Carbon dioxide removal (CDR) in no doubt is an irreplaceable part of climate actions at different levels. In the near term, CDR will contribute to mitigation efforts, even though the magnitude of its impact is not as great as of emissions reductions. However, at the net-zero, or even net-negative, stages, CDR will play an essential role in offsetting the hard-to-abate residual emissions. Considering the likely unavoidable temperature overshoot, the rapid and large-scale deployment of CDR seems to be becoming a default setting in many scenarios of mitigation pathways, globally and nationally. However, there is a growing voice in the climate community that there should be more caution when considering the role of CDR in the portfolio of climate actions. Researchers, policymakers and civil society are starting to raise various concerns about its feasibility and risks1.

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One fundamental concern is whether CDR can be scaled sufficiently in the real world. When projecting mitigation pathways for different climate targets at different timescales, including temperature control or net-zero emissions, fast and large-scale CDR deployment is often included. CDR became a dominant part of emissions scenarios from the 2000s and was seen as an urgent priority. However, so far, the needed scaling-up is still lacking in the real world. Furthermore, existing CDR almost all comes from afforestation. Novel CDR methods, such as bioenergy with carbon capture and storage (BECCS) and direct air capture with carbon storage (DACCS), are all still immature for large-scale application given their technical and economical limitations2. It has been suggested that CDR would replicate the success of wind and solar in the past decade, but the validity of such assumptions remains in doubt.

There are concerns that rather than being an effective way to reduce emissions, CDR is diverting attention and efforts from the urgent actions needed now, such as fossil-fuel phase-out3. There is also concern about the ‘moral hazard’ issue — that planned CDR will give the impression to policymakers and the public that it is fine to keep burning fossil fuels now because the emissions will be offset eventually. This has potential disastrous outcomes, as the risks of delayed action are high and irreversible for humans. CDR should not be seen as an escape route.

Even if it is feasible to deploy large-scale CDR, the related negative environmental impacts on the Sustainable Development Goals (SDGs) should not be ignored. However, currently, these are not fully considered in policymaking processes. Poorly designed CDR options could lead to problems such as land-use conflicts, energy or water overconsumption, and increased health burdens, to name a few4. Thus, rather than simply looking at the dimension of carbon removal, broader aspects of environmental trade-offs should be assessed under an integrated framework when estimating CDR potential5.

Lastly, consistency across different levels of policy settings needs to be carefully checked. Writing in this issue of Nature Climate Change, Lamb and colleagues identify that current national proposals do not fully align with the target of limiting warming to 1.5 °C, the ‘CDR gap’. Only the most ambitious proposals of CDR are close to a low-energy-demand scenario generated from integrated assessment models. The support for novel CDR methods is still lacking in many countries’ proposals. The accompanying Policy Brief further unpacks the key messages for policymakers, one of which is that the dependency on CDR should be minimized.

As we are all aware, the window of opportunity for climate action is closing. More balanced, realistic and comprehensive examination of CDR is necessary before its role in mitigation is further considered, which requires close collaboration between researchers, governments, the private sector and civil society across the world.