On the Permissibility (Or Otherwise) of Negative Emissions

ABSTRACT

Limiting dangerous climate change is now widely believed to require negative emissions (NETs), a prospect some believe to be unjust and unacceptably risky. While NETs are not risk-free, I argue that they could be part of minimally just responses to climate change. In doing so, I identify a dilemma between limiting warming to 1.5 ° C, which promises lower climate impacts but implies greater NETs risks, and 2°C, which requires less NETs but promises greater climate impacts. Finally, I consider what the case of NETs reveals about permissibility in the face of non-compliance with principles of climate justice.

KEYWORDS:

• Climate justice
• negative emissions
• carbon dioxide removal
• geoengineering

Acknowledgments

I am grateful to Jan Minx and Sabine Fuss for my understanding of negative emissions, and especially to Henry Shue for discussion and comments upon an earlier draft. Remaining errors are my own. I also wish to thank participants at the European Consortium of Political Research in Oslo, 2017, and at the workshop on ‘Second-Best Solutions and Secondary Injustices’ at the University of Warwick, funded by the Leverhulme Trust.

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Notes

1. NETs are also known as Carbon Dioxide Removal (CDR).

2. Indeed, article 4.1 of the French language version of the Paris Agreement refers explicitly to achieving the desired balance of anthropogenic emissions and sinks. My thanks to Richard Millar for this point.

3. For detailed descriptions of each technique, see IPCC (2014), Ch. 6.

4. Several commentators believe this term to be misleading, preferring ‘risk compensation’ (Keith, 2013) or ‘mitigation obstruction’ (Betz & Cacean, 2012; Morrow, 2014).

5. I base my discussion upon the ‘Shared Socioeconomic Pathways’ (or SSPs), which are a recent development in the IAM literature and which look set to feature prominently in the IPCC’s Sixth Assessment Report.

6. See the Technical Summary in IPCC (2014).

7. See Steve Rayner (2010, p. 2620). Rayner, Tim Kruger, and Oliver Geden assert that the presence of NETs in the IPCC models is a piece of wishful thinking. See https://www.theguardian.com/science/political-science/2016/apr/26/abandon-hype-in-climate-models

8. For discussion of the potential of SRM to create a Sophie’s choice, see Gardiner (2010).

9. Many individual emissions scenarios are compatible with each SSP.

10. See Calvin et al. (2017).

11. Much smaller changes in the price and availability of food have separated a situation of peace and cooperation from one of starvation and discord. See Parker (2013).

12. See Van Vuuren et al. (2017).

13. See Fricko et al. (2017).

14. These assumptions are clearly stated in the SSP narratives.

15. The availability of SRM geoengineering opens further possibilities. Consider choosing between an ‘all of the above’ strategy including SRM technologies coupled with ambitious mitigation, and ‘all of the above’ following deferred mitigation.

16. See Peters and Geden (2017).

17. Anderson and Peters argue in favor of energy demand reductions via sustainable consumption. As we saw earlier, this would make a great difference to eventual NETs requirements.

18. Rogelj et al. (2015).

19. Although 2°C scenarios without NETs have similar bioenergy components, and thus similar land-use requirements. See Rose et al. (2014).

20. See Heyward and Roser (2016). According to Rawls (2003, p. 13), a situation is non-ideal when either of two basic conditions fail to obtain, namely full compliance with the principles of political morality, and favorable external circumstances.

21. Morrow and Svoboda adopt Wiens (2012) ‘clinical theory’ perspective, which aims to identify politically feasible institutions and policies that target injustice.

22. Although these must be gains of justice and not merely welfare.

23. Ironically, Morrow and Svoboda cite Shue’s (1993) well-known argument for ‘subsistence emissions’ in support for greater reliance upon NETs.

24. Kriegler et al. (2017).

25. See also Shue (2017, p. 209ff.). Of course, much depends upon where such thresholds actually are. If they are very low, then conventional mitigation also seems incompatible with avoiding crossing them, while if they are higher, NETs may indeed buy time until such thresholds are reached.

26. This is the view of the SSP authors themselves.

27. SSP4 and SSP5 have higher atmospheric concentrations than SSP3, but are still technically compatible with 2°C because of the greater policy coordination among nations. Nonetheless, SSP4 is presumed to be more unjust, envisaging worsening global inequality.