Confronting mitigation deterrence in low-carbon scenarios

Choices concerning the levels and timing of mitigation in low-carbon scenarios are sensitive to how much carbon dioxide removal (CDR) can be deployed in the future. There is a growing concern about mitigation deterrence: the risk that anticipated future CDR could dilute incentives to reduce emissions now. This article describes the use of an integrated assessment model (IAM) to analyse this relationship between emission reduction and emission removal. The article points out that many studies operate under the implicit assumptions that emissions reduction and removals are perfect substitutes and that future CDR availability is known with certainty. This article challenges these assumptions given the uncertainty associated with CDR. The IAM modelling shows that explicitly incorporating uncertainty in CDR availability provides a strong rationale for increasing near-term emission reductions. For example, a 20% chance of CDR deployment failure requires additional emissions reduction in 2030 of 3–17 GtCO2. This finding underscores the importance of increasing near-term mitigation efforts.  

The article also incorporated new scenarios into the IAM that demonstrated the danger of mitigation deterrence and the benefit of separating CDR and emission reduction as climate strategies. The analysis finds that if mitigation deterrence persists (near-term mitigation is limited), global warming could overshoot the 1.5°C goal by up to 0.3°C. In the event of mitigation deterrence followed by CDR deployment failures, the outcome would worsen, putting the temperature goal of 1.5°C out of reach or substantially increasing the cost of achieving this goal. One effective way to avoid mitigation deterrence is to separate CDR and emission reduction as distinct strategies. The IAM shows that avoiding mitigation deterrence by first focusing on emission reductions, and then introducing CDR as an additional strategy to emission reduction, could help limit global warming to below 1.5°C by the end of the century.   

This article can be used to caution against optimism about future emission-removal technologies and advocate for stronger efforts to reduce emissions now. This is particularly pertinent in the case of fossil fuel production, since proponents often argue for expanded production based on scenarios that assume high levels of CDR.