written by Raphaël Cario
Introduction
In response to the climate crisis, theParis Agreement, adopted in 2015, sets crucial targets for limiting global temperature rise to below 2°C above pre-industrial levels, with an ideal target of 1.5°C. However, despite more than three decades of warnings about global warming, government efforts to reduce CO2 emissions have only recently begun to intensify. Time is running out, and the window for action is dramatically shortening. Ratified by the European Union (EU) and its member states in 2016, the Paris Agreement is the first legally binding agreement on climate change with universal reach. The EU and France have pledged to limit the rise in global temperature and greenhouse gas emissions. climate laws The resulting agreements set targets for carbon neutrality by 2050. On a global scale, however, emissions of greenhouse gas emissions have continued to rise. With 2% of growth in 2023, they will exceed 40 Gt of total emissions.
Achieving carbon neutrality within the next 25 years is unattainable if we limit ourselves to emissions reductions alone. While this remains the priority, the transition to negative net emissions requires an exponential acceleration of efforts, and carbon dioxide removal (CDR) is becoming indispensable. But beyond neutralizing residual emissions, CDR will play a key role in many aspects of the transition.
"Deploying carbon dioxide removal (CDR) technologies to offset hard-to-reduce residual emissions is a must if we are to achieve net CO2 or GHG emissions."
IPCC, Sixth Assessment Report
The roles of the CDR in Net-Zero
The Intergovernmental Panel on Climate Change (IPCC) insists on the fact that the place of CDR is necessary if we are to achieve carbon neutrality by 2050. The 2018 report presents four scenarios and explains that "[all] analyzed scenarios limiting warming to 1.5°C with little or no overshoot use CDR to neutralize emissions from sources for which no mitigation measures have been identified and, in most cases, to achieve negative net emissions to reduce warming to 1.5°C after a peak."
Residual Emissions Challenges
The CDR is essential to achieving carbon neutrality, which goes beyond simply reducing emissions. It's about achieving a balance where the last emissions are offset by equivalent absorptions to create a sustainable system. Thus, unavoidable emissions will have to be offset by other activities, leaving a crucial place for the CDR to balance residual emissions. The faster we aim to achieve neutrality, the more certain sectors will not have developed the technical solutions for their complete decarbonization, thus increasing the need for CDR.
There are reasons for residual emissions. Often, the absence of technical or economic solutions makes it difficult to completely decarbonize certain sectors. For example, construction today accounts for 21% of global emissions, and steel and cement production for have no obvious solutions decarbonation. Hydrogen that could be used in cement plants requires infrastructure still insufficient. By 2050, many sectors will not be ready for complete decarbonization, but neutrality is urgently needed to avoid a climate point of no return. By 2024, International Renewable Energy Agency (IRENA) established that sectors with residual emissions represent 20% of current emissions. The IPCC predicts that by 2050, nearly 10% of current emissions will remain. CDR would help to offset these residual emissions.
Temporary overshoot of 1.5°C and Net-negativity
In addition to these residual emissions, the CDR can limit warming overruns and continue to remove carbon beyond 2050. If global temperatures temporarily exceed 1.5°C, CDR will be needed to reduce atmospheric CO2 concentration and bring global temperatures back to safe levels.
To achieve this, the amount of CO2 removed from the atmosphere will have to be greater than that emitted, leading to a stage of "net negative emissions". This Net-negative will rectify any historical excess of CO2 that is still contributing to climate change and mitigate its effects. The larger and longer the excess, the greater the dependence on CDR practices to remove CO2 from the atmosphere.
As the Sir David King, former Chief Scientific Adviser to the British Government: "The IPCC does not go far enough on the CDR. I think it is more than likely that we will reach 1.5°C by the end of the decade. It's a fallacy to think that the IPCC says we can manage [to stay below that level] simply by cutting emissions. The carbon we have already emitted into the atmosphere will have to be removed."
CDR and related benefits
Beyond the goal of carbon neutrality, CDR offers co-benefits for mitigating the climate crisis. According to the IPCC, "CDR methods can deliver a range of benefits depending on the deployment scenario, while requiring appropriate governance to minimize undesirable side effects". For example, restoring forests or mangroves can also protect against floods and storms. A meta-analysis on biochar explains that it improves food security and sustainability by enhancing soil fertility and structure, as well as nutrient and water retention. It concludes an increase in plant productivity (+16%) and crop yields (+13%). Biochar also reduces greenhouse gas emissions (-11%) and heavy metal uptake by plants (-29%).
