Earth’s tectonic activity occasionally leads to the release of substantial amounts of carbon dioxide (CO₂), a process that influences our planet’s atmosphere and climate over immense timeframes. A recent study published in Geochemistry, Geophysics, Geosystems sheds light on this phenomenon, showing how tectonic carbon emissions from deep within Earth have likely impacted global climate across the last billion years. Led by R. Dietmar Müller, this research offers a refined view of carbon flux through tectonic mechanisms, illustrating how natural, deep-Earth emissions correlate with major shifts in Earth’s climate history.
Volcanoes, mid-ocean ridges, and undersea vents—all locations where tectonic plates meet or diverge—serve as gateways for CO₂ and other gases to escape from Earth’s mantle to the atmosphere. When tectonic plates shift, some regions experience significant volcanic eruptions and seafloor spreading, which release gases stored in magma chambers deep within the Earth. This deep-Earth carbon cycle, though slow and episodic, plays a critical role in shaping the planet’s atmospheric composition and climate over geological epochs. While these natural emissions are dwarfed by present-day human CO₂ emissions, they are thought to have had a profound influence on the climate over tens of millions to billions of years.
Previous models of tectonic CO₂ emissions primarily estimated carbon outgassing from volcanic activity at plate boundaries, especially in areas of intense tectonic collisions. However, tectonic plates also play an important role in trapping carbon. As plates collide and new crust forms along mid-ocean ridges, carbon can become sequestered within minerals in the Earth’s crust, effectively “locking away” CO₂ in solid form. This study builds on recent insights into plate tectonics over the past billion years to create a model that accounts for both CO₂ release and capture, offering a more nuanced view of Earth’s natural carbon flux.
The model’s findings show a strong correlation with known climatic transitions in Earth’s history. For instance, periods when the model indicates higher carbon release generally align with warmer climates. One such period is the Ediacaran, beginning around 653 million years ago, when Earth saw a significant rise in temperatures and complex multicellular life began to flourish. In contrast, colder periods, such as the “Snowball Earth” episodes from about 700 million to 600 million years ago, correspond to intervals when the model suggests lower CO₂ outgassing from tectonic activity. During these episodes, much of Earth’s surface is believed to have been covered in ice, possibly due in part to reduced tectonic emissions limiting greenhouse warming.
The study also sheds light on how the breakup of supercontinents may have influenced climate. For example, when the ancient supercontinent Pangea began to fragment approximately 200 million years ago, tectonic plates diverged, opening up new areas for magma to rise to the surface and release CO₂. This increase in volcanic and tectonic activity likely contributed to the warmer global temperatures observed during that period. The model thus supports the idea that tectonic shifts, including the breakup of major landmasses, have historically released large volumes of CO₂, leading to significant climate warming.
Overall, this study emphasizes that tectonic activity is a major driver of atmospheric CO₂ levels and has been crucial in determining Earth’s long-term climate cycles. Yet, despite recent advances in modeling these processes, many uncertainties remain. Factors such as the exact rates of carbon sequestration in newly formed crust and the variability of tectonic activity over different regions and periods complicate the picture. As a result, scientists continue to seek deeper understanding of the complex interplay between plate tectonics, volcanic activity, and the carbon cycle to better predict how these processes may influence Earth’s climate in the future.
The research highlights the enduring influence of Earth’s geological processes on its atmosphere and climate, underscoring the importance of studying tectonic-driven carbon emissions. As we face the current challenges of human-induced climate change, understanding these ancient, natural processes may offer a broader perspective on how Earth’s climate system responds to shifts in CO₂ levels, providing insights that could inform future climate strategies.