Carbon is taken out of the atmosphere through several natural and technological processes collectively known as carbon removal or carbon dioxide removal (CDR). The primary natural method is photosynthesis, where plants absorb carbon dioxide from the air and store it in their biomass and soils. Other natural sinks include oceans, which absorb CO2, and processes that form carbonates, like limestone deposits. Key methods of carbon removal include:

• Afforestation and reforestation: Planting new forests or restoring damaged ones, which absorb CO2 through tree growth.
• Soil carbon sequestration: Agricultural practices that increase carbon stored in soils.
• Biochar: Creating and burying charcoal to lock carbon in soils.
• Direct air capture: Machines that pull CO2 directly from the atmosphere for storage underground.
• Enhanced mineralization: Spreading crushed rocks on land to chemically absorb CO2.
• Ocean-based approaches: Such as ocean alkalinization and fertilization to boost carbon uptake by marine ecosystems.

These methods work to lock carbon away for long periods, helping to mitigate climate change by reducing atmospheric CO2 levels.