The final document of the last United Nations Climate Change Conference, more commonly known as COP30, acknowledges that the world is approaching an overshoot – that is, exceeding the 1.5 °C global warming threshold. Reducing future emission will be essential, but no longer sufficient: we will also need to actively remove the carbon dioxide (CO2) already released into the atmosphere. At the same time, significant uncertainty remains about how much these carbon dioxide removal technologies can realistically contribute to the effort.
CO2 removal is something natural ecosystems – such as oceans, healthy forests, and wetlands – already do remarkably well, and preserving them is clearly in our own interest. However, experts also suggest that carbon dioxide removal (CDR) technologies will be necessary to adhere to the Paris Agreement’s target of keeping global warming well below 2°C and ideally 1.5°C, in order to avoid a future where many climate impacts cannot be reversed, leading to a much more dangerous, unstable, and costly world.
What are these technologies? “Carbon dioxide capture technologies are chemical processes which allow capturing CO2 from industrial sources or energy production. CO2 can also be captured directly from the atmosphere,” says expert Kati Koponen. Koponen, senior scientist at VTT Technical Research Centre of Finland, is among the authors of a report commissioned by the European Parliament’s Committee on Industry, Research and Energy on the role of Direct Air Capture (DAC).
Kati Koponen, senior scientist at VTT Technical Research Centre of Finland: “If CO2 is captured directly from the atmosphere or from bioenergy production and stored permanently, so-called permanent carbon dioxide removals, or negative emissions, can be created. Permanent carbon dioxide removals are needed to supplement drastic emission reductions and natural carbon sinks in forests and soils, to achieve Paris agreements targets for climate change mitigation.” – Read the full interview with Kati Koponen
There are multiple ways to remove carbon dioxide from the atmosphere, and several terms are often used interchangeably. “We can capture CO2 from coal-fired power plants, for example, thereby preventing that CO2 enters the atmosphere. The captured CO2 is then compressed, transported, and stored in underground geological formations. In this case we speak of Carbon Capture and Storage (CCS),” explains Sabine Fuss, a climate economist at the Potsdam Institute of Climate Research Impact.
After CO2 is captured, it needs to be stored and the role of different technologies for climate change mitigation varies. “If fossil CO2 is captured and stored permanently in geological formations, emission reductions can be achieved,” says Kati Koponen.
The durability of this storage is very important, warns Fuss: “While properly selected and managed sites of geological storage are generally considered to store CO2 for thousands to millions of years, additionally grown trees (afforestation) may release their CO2 much sooner, if they fall victim to either deforestation or to increasing disturbances from climate change such as wildfires or pests.”
Mineralising CO₂ in rocks is considered a reliable way to store it permanently, but CO₂ can also be utilised as a raw material for products – the ‘U’ in Carbon Capture Utilisation and Storage (CCUS). In such cases the removal may be only temporary. “If the CO2 is not permanently bound in the product, as for example in the case of synthetic fuels, emissions may be avoided, but not removed,” notes Fuss. “Furthermore, the capacity to store CO2 permanently in geological formations is still very limited and should be rapidly scaled up,” adds Koponen.
Sabine Fuss, climate economist at the Potsdam Institute of Climate Research Impact: “Each method to manage or remove CO2 comes with its own trade-offs and synergies and there is no single silver bullet we can rely on. Rather, we need to explore portfolios of methods realising the required removal potentials at minimal risks.” – Read the full interview with Sabine Fuss
High costs
Atmospheric carbon dioxide is a tricky molecule to manage: its concentration is high enough to drive global warming, yet too low to make direct air capture an easy task. Although removal technologies have already been piloted, “it is uncertain whether they can be scaled up to industrial scale for removals of dozens or hundreds of megatons of CO2 per year from the atmosphere” says Kati Koponen. The main limitations include high costs, significant energy requirements, and related sustainability challenges.
“The key limitation for direct air capture and storage (DACCS) technologies is the significant energy consumption: as CO2 in the atmosphere is in very low concentrations, significant amounts of energy is needed to capture it” says Kati Koponen. “Scaling DACCS obviously only makes sense based on a sufficiently decarbonised energy system” adds Sabine Fuss. In addition to demanding more critical minerals to build dedicated solar and wind capacity, increasing green energy use from the grid could divert electricity from other civil uses.
“The technology also currently has very high costs” says Koponen. Despite limited data and the scarcity of comprehensive techno-economic assessments, the report she co-authored for the European Parliament estimates that costs for First-of-a-Kind DACCS plants range from 200 to 900 €/ton CO2 captured.
Planning to reduce net emissions by 90% by 2040 in the EU, industrial carbon removals such as DACCS are expected to scale up significantly.. According to the report for the EP mentioned above, achieving 40 megaton (Mt) of DACCS removals by 2040 (even with investments halving costs through research and scale) would still require an estimated €12–24 billion.
At present, global CO₂ removals from DACCS and bioenergy production with carbon capture amount to only about 0.5 Mt of CO₂.
Not consistently rewarded
Another key factor for scaling up is incentivising CO2 removal. “While the emission of CO2 is being penalised by requiring facilities to surrender or buy permits for each ton emitted, the removal of CO2 from the atmosphere is currently not consistently rewarded” notes Sabine Fuss. She also highlights additional obstacles in other domains, including the legal situation of CO2 transport and storage in some EU countries, the low level of public acceptance that also differs across countries, and high up-front costs in the face of investment uncertainty.
Taken together, these factors point in the same direction: carbon dioxide removal (CDR) and carbon capture and storage and utilisation technologies still have a long way to go before they can be considered fully reliable tools in the fight against climate change.
Relying solely on afforestation and reforestation, however, could also be risky, because “conventional removals are often much more vulnerable to reversal or may become less effective under climate change,” says Sabine Fuss. These limitations, however, do not justify a default stance of techno-optimism: “Scarce CDR potentials should not be squandered on offsetting emissions that can be cost-effectively dealt with in other ways” states Sabine Fuss.
Carbon capture: a way to continue business as usual
Carbon capture technologies have often been promoted by the fossil fuel industry as a way to continue business as usual – burning natural gas, oil, and coal – while claiming climate responsibility.
Careful scrutiny will be indispensable in this context: “Recent research shows that the oil and gas sectors’ plans to scale CDR remain rather vague, which is why it is important to scrutinise such claims of climate responsibility in detail” points out Sabine Fuss. “In particular, removals need to be additional, take into account issues around permanence including the risk of reversal, be based on atmospheric or biogenic CO2, feature transparent, science-based, and third-party verified monitoring, reporting and verification, minimise leakage and respect other dimensions of sustainability.”
With such a comprehensive approach, Europe is well positioned to play its part. “The Commission has established the so called CRCF framework for the voluntary certification of the carbon dioxide removals. During the year 2026, the inclusion of BECCS and DACCS in the European Emission Trading System will be discussed” says Kati Koponen. She notes that separate targets for permanent carbon dioxide removals, along with dedicated support schemes or purchase programs, will likely be needed to help scale up the technologies.
“With a strong profile in research and development and a responsibility in terms of having accumulated a significant portion of the emissions currently in the atmosphere, Europe would be well-placed to promote the advancement of novel CDR. Arguments beyond these also include the prospects of technological leadership, avoided or reduced climate impacts during a hopefully lower and shorter period of overshoot, and more flexibility in the context of carbon management” concludes Sabine Fuss.
Related content:
• A scientist’s opinion: interview with Sabine Fuss on removing carbon dioxide from the atmosphere
• A scientist’s opinion: interview with Kati Koponen on removing carbon dioxide from the atmosphere