The movement of carbon in the Earth’s atmosphere, oceans, and continents, known as the carbon cycle, is a crucial process that regulates the planet’s climate. Various factors, including volcanic eruptions and human activities, release carbon dioxide into the atmosphere, while forests and oceans absorb this CO2. The balance between carbon emission and absorption plays a significant role in maintaining a healthy climate, and carbon sequestration is one approach to combatting climate change. A new study has revealed that the shape and depth of the ocean floor have a substantial impact on carbon sequestration in the ocean over the past 80 million years, explaining up to 50% of the changes in carbon depth sequestration previously attributed to other causes.
Researchers have long understood that the ocean, as the largest carbon absorber on Earth, directly influences the amount of atmospheric CO2. However, the specific effect of changes in seafloor topography on the ocean’s ability to sequester carbon has not been well understood until now. The study, led by UCLA doctoral student Matthew Bogumil, emphasizes the crucial role that seafloor bathymetry plays in the long-term carbon cycle. The shape and depth of the ocean floor are influenced by factors such as the relative positions of continents and oceans, sea level changes, and mantle flow, and it significantly impacts carbon storage in the ocean floor.
Published in the Proceedings of the National Academy of Sciences, the study reconstructed bathymetry over 80 million years and integrated this data into a computer model that measures marine carbon sequestration. The findings revealed that ocean alkalinity, calcite saturation state, and carbonate compensation depth are strongly influenced by changes in shallow ocean floor regions up to 600 meters, as well as deeper marine regions exceeding 1,000 meters. These parameters are crucial in understanding how carbon is stored in the ocean floor, with bathymetry alone accounting for 33%-50% of the observed variation in carbon sequestration during the Cenozoic era.
By recognizing the impact of ocean floor bathymetry on carbon sequestration, researchers can improve their understanding of marine-based carbon dioxide removal technologies to address climate change effectively. This knowledge may also help in the search for habitable planets beyond our solar system, as understanding the role of bathymetry in the carbon cycle can provide insights into planetary habitability. Moving forward, the researchers plan to conduct further simulations and models to explore how differently shaped ocean floors impact the carbon cycle, especially in early Earth when most of the land was submerged. This ongoing research aims to enhance our understanding of the Earth’s history and improve our ability to predict future climate changes.