable as humanity grapples with rapid climate change driven by fossil fuel emissions occurring at unprecedented speeds compared to these geological processes.