Determining our climate policy future: expert opinions about negative emissions and solar radiation management pathways

Abstract

Negative emissions technologies and solar radiation management techniques could contribute towards climate stability, either by removing carbon dioxide from the atmosphere and storing it permanently or reflecting sunlight away from the atmosphere. Despite concerns about them, such options are increasingly being discussed as crucial complements to traditional climate change mitigation and adaptation. Expectations around negative emissions and solar radiation management and their associated risks and costs shape public and private discussions of how society deals with the climate crisis. In this study, we rely on a large expert survey (N = 74) to critically examine the future potential of both negative emission options (e.g., carbon dioxide removal) and solar radiation management techniques. We designed a survey process that asked a pool of prominent experts questions about (i) the necessity of adopting negative emissions or solar radiation management options, (ii) the desirability of such options when ranked against each other, (iii) estimations of future efficacy in terms of temperature reductions achieved or gigatons of carbon removed, (iv) expectations about future scaling, commercialization, and deployment targets, and (v) potential risks and barriers. Unlike other elicitation processes where experts are more positive or have high expectations about novel options, our results are more critical and cautionary. We find that some options (notably afforestation and reforestation, ecosystem restoration, and soil carbon sequestration) are envisioned frequently as necessary, desirable, feasible, and affordable, with minimal risks and barriers (compared to other options). This contrasts with other options envisaged as unnecessary risky or costly, notably ocean alkalization or fertilization, space-based reflectors, high-altitude sunshades, and albedo management via clouds. Moreover, only the options of afforestation and reforestation and soil carbon sequestration are expected to be widely deployed before 2035, which raise very real concerns about climate and energy policy in the near- to mid-term.

A Contemporary Review on Geo-engineering Techniques for Mitigation of Accelerated Rise in Global Sea Level in the Past Eight Hottest Years

“…According to ongoing research, some, if not all, of these strategies could constitute an important tool-kit for climate intervention or a climate barrier [18]. Furthermore, these strategies have the practical advantage of not requiring complex planning at land and also avoids direct changes to the atmosphere.…”

Coral reefs, cloud forests and radical climate interventions in Australia’s Wet Tropics and Great Barrier Reef

“…But it is further off in terms of development, possibly ten years away. Lending support to this claim, one recent expert survey of geoengineering found a consensus that marine cloud brightening would not be broadly deployable until 2040 [19].…”

“…Within the discourse on climate interventions and pathways, typologies and distinctions abound, notably, between the aims of mitigation from adaptation and "geoengineering" approaches [13], and around the need for split consideration of carbon removal vis-à-vis solar geoengineering [14,15]. Other studies draw important distinctions between "natural" carbon removal options versus "chemical" or "engineered" options [16][17][18][19]. Still other work distinguishes between "hard," centralized, scale-driven approaches versus "soft," distributed, bespoke approaches [20].…”

Scaling carbon removal systems: deploying direct air capture amidst Canada’s low-carbon transition

“…In effect, these recommendations seek to close the current incentive gap by encouraging policymakers to directly support innovation financially and to introduce measures to ensure transparency and diffusion of information on CDR throughout society, thereby reducing uncertainty in the system. Sovacool et al (2022), drawing on a large number (n = 125) of expert interviews identify a set of 10 DAC-specific policy recommendations. In line with earlier studies, Sovacool et al emphasize the importance of using DACCS to lower the stock of atmospheric emissions, not as a substitute for reducing emissions and climate adaptation (see also Beuttler et al, 2019;McLaren et al, 2019;Erans et al, 2022), as well as the need to prioritize long term storage and to leverage emerging carbon capture and storage infrastructure.…”

“…In line with earlier studies, Sovacool et al emphasize the importance of using DACCS to lower the stock of atmospheric emissions, not as a substitute for reducing emissions and climate adaptation (see also Beuttler et al, 2019;McLaren et al, 2019;Erans et al, 2022), as well as the need to prioritize long term storage and to leverage emerging carbon capture and storage infrastructure. The social dimensions of DACCS have received increasing attention from both instrumental (acceptability) and non-instrumental (justice and legitimacy) perspectives, with recommendations directed toward procedural conditions, such as transparency and stakeholder participation, and substantive outcomes, such as the distribution of benefits and impacts of DACCS (Buck, 2016;Pozo et al, 2020;Sovacool et al, 2022;Satterfield et al, 2023). Overall, the literature underlines the importance of introducing policy instruments to create incentives for investing and scaling up DACCS, such as carbon pricing; decarbonization policy; CDR-specific targets and tax credits; research and development subsidies for NETs and carbon utilization; carbon offset and trading protocols; and clear regulations around carbon storage and transport (Creutzig et al, 2019;Fajardy et al, 2019;McLaren et al, 2019;Honegger et al, 2021;Meckling and Biber, 2021).…”