Review: Review: ONE Annual Lecture 2026 – Carbon removal: Are science and policy keeping up with the market?
by Alison McCookView the associated event for this review
Anthropogenic carbon dioxide emissions are driving catastrophic climate change, with large-scale, unpredictable and potentially irreversible effects. Rapid emissions reductions are necessary, but almost every feasible pathway to net zero also relies on some – often a lot of – carbon dioxide removal (CDR). How can CDR be scaled at the required pace while balancing environmental protection and precaution? Is policy lagging behind CDR science, or are CDR markets hurtling ahead of the science?
These questions were central to the 2026 Oxford Networks for the Environment annual lecture, delivered by Professor Gideon Henderson, Professor of Earth Sciences and former Chief Scientific Advisor at Defra. Professor Henderson set out the case for large-scale global CDR, reviewed the major CDR methods and their limitations, before asking what we need to do as demand for CDR credits grows to ensure credits have real climate value and do not cause unintended environmental harm. The lecture was followed by a panel discussion featuring Dr Steve Smith, Arnell Associate Professor of Greenhouse Gas Removal, and Dr Jessica Omukuti, Research Fellow on the Politics of Net Zero in the Global South.
The CDR landscape
Professor Henderson outlined the practical limits on the speed and extent of emissions reductions. Despite significant success in transitioning the energy sector, fully decarbonising energy systems remains challenging without long-term dispatchable power, while emissions reductions in sectors such as agriculture are constrained by slow cultural change. Although CDR is generally more expensive than emissions reductions, it will be unavoidable: estimates suggest that 7–9bn tonnes of CDR will be required annually by 2050.
This will require an extraordinarily rapid build-out of CDR capability, creating a fertile landscape for CDR markets. Around 11bn USD has already been spent on CDR at an average price of USD 260 per tonne (far above the EU Emissions Trading Scheme carbon price). However, only 2.7% of purchased CDR has been delivered.
These markets span a range of CDR methods at varying stages of maturity. Professor Henderson presented a taxonomy of CDR, categorised by removal mechanism (biological, natural inorganic reactions, or engineered) and storage location (living land vegetation, soil and dead land vegetation, geological, oceans and the built environment).
Among geological methods, Professor Henderson noted the relative nascency of Direct Air Carbon Capture and Storage (DACCS), with only 1,600 tonnes of CO2 removed so far – equivalent to 30 seconds’ worth of flights currently in the air. BioEnergy with Carbon Capture and Storage (BECCS) is further progressed, with 40,000 tonnes removed and greater capture efficiency, but long-term BECCS capacity remains constrained by limited availability of waste biomass (and using non-waste biomass would involve environmentally damaging land use changes).
Professor Henderson delved deeper into enhanced silicate rock weathering. This involves spreading silicate in rainy areas, accelerating natural reactions that draw CO₂ out of the atmosphere. Enhanced weathering has delivered around 9,000 tonnes of CDR and is cheaper than other geological CDR. However, Professor Henderson noted that current capacity projections are likely unrealistic, representing a 500% increase from natural weathering rates, and may be environmentally damaging: each tonne of CO₂ removed requires roughly four tonnes of mined basalt. Geochemical evidence also suggests actual CO₂ removal may be 10 times lower than modelled estimates.
CDR policy challenges
Given the technical constraints facing geological CDR, Professor Henderson contended that there is a growing mismatch between CDR technology, markets and policy. Regulation of CDR remains limited or non-existent for many techniques, while both buyers and sellers of CDR credits are incentivised to transact rapidly regardless of quality. Regulation must therefore balance environmental protection and ensuring verifiable CO₂ removal while still encouraging innovation and rapid scale-up.
As Dr Omukuti noted during the panel discussion, regulatory vacuums can stimulate innovation but also carry significant risks. CDR technology needs to “speak back to regulation [so they can] inform each other and learn from each other”. Professor Henderson agreed, stating that regulation “needs to be informed and flexible as it develops”. As a former environmental regulatory lawyer now studying sustainability science, this message strongly resonates.
Universities and scientists, Professor Henderson argued, have a critical role in overcoming this divide, and must be open-minded and analytical about scale-up options. He highlighted that only two reservoirs offer large-scale, long-term CO₂ storage potential: subsurface geological formations (estimated capacity of less than 12,000 gigatonnes) and the oceans (which store around 145,000 gigatonnes of CO₂). On this basis, Professor Henderson emphasised the importance of careful but clear-eyed research into ocean alkalinity enhancement to boost oceanic CO2 uptake. Despite significant barriers (including insufficient knowledge of environment consequences, weak measurement, reporting, and verification frameworks, and the possibility that the approach could be restricted under international maritime law), around 2,500 tonnes of CDR have already been delivered using this technique. Professor Henderson stated “the potential benefit is just too large to ignore.”
Relatedly, both the lecture and the subsequent panel noted that scaling CDR will require the participating of big companies – often fossil fuel companies. Professor Henderson described the acquisition of a major DACCS provider by OxyPetroleum as “unequivocally a good thing for future of the climate”, allowing the provider to expand their operations. During the panel, Steve Smith agreed and also noted the key role other industries will play in CDR (such as agriculture).
Conclusion
Professor Henderson was clear: extensive CDR is necessary to avoid the worst impacts of climate change and adoption of even riskier responses such as solar radiation management. The socio-economics and technology of CDR, however, are far less clear. Although CDR techniques remain in their infancy, CDR markets are geared toward rapid credit sales, driven by corporate demand, developer incentives, and venture capital expectations.
Too few projects consider how the socio-economic and technical components of CDR coincide. The 2026 ONE annual lecture highlighted two examples of this disconnect: enhanced rock weathering appears overhyped by markets, while ocean alkalinity enhancement is under-researched and may be banned under international law despite its promise. Professor Henderson called upon researchers to bridge the growing gap between technical solutions and socio-economics to ensure the CDR we need is delivered rapidly, reliable and with minimal environmental harm.