Earth’s Shifting Tectonic Plates Have Played a Bigger Role in Driving Climate Change Than Previously Thought

Earth’s climate has swung dramatically over geological time, alternating between frigid “icehouse” phases and warm “greenhouse” periods. These shifts have long been linked to changes in atmospheric carbon dioxide, but new research suggests the forces driving those changes are far more complex than previously understood.

A study published in Communications Earth & Environment finds that the movement of Earth’s tectonic plates plays a much larger role in regulating climate than scientists once believed. Crucially, carbon emissions are not dominated solely by regions where tectonic plates collide and volcanoes form. Areas where plates pull apart — such as mid-ocean ridges and continental rifts — are equally, and at times more, important.

Traditionally, volcanic arcs at converging plate boundaries were thought to be the main source of carbon dioxide released into the atmosphere. These volcanoes melt carbon-bearing rocks and vent the gas to the surface. However, the new research challenges this assumption by highlighting the importance of the “deep carbon cycle”.

Oceans absorb vast amounts of atmospheric carbon dioxide and lock it away in carbon-rich sediments on the seafloor. Over millions of years, tectonic plate movement carries these sediments across the planet. When they eventually reach subduction zones — where one plate sinks beneath another — their stored carbon is released back into Earth’s interior and, ultimately, the atmosphere.

By using computer models to reconstruct tectonic plate movements over the past 540 million years, researchers were able to link these processes to major climate transitions. During greenhouse periods, carbon release exceeded sequestration, raising atmospheric CO₂ levels and warming the planet. During icehouse periods, carbon burial in ocean sediments dominated, reducing CO₂ and triggering global cooling.

One key finding is the central role of deep-sea sediments in controlling atmospheric carbon dioxide. The balance between how much carbon is stored on the seafloor and how much is recycled through subduction largely determines whether Earth enters a warm or cold climate state.

The study also revises understanding of volcanic arcs. While they have been a major source of atmospheric carbon over the past 120 million years, this dominance coincides with the rise of planktonic calcifiers — microscopic marine organisms that convert dissolved carbon into calcite, forming vast carbonate sediments. These organisms evolved around 200 million years ago and spread widely about 150 million years ago, boosting the amount of carbon recycled through volcanic arcs.

Before their emergence, carbon emissions from mid-ocean ridges and continental rifts were the more significant contributors to atmospheric CO₂.

The findings offer a fresh perspective on how Earth’s internal processes have shaped long-term climate. Rather than being driven solely by atmospheric dynamics, Earth’s climate is deeply influenced by the slow, powerful movement of tectonic plates and the recycling of carbon between the oceans, crust and mantle.

Understanding this deep-time carbon cycle, the researchers say, can improve future climate models and provide valuable context as human activity rapidly alters atmospheric carbon dioxide levels.