Carbon dioxide removal

Carbon dioxide removal (CDR), also known as carbon removal, greenhouse gas removal (GGR) or negative emissions, is a process in which carbon dioxide gas (CO₂) is removed from the atmosphere by deliberate human activities and durably stored in geological, terrestrial, or ocean reservoirs, or in products.^: 2221 In the context of net zero greenhouse gas emissions targets, CDR is increasingly integrated into climate policy, as an element of climate change mitigation strategies. Achieving net zero emissions will require both deep cuts in emissions and the use of CDR, but CDR is not a current climate solution. In the future, CDR may be able to counterbalance emissions that are technically difficult to eliminate, such as some agricultural and industrial emissions.^: 114

CDR methods include afforestation, reforestation, agricultural practices that sequester carbon in soils (carbon farming), wetland restoration and blue carbon approaches, bioenergy with carbon capture and storage (BECCS), ocean fertilization, ocean alkalinity enhancement, and direct air capture when combined with storage,^: 115 To assess whether negative emissions are achieved by a particular process, comprehensive life cycle analysis and monitoring, reporting, and verification (MRV) of the process must be performed.

As of 2023, CDR is estimated to remove around 2 gigatons of CO₂ per year, which is equivalent to 4% of the greenhouse gases emitted per year by human activities.^: 8. Equitable allocation of CDR suggest countries remove 17% of their residual emissions in 2040 to achieve 1.5℃ goal. However, there is significant uncertainty around this number because there is no established or accurate method of quantifying the amount of carbon removed from the atmosphere. There is potential to remove and sequester up to 10 gigatons of carbon dioxide per year by using those existing CDR methods which can be safely and economically deployed now.