At this point it should be clear that quite apart from any scientific or technical issues there is a wide range of ethical issues to be solved before implementation of geoengineering would be acceptable from a moral point of view. Any number of these might prove decisive and it is far from obvious that all these moral requirements could today be satisfied. But let us assume they could be met, or that a climate catastrophe of such magnitude loomed that the requirements were loosened. Are there other ethical worries to consider that would emerge towards the end of a deployment?
If SRM is initiated then it is likely that, in the absence of any dramatic success in reducing emissions, greenhouse gases will continue to accumulate in the atmosphere even as planetary temperatures drop. Should any event—either geopolitical or climatic—make it necessary to cease SRM abruptly, temperatures would rise again very rapidly once the elevated level of carbon dioxide was unmasked. Though this ‘termination problem’ might hopefully be avoided through careful research of potential side-effects and through stable governance arrangements, the complexity of the climate system, the challenges raised by the limited ability to field test, and the perfect moral storm of climate change suggest that the scientific and political uncertainties about long-term deployment are likely to remain considerable.
In addition to the obvious danger for humanity, the termination problem would also threaten other species. While some species might be able to survive a sharp increase in temperature by migrating north (or upwards) or by adopting different behaviors, the chances of adaptation decrease dramatically as the rate of temperature change increases. Climate change is already a problem for many non-human species. The threat of abrupt termination of future SRM compounds this problem dramatically.
Sandler R. (2012). Solar radiation management and non-human species. In C. Preston (Ed.), Engineering the Climate: The Ethics of Solar Radiation Management (pp. 95-109). Lanham, MD: Lexington Press.
Svoboda, T., Keller, K., Goes, M., Tuana, N. (2011). Sulfate aerosol geoengineering: The question of justice. Public Affairs Quarterly, 25(3), 157–180.
Often described as a "lesser of two evils," geoeingeering is usually cast as a "temporary bridging mechanism" until such a time as greenhouse gas levels have been adequately reduced. Geoengineering may be capable of "buying some time" until adequate mitigation and/or adaptation measures have been put in place. It may not be easy, however, to determine when enough time has been bought and when the time is right to cease any geoengineering effort. With CDR, it would theoretically be possible to set a parts per million target for atmospheric carbon as a trigger point for cessation. Most forms of CDR would require considerable lengths of time to be effective and would also require emissions rates to be reduced close to zero. Climate inertia caused by the large heat capacity of the oceans may mean that even a ‘satisfactory’ atmospheric concentration of greenhouse gases would not necessarily indicate that temperatures were about to return to normal. Warmer temperatures and the dangers associated with them would likely be in store for many decades as the oceans slowly cooled. In the interim, some coupling of CDR and SRM may be necessary to temporarily reduce these temperatures.
If CDR is deployed on any scale, the distinction between removing carbon from the atmosphere and not emitting it in the first place may become blurry. At that point, CDR could become the favored mitigation strategy (over emissions reduction) and the idea of perpetual CDR could become attractive, forever changing the political calculus and creating a new 'normal.'
SRM presents the same questions about incentives for mitigation and adaptation but with an additional complicating factor: the already-accumulated carbon will be masked, not reduced. Not only would ocean acidification continue, but the termination problem would hover. The timescale over which carbon dioxide would be naturally re-absorbed into the world's oceans suggests that SRM would have to continue long into the future unless very large-scale CDR were also deployed.
Cessation of geoengineering technologies is clearly not as simple as hitting a temperature or ppm target and saying 'stop.' Decisions about the pathway toward emissions reduction and removal of any geoengineering technology would be contentious. Cessation would most likely require considerable progress on mitigation. The global community would face a complicated politics akin to the current challenges presented by climate change. While this politics may not prove impossible to navigate, the future of both SRM and CDR would always be woven both into each other and into ongoing mitigation and adaptation.
Ricke, K. L., Morgan, M. G., Allen, M. R. (2010). Regional climate response to solar–radiation management. Nature Geoscience 3, 537–541.
The fact that difficult choices would need to be made over when and how to cease geoengineering bleeds over into a different problem concerning the limits and possibilities of atmospheric design. The effects of climate change and any geoengineering efforts used to combat it will bring differentiated benefits and burdens in different regions. Under warming scenarios, Canadians, for example, may reap economic benefits from an ice-free Northwest Passage. Parts of Russia may be on track to become more suitable for growing crops with longer growing seasons. Conversely, dry regions would no doubt look forward to the benefits of increased precipitation if it could be reliably manufactured. We might find ourselves heading towards 'designer climates' where the whole idea of restoring a 'natural' climate has been abandoned entirely.
Szerszynski and Galarraga have discussed various lenses through which one might consider this work of 'making climate.' Because the climate is a constantly changing 'metastable' system, they suggest geoengineers would not be able simply to adjust one variable and then sit back and watch things unfold. More likely, continuous adjustments would be required in order to keep the climate heading where its manipulators wanted it to go. Galarraga and Szerszynski suggest that this forces those in control into a perpetual role of decision-making and creative engineering endeavor. To some extent, today's efforts at pollution control on marine diesel engines and coal-fired powerplants are already 'making climate.' Geoengineering would make the design questions much more explicit.
Galarraga, M., & Szerszynski, B. (2012). Making climates: Solar radiation management and the ethics of fabrication. In Preston, C. (Ed.), Engineering the Climate: The Ethics of Solar Radiation Management (pp. 221-236). Lanham, MD: Lexington Press.
Preston, C. J. (2012). Beyond the end of nature: Geoengineering and two tales of artificity for the anthropocene. Ethics, Policy, and Environment, 15(2), 188-201.