Will engineered carbon removal solve the climate crisis?

(Nanowerk News) Meeting the 1.5°C target of the Paris Agreement will require ambitious climate action this decade. There are still hard questions about how heating can be limited within technical realities while respecting the shared but different responsibilities and capabilities of individual countries on the journey towards a sustainable future. Meeting this challenge requires substantial emission reductions to achieve net-zero emissions globally.

Among the new options studied in the scientific literature, engineered Carbon Dioxide Removal (CDR) such as Direct Air Capture of CO2 with Carbon Capture and Storage (DACCS), is a potentially promising technology to help bridge this gap. DACCS captures carbon by passing ambient air over a chemical solvent, which can be considered a form of CDR if the captured carbon is permanently stored underground. But whether these new technologies can help make ambitious goals more achievable, or whether they can help achieve them more equitably is still an open question.

In their study published in Environmental Research Letter (“Fairness and feasibility in a deep mitigation pathway with new carbon dioxide removals taking into account institutional capacity for mitigation”), an interdisciplinary research group led by IIASA scientists developed new scenarios exploring fairness and feasibility in deep mitigation pathways, including new CDR technologies. For the first time, the team applied DACCS in a well-established integrated assessment model called MESSAGEix-GLOBIOM, and studied how this technology could influence global mitigation pathways under various environmental policy effectiveness scenarios based on country-level governance indicators.

“In current policy debates, concerns about the political feasibility and fairness of current generation climate mitigation scenarios are raised, and DACCS is frequently proposed as a possible solution. In our research, we measure under what conditions and how DACCS can tackle the problem,” explained Elina Brutschin, study co-author and researcher in the Transformative Institutional and Social Solutions Research Group of IIASA’s Energy, Climate and Environment Program.

The researchers emphasize that the goal of limiting warming to 1.5°C does not change when considering new forms of CDR. For a broader perspective on pathways to limit warming, the research team investigates how the novel CDR interacts under assumptions of different technoeconomic advances and the evolution of regional institutional capacities. The researchers highlight the risks of reliance on unproven removal of carbon while also discussing the new role CDR and similar technologies could play in the future for developing countries.

The results suggest that the new CDR can keep pre-Paris climate targets within reach when taking those risks into account, but institutional capacity building beyond historical trends is needed to limit warming to the Paris Agreement goal of 1.5°C, even with the new CDR process. The study also shows that substantially increasing institutional capacity to implement environmental policies, regulations and laws is critical to keeping warming below 2°C if new forms of CDR fail to emerge in the near future.

The authors further point out that, when taking into account the likely future evolution of the new CDR technology combined with the inherent risks, the ‘fairness’ of the overall outcome does not improve appreciably. DACCS does not affect the ambitions for short-term global mitigation needed, and additional removals in developed countries contribute only a fraction of the mitigation needed to achieve strict climate targets. This is because the area’s removal of carbon dioxide has not sufficiently offset its historic emissions by mid-century.

The inability of DACCS to increase the equity of outcomes, such as cumulative carbon emissions, in a 1.5 °C scenario, underscores the notion that meeting global climate targets is a global endeavor requiring an ‘all of the above’ mitigation strategy. There is no room for flexibility in achieving climate goals.

The results, however, suggest that engineered displacement may play a role in making the post-peak temperature stabilization (or lowering) phase more even. This means that the full time frame in which accounting is carried out is critical to exploring the equitable outcomes agreed to by most Parties to the United Nations Framework Convention on Climate Change (UNFCCC).

“Our results show that new technologies for removing carbon from the atmosphere can play a role in ambitious climate policies, but they will not be a silver bullet to solving the climate crisis. Developed countries especially need to reduce emissions over this half-decade, primarily by reducing existing emission sources while upgrading CDR technologies to be in line with the Paris Agreement,” said study lead author Matthew Gidden, a researcher at IIASA Energy. Climate, and Environmental Programs.

The researchers emphasize that there is a clear need for the modeling community to assess the role of the new CDR in a structured way to better understand robust results and insights versus observations tied to a particular modeling framework or approach. Going forward, these issues could be explicitly included in scenario designs to achieve more equitable outcomes while incorporating the political reality of the ability of governments and institutions to enact strong climate policies.