Joule
Volume 5, Issue 8, 18 August 2021, Pages 1956-1970
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Perspective
Cutting through the noise on negative emissions

https://doi.org/10.1016/j.joule.2021.06.013Get rights and content
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Context & scale

What role should negative-emission technologies (NETs) play in supporting global climate change mitigation? This is a polarizing question in both academic circles and increasingly public discourse. A common argument is that NETs present a risky or high-stakes gamble to climate change mitigation.

In this paper, we challenge this opposition to NETs. We show how this opposition is largely based on the results of integrated assessment models, which are the models that form the basis of IPCC reports. These models often show that a late-century, large-scale deployment of NETs is required to stabilize global warming to at or below 2°C this century. However, models are not real life, and such long-range forecasts are fraught with limitations. As a result, this is not a firm foundation for opposition. We make the case for place-based, bottom-up approaches for assessing the potential role for NETs in mitigation portfolios. Bottom-up approaches reveal the many ways in which NETs could (or could not) provide value to enhance economy-wide energy transition feasibility, such as through social and environmental co-benefits. For example, California has highly favorable attributes for NETs deployment. While applied to NETs, our findings more broadly suggest that more circumspect approaches are needed regarding the use of global models to inform mitigation pathways and strategies at jurisdictional scales.

Summary

Negative-emission technologies (NETs) are widely viewed as a risky backstop technology for climate change mitigation. In this perspective, we challenge this limited view of NETs. We show how, notwithstanding their merit, integrated assessment models (IAMs) are largely responsible for establishing this opposition to NETs. This is because IAM-based assessments of NETs dominate the policy-facing literature, but as a result of model limitations, we are left with a deceptively shallow understanding of the role NETs could play to support long-term mitigation goals. Therefore, in the second part of this perspective, we provide a non-IAM-based fresh take on NETs. We explore NETs via a bottom-up analysis and introduce a decision-making framework to determine the circumstances under which NETs could provide value as a mitigation option at jurisdictional scales. We apply this framework to case studies in California and New Mexico, highlighting how NETs could overcome socio-technical obstacles and unlock a variety of environmental and social co-benefits as part of helping to achieve time-bound mitigation goals. Overall, this perspective aims to cut through what we see as a noisy discourse on NETs, which is wrapped-up in concerns that are dependent on scenario modeling and offer a plain evaluation of NETs as a potential climate change mitigation option.

Keywords

climate mitigation
negative emissions
integrated assessment models
socio-technical
bioenergy
CCUS

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