New CDR methods, such as geological carbon storage, offer superior storage durability to conventional earth-based methods, locking in carbon removals for hundreds to thousands of years. For example, the biochar and theforced weathering of rocks can improve soil health and agricultural yields, reducing the effects of drought. Improving the alkalinity of the oceans could protecting coral reefs and shellfish ocean acidification
Quantifying CDR needs
All IPCC scenarios limiting warming to 1.5°C with little or no overshoot project the use of CDR to the tune of 100 to 1000 GtCO2 over the 21st century. CDR would be used to offset residual emissions and, in most cases, to achieve negative net emissions in order to reduce warming to 1.5°C after a peak.
According to the report annual The State of CDR published by SWP and Oxford University, CDR deployment will be 7 to 9 GtCO2 per year in 2050. The lowest scenarios reach 4 GtCO2 per year in 2050. The most sustainable scenarios accumulate 170 GtCO2 between 2020 and the moment of carbon neutrality, compared with 260 GtCO2 in all scenarios below 2°C.
Which CDR technologies are used in the scenarios?
The climate scenarios are based on a diversified portfolio of CDR technologies, integrating both nature-based solutions (afforestation, reforestation) and technological solutions (DAC, ocean removal, biochar). This integrated approach will be essential, as no single technology can achieve these objectives on its own.
Scenarios pave the way for portfolio strategies. We need to promote various CDR technologies and their large-scale deployment to reduce costs. Highly uncertain price trends for these technologies mean that volume projections are varied, but with very high potential.
CDR in France and Europe
France and the European Union are beginning to include CDR in their carbon neutrality objectives. In France, the National Low-Carbon Strategy (SNBC2) provides for the management of residual emissions, estimated at 80 million tonnes of CO2 equivalent (MtCO2) by 2050, divided between ~30 MtCO2 of fossil origin and ~50 MtCO2 of biogenic origin. Natural sinks and the CDR will have to compensate for around 70 MtCO2/year to meet the goal of carbon neutrality by 2050 (see the projections from CarbonGap, a member of AFEN, which establish different distribution scenarios).
At European level, the EU plans that around 400 MtCO2 of residual emissions will need to be offset by CDR, encompassing both land-based and industrial solutions by 2050.
CDR dependency and Deployment dip
The longer we delay reducing emissions, the more dependent we become on the CDR to achieve carbon neutrality and mitigate climate effects. The European Academies of Sciences (EASAC) underline that these reductions must be accompanied now by the development of CDR capacities. If we delay in implementing them, they will become increasingly dependent on CDR to prevent us from reaching climatic points of no return.
This risk of dependence is exacerbated by the "deployment trough" observed in the CDR. Climate scenarios show a significant gap between the amount of CDR needed to meet the Paris Agreement targets and that proposed in national plans. According to The State of CDR, this gap could reach 0.9 to 2.8 GtCO2 per year in 2030, and 0.4 to 5.4 GtCO2 per year in 2050.
The real gap is probably greater, as climate scenarios assume significant emissions reductions that have yet to materialize, while global emissions continue to rise. To catch up, our reduction and CDR targets could increase by 1.5 GtCO2 per year by 2050 according to The State of CDR, calling for faster and more ambitious deployment of CDR. However, there are limits to CDR's ability to compensate for insufficient efforts to reduce emissions, underlining the need for immediate and reinforced action in emissions reduction alongside the deployment of CDR technologies.
Conclusion
The role of CDR in achieving carbon neutrality is essential. It enables us to compensate for unavoidable residual emissions, and to go beyond mere emissions reduction to achieve negative net emissions. To achieve these objectives, AFEN was launched this year to help bridge the investment gap, particularly in France, in a sector that is central and must be developed if we are to achieve carbon neutrality. However, the CDR is no substitute for a rapid and significant reduction in greenhouse gas emissions. Moreover, ambitious public policies and clear regulatory frameworks are essential to encourage the widespread adoption of CDR technologies. To achieve the global climate targets set by the Paris Agreement, it is essential to combine ambitious emissions reductions with immediate deployment of CDR techniques.
