To decrease atmospheric concentrations of greenhouse gases, Carbon dioxide removal (CDR) must be the physical, permanent, and net removal of greenhouse gases from the atmosphere.

The term “CDR” is used to refer to a variety of activities – not all of which lead to permanent storage of atmospheric CO2 – including direct air capture and storage (DACS), biomass with carbon capture and storage (bioCCS) forest management, biochar, enhanced weathering, and carbon farming, each of which has advantages, trade-offs, and uncertainties.

The three key components of any CDR activity are the carbon source, which must be atmospheric, the carbon sink, which must be monitorable and permanent, and the associated system and supply chains, whose emissions and impacts must be fully evaluated. 

In short:

• CDR must be sourced from the atmosphere, permanently stored, verifiable, and must remove more than is emitted in the process.

• Removals are not an alternative to reducing emissions as quickly and drastically as possible.

• Deployment and scale-up of technologies and its targeted use are required. 

• Monitoring methodologies are needed now for carbon dioxide removal to deliver on its potential as a credible climate solution.

While rapid minimisation of emissions is the most important and urgent action required for preventing catastrophic climatic changes, reaching and maintaining net-zero will also require removing greenhouse gases from the atmosphere. According to the latest report of the UN’s Intergovernmental Panel on Climate Change, CDR is a necessary part of limiting global warming. Its three sequential roles are to help rapid massive-scale reductions to reach net-zero faster, to maintain net-zero by compensating for residual emissions, and to remove historical emissions.   

Most forms of proposed CDR are new technologies that do not exist at scale and their rapid deployment will require substantial political will. However, removing CO₂ from the atmosphere is resource-intensive, typically much more so than emission reductions, and subject to uncertainties around net impact, timing of the climate benefit, and potential side-effects. Therefore, it is fundamental that policy on CDR is grounded in honest and transparent scientific dialogue that respects the differences between CDR activities and their respective risks. 

Our work on carbon dioxide removal focuses on building a foundation of scientifically grounded definitions, guardrails, and accounting principles to support effective CDR scale-up which amplifies, rather than dilutes, climate action.