Eliciting Mental Models for Understanding Reasoning For and Against Solar Geoengineering Research

In this paper, the authors develop a fuzzy cognitive map based on the thinking of 10 experts on solar geoengineering.



May 30, 2023


Dale S. Rothman, Payam Aminpour, Ilan Chabay, and Jennifer Helgeson


Working Paper

Reading time

4 minutes


Solar geoengineering (SG) is a potential approach to reducing global climate change impacts by counteracting radiative forcing change driven by increased atmospheric concentration of greenhouse gases (GHGs). This negative radiative forcing can be produced in many ways, such as painting roofs white, modifying cloud properties, or installing mirrors in space. Stratospheric aerosol injection (SAI), where small reflecting particles are injected into the stratosphere, may be the most feasible and globally effective approach (NASEM 2012). This is also why it draws the most attention and stronger disagreements. SAI (henceforth SG) is the focus of this study. There has been no formal global debate on this topic, with discussions confined to conference and workshop meetings with limited international and sectoral representation.

Most people would agree that SG should not be deployed in the near term. The technology has not reached the stage where it can be seriously considered, and many fundamental questions, both technical and social, remain unanswered (NASEM 2012). However, a debate has arisen about whether we should even use resources to research SG. In the present study, we explore the latter question by examining expert reasoning concerning SG research.

Looking at information as a commodity that reduces uncertainty, economists would suggest that the value of any information is nonnegative. As such, using an extension of the widely used dynamic integrated assessment model of climate and economy (DICE), Harding et. al (2022) estimate that the value of information about the effectiveness of SG is as large as that about equilibrium climate sensitivity (Harding 2022). They also show that over- and underconfidence about SG are equally harmful. NASEM (2012) calls for cautious exploration of SG, which is a recurring theme in discussions of SG research, rooted in concerns around its procedural aspects and consequences.

Opposition to SG research takes various forms. Some opponents suggest that SG is either not needed or unacceptable under any circumstance, so research is unnecessary (Biermann 2021). A related concern, referred to as the “slippery slope,” states that research itself increases the likelihood of SG deployment. This is due, in part, to potential technological and institutional lock-in, whereby unnecessary and unwarranted deployment may emerge from research. Similarly, they suggest that research conducted largely by the Global North would only preserve current inequalities in the world (Stephens 2020) and further concentrate power among elites (Stephens and Surprise 2021). Perhaps the most common argument against SG research is the possibility that even research alone would reduce efforts toward emissions abatement (Stephens et al. 2021).

In the context of the ongoing climate crisis, proponents of SG research urge governments to evaluate all action options, including SG (Give Research into Solar Geoengineering a Chance 2021). They do share several of opponents’ concerns. Rather than forgoing research, however, they encourage capacity building in developing countries and argue for a responsible international program (Keith 2017). Others suggest that the research program should include safeguards to prevent unwarranted deployment, including explicit conditions under which deployment is justifiable (Jamieson 1996). As for deterring emissions abatement, the counterargument states that SG research may change the perception of how serious climate risks are, triggering an increase in emissions abatement. In addition, proponents suggest that even if emissions deterrence occurred, it would be characterized by increased overall welfare. Finally, proponents argue that a better understanding of not only the technical but also social, political, and economic aspects of SG may improve decisionmaking if, and when, deployment is ever considered. Suppressing SG research may not prevent future deployment but rather make it less informed and more dangerous (Parson 2021).

Both sides have some points of agreement, such as the importance of an international governance mechanism that is just and inclusive. However, expectations differ significantly. While many proponents believe international governance would emerge from multilateral agreements and informal scientific cooperation, many opponents argue that democratic and fair governance of SG is unattainable (NASEM 2012). Finally, not all opponents argue for an unconditional moratorium on research. Instead, they propose a set of conditions that must be satisfied. For example, Biermann and Möller (2019) suggest that developing countries should lead the discourse on SG research. Jamieson (1996) calls on the United Nations to govern SG research that otherwise may be militarized or securitized.

In a nutshell, both opponents and proponents share many concerns; however, they arise from different base assumptions and reasoning. In addition, both are typically driven by the principle of precaution, but their interpretations and conclusions diverge. This warrants an in-depth study of the underlying reasoning about SG research.

Another important caveat regarding the debate is the difference between in-lab and small-scale field SG research. By “in-lab research,” following Parson and Keith (2013), we mean computer simulations, chemistry experiments in controlled laboratories, and social and political science research. By “small-scale field research,” we mean activities with trivial and only local environmental impact that is smaller than common commercial activities. Thus, the debate is not just between opponents and proponents of SG research, but between three groups: (a) those who support both types of research, (b) those who support only in-lab research under current circumstances, and (c) those who oppose both types.

In the present paper, we extend the existing analyses of the arguments for and against SG research by having 10 experts complete a questionnaire, which is used to create a fuzzy cognitive map (FCM) of their thinking related to this topic. This is followed by an online interview, in which the initial maps are presented, discussed, refined, and “verified.” Our contributions are twofold. First, ours is the first study to employ fuzzy cognitive mapping to analyze attitudes toward SG research. Second, we explicitly distinguish and systematically compare attitudes toward in-lab and small-scale field research. Discussions concerning SG do not always consider these separately. In some cases, arguments are put forward for/against both in-lab and small-scale field research, although not stated so explicitly.

The remainder of the paper is organized as follows. The following section details our methodology. Section 3 presents (preliminary) results accompanied by a discussion.


Dale Rothman headshot.jpg

Dale S. Rothman

George Mason University

Payam Aminpour headshot

Payam Aminpour

Johns Hopkins University

Ilan Chabay headshot.jpg

Ilan Chabay

Arizona State University

Jennifer Helgeson.jpg

Jennifer Helgeson

Virginia Tech

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