Carbon dioxide removal

Carbon dioxide removal (CDR) is defined as “Anthropogenic activities removing carbon dioxide (CO₂) from the atmosphere and durably storing it in geological, terrestrial, or ocean reservoirs, or in products. It includes existing and potential anthropogenic enhancement of biological or geochemical CO₂ sinks and direct air carbon dioxide capture and storage (DACCS), but excludes natural CO₂ uptake not directly caused by human activities.”

Source: IPCC (2021) AR6 WGI Annex VII, Glossary, pg. 2221

“All available studies require at least some kind of carbon dioxide removal to reach net zero; that is, there are no studies where absolute zero GHG or even CO₂ emissions are reached by deep emissions reductions alone.”

Source: IPCC (2022) AR6 WGIII Chapter 3, FAQ 3.2, pg. 385

“Most modelled pathways that likely limit warming to 2°C (>67%) above pre-industrial levels and below use land-based CO₂ removal such as afforestation/reforestation and BECCS to achieve net zero CO₂ and net zero GHG emissions even while some CO₂ and non-CO₂ emissions continue to occur. Pathways with more demand-side interventions that limit the amount of energy we use, or where the diet that we consume is changed, can achieve net zero CO₂, or net zero GHG emissions with less carbon dioxide removal (CDR).”

Source: IPCC (2022) AR6 WGIII Chapter 3, FAQ 3.2, pg. 385

“Deliberate carbon dioxide removal (CDR) from the atmosphere has the potential to compensate for residual CO₂ emissions to reach net zero CO₂ emissions or to generate net negative CO₂ emissions. In the same way that part of current anthropogenic net CO₂ emissions are taken up by land and ocean carbon stores, net CO₂ removal will be partially counteracted by CO₂ release from these stores (very high confidence). Asymmetry in the carbon cycle response to simultaneous CO₂ emissions and removals implies that a larger amount of CO₂ would need to be removed to compensate for an emission of a given magnitude to attain the same change in atmospheric CO₂ (medium confidence). CDR methods have wide-ranging side-effects that can either weaken or strengthen the carbon sequestration and cooling potential of these methods and affect the achievement of sustainable development goals (high confidence).”

Source: IPCC (2021) AR6 WGI TS.3.3.2, pg. 99