On other occasions I have referred to the threat of unilateral deployment as being largely a myth that fails to take into account basic technical and political attributes of climate interventions such as stratospheric aerosol injection (SAI). Rather than restate my argument in full, I reproduce here a summary statement taken from a previously published article:*
Thus, the incentive structure faced by a state interested in implementing SAI would strongly discourage unilateral postures that dismissed the need for international agreement and coordination. Any country considering unilateral deployment would find itself tangled in a web of technical and political constraints and steered toward reaching some form of global consensus. Individual incentives may be inadequate to deter unilateralism on their own, but their collective weight is likely to tilt the playing field decisively in favor of multilateral cooperation. For instance, Country B may be sufficiently motivated to accept the costs associated with the termination problem and dispense with efforts to synchronize emissions mitigation policies. But once deployed, a large number of international actors would effectively exercise joint control over any injection system, frustrating any attempt by Country B to pursue a coherent SAI policy managed solely by its national government. Furthermore, any actor opposed to the project could easily (and anonymously) counter its effects using relatively simple means such as release of black carbon, thereby neutralizing the entire scheme. For Country B, the costs of unilateral SAI would exceed the benefits, due to the technical limitations inherent in unilateral deployment of such technology, and as a consequence, interest in SAI would require a multilateral approach. The net result is that states are unlikely to view unilateral deployment as a sound, effective policy option. (p. 62)
Perhaps WEF will reconsider designating unilateral deployment as an "X Factor" and stop inadvertently lending support to the more obstinate and unreasonable among geoengineering's critics. Alas, probably not.
*Joshua B. Horton, "Geoengineering and the Myth of Unilateralism: Pressures and Prospects for International Cooperation," Stanford Journal of Law, Science & Policy 4 (2011): 56-69