Environmental Science
Carbon Sequestration
Quick fact
The world's soils hold more carbon than the atmosphere and all plants combined – about 2,500 billion tonnes versus 800 billion tonnes in the atmosphere.
Why this is interesting
You know trees absorb carbon dioxide, but did you know that the ground beneath your feet and even the ocean can trap carbon for thousands of years? How does this invisible process work?
Read the full explanation
Understanding Carbon Sequestration
Carbon sequestration is nature's way of cleaning the air. Just as a sponge soaks up water, certain parts of our planet soak up excess carbon dioxide. Plants are the star players: during photosynthesis, they take CO2 from the air, use sunlight to turn it into food, and store carbon in their stems, leaves, and roots. When plants die, some of that carbon gets locked into the soil. The ocean also absorbs CO2 directly from the air. These natural 'carbon sinks' have kept our climate stable for millions of years. Now, humans are also developing technologies to capture CO2 from power plants and even directly from the air, and then store it deep underground.
A deeper explanation
The core mechanism of carbon sequestration relies on moving carbon from the fast, atmospheric part of the carbon cycle into long-term reservoirs. In natural terrestrial sequestration, plants convert CO2 into organic carbon. Decomposers break down some of it, releasing CO2 back, but a fraction becomes soil organic matter that can persist for centuries. The ocean sequesters carbon through two main paths: the solubility pump, where cold, dense water carries dissolved CO2 to the deep sea, and the biological pump, where marine organisms absorb CO2 and sink to the ocean floor as detritus. Engineered sequestration involves capturing CO2 from point sources (like cement plants) using chemical absorbents, then compressing it into a liquid and injecting it into porous rock formations thousands of meters underground. The rock’s tiny pores trap the CO2, and over time it may react with minerals to form stable carbonates. This matters because even if we stop emitting CO2, natural sinks alone cannot absorb the excess quickly enough – enhancing sequestration is crucial to meet climate targets.