In a recent study published in February 2023, researchers have discovered that Earth absorbs more carbon from the atmosphere than previously believed, challenging existing equations and climate change projections. The updated findings indicate that around one-third of the carbon that enters Earth's interior remains stored there for the long term, contrary to the previous assumption that most of it reappeared through volcanic eruptions.
Understanding the operation and evolution of deep carbon stores, where a significant portion of Earth's carbon is located, is crucial for comprehending the consequences of atmospheric carbon dioxide and habitability on the planet's surface.
The process through which carbon is drawn deep into Earth is plate subduction, in which tectonic plates collide and warp, burying carbon-storing remnants of organisms and seashells underground. Researchers simulated the chemical reactions occurring in tectonic plate rock using a particle accelerator, creating high pressure and temperature conditions in subduction zones.
They discovered carbonate rocks become less soluble as they are transported deeper into the mantle, making them less likely to be drawn into the fluids supplying volcanoes. Instead, most carbonate sinks further down and can eventually transform into diamonds, sequestering carbon gathered from the atmosphere and ocean sediments.
The stability of these minerals suggests that they can lock up carbon dioxide from the atmosphere into solid mineral forms, potentially leading to negative emissions. Understanding this process better could contribute to finding ways to accelerate carbon storage in the solid Earth, offering a potential solution to the climate crisis. However, it is important to note that while carbon capture from the atmosphere is valuable, reducing global emissions remains the most critical action in addressing climate change.
While the research provides insights into the carbon cycle between the atmosphere, oceans, and Earth's interior, studying what occurs beneath the Earth's surface over long timescales is challenging. Subduction zones differ in geological and chemical composition, requiring further studies to gather more data and refine estimates.
The researchers aim to investigate carbonate solubility across a wider range of temperatures, pressure, and fluid compositions. This study enhances our understanding of Earth's carbon dynamics, but comprehensive action to reduce emissions is still imperative in addressing the climate crisis.