Decision-makers have confirmed the long term objective of preventing a temperature increase greater than 2 °C. This paper aims at appraising by means of a cost-benefit analysis whether decision makers’ commitment to meet the 2 °C objective is credible or not. Within the framework of a cost-benefit type integrated assessment model, we consider that the economy faces climate damages with a threshold at 2 °C. We run the model for a broad set of scenarios accounting for the diversity of “worldviews” in the climate debate. For a significant share of scenarios we observe that it is considered optimal to exceed the threshold. Among those “non-compliers” we discriminate ”involuntary non-compliers” who cannot avoid the exceedance due to physical constraint from ”deliberate compliers” for whom the exceedance results from a deliberate costs-benefit analysis. A second result is that the later mitigation efforts begin, the more difficult it becomes to prevent the exceedance. In particular, the number of ”deliberate non-compliers” dramatically increases if mitigation efforts do not start by 2020, and the influx of involuntary non-compliers become overwhelming f efforts are delayed to 2040. In light of these results we argue that the window of opportunity for reaching the 2 °C objective with a credible chance of success is rapidly closing during the present decade. Further delay in finding a climate agreement critically undermines the credibility of the objective.
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1 A comprehensive description is provided in supplementary material.
2 The climate externality does not enter into the utility function. It is only captured by a damage function.
3 Allowing for carbon dioxide removal (CDR) would alter our results, but to an extent unknown. We believe that it would only slightly modified them: when the constraint that abatement is below 1 is not binding, allowing for CDR (i.e. removing this constraint) does not change the optimal solution. For a significant set of solutions, the constraint is effectively non-binding (see e.g. the solution discussed in Section 4.1).
4 Comments following the (Stern 2006) Review (Dasgupta 2007; Nordhaus 2007; Weitzman 2007; Yohe and Tol 2007) have mainly emphazised the impact of the so-called unusually low rate of pure time preference of 0.1 % (which makes the discount rate used in Stern’s runs amount to 1.4 %) on Stern’s recommendation of early and strong mitigation action. In turn, the “policy ramp” promoted by Nordhaus (2008) would be driven by a more conventional level of pure time preference (2.8 %) leading to a discount rate of 4.1 %.
5 The precise formula of the SCC is provided in supplementary material.
6 The same analysis has also been carried out with temperature thresholds of 2.5 °C and 3 °C. We find the same type of results with however one or two decades of delay, depending on the temperature threshold (the higher the threshold, the later the occurrence of the non-compliers wave).
7 Transition matrix of this repartition is provided in supplementary material
Ambrosi P, Hourcade J, Hallegatte S, Lecocq F, Dumas P, Ha-Duong M (2003) Optimal control models and elicitation of attitudes towards climate damages. Environ Model Assess 8 (3): 133–147
Archer D, Brovkin V (2008) The millennial atmospheric lifetime of anthropogenic CO2. Clim Chang 90 (3): 283–297
Archer D, Eby M, Brovkin V, Ridgwell A, Cao L, Mikolajewicz U, Caldeira K, Matsumoto K, Munhoven G, Montenegro A, et al (2009) Atmospheric lifetime of fossil fuel carbon dioxide. Ann Rev Earth Planet Sci 37: 117–134
Cass D (1965) Optimum growth in an aggregative model of capital accumulation. Rev Econ Stud 32 (3): 233–240
Cointe B, Ravon P-A, Gurin E (2011) 2 °C: the history of a policy-science nexus. Working Papers IDDRI, n°19/11
Dasgupta P (2007) Commentary: the Stern review’s economics of climate change. Natl Inst Econ Rev 199 (1): 4–7
Davis S, Caldeira K, Matthews H (2010) Future CO2 emissions and climate change from existing energy infrastructure. Science 329 (5997): 1330–1333
Dietz T, Ostrom E, Stern P (2003) The struggle to govern the commons. Science 302 (5652): 1907–1912
Friedlingstein P, Cox P, Betts R, Bopp L, Von Bloh W, Brovkin V, Cadule P, Doney S, Eby M, Fung I, et al. (2006) Climate-carbon cycle feedback analysis: results from the c4mip model intercomparison. J Clim 19 (14): 3337–3353
Gitz V, Ciais P, et al. (2003) Amplifying effects of land-use change on future atmospheric co2 levels. Glob Biogeochem Cycles 17 (1): 1024–1029
Gjerde J, Grepperud S, Kverndokk S (1999) Optimal climate policy under the possibility of a catastrophe. Resour Energy Econ 21 (3): 289–317
Guivarch C, allegatte S (2012) 2 °C or not 2 °C? Glob Environ Chang 3 (1): 179 –192
IPCC (2007) Climate change 2007: mitigation. Contribution of working group III to the fourth assessment report of the intergovernmental panel on climate change. Cambridge University Press, Cambridge
Keller K, Bolker B, Bradford D (2004) Uncertain climate thresholds and optimal economic growth. J Environ Econ Manag 48 (1): 723–741
Keller K, Robinson A, Bradford D, Oppenheimer M (2007) The regrets of procrastination in climate policy. Environ Res Lett 2: 024004
Koopmans T (1963) Appendix to on the concept of optimal economic growth. Cowles Foundation Discussion Papers.
Lempert R, Groves D, Popper S, Bankes S (2006a) A general, analytic method for generating robust strategies and narrative scenarios. Manag Sci 52 (4): 514
Lempert R, Sanstad A, Schlesinger M (2006b) Multiple equilibria in a stochastic implementation of dice with abrupt climate change. Energy Econ 28 (5): 677–689
McInerney D, Keller K (2008) Economically optimal risk reduction strategies in the face of uncertain climate thresholds. Clim Chang 91 (1): 29–41
McInerney D, Lempert R, Keller K. (2009) What are robust strategies in the face of uncertain climate threshold responses Clim Chang: 1–22
Nordhaus W (1994) Managing the global commons: the economics of climate change. MIT Press, Cambridge. MA
Nordhaus W (2007) A Review of the Stern review on the economics of climate change. J Econ Lit 45 (3): 686–702
Nordhaus W (2008) A question of balance. Yale University Press
Nordhaus W, Boyer J (2003) Warming the world: economic models of global warming. the MIT Press
Ostrom E, Burger J, Field C., Norgaard R, Policansky D (1999) Revisiting the commons: local lessons, global challenges. Science 284 (5412): 278–282
Ramsey F (1928) A mathematical theory of saving. Econ J 38 (152): 543–559
Randalls S (2010) History of the 2 c climate target. Wiley Interdiscip Rev Clim Chang 1 (4): 598–605
Roe G, Baker M (2007) Why is climate sensitivity so unpredictable Science 318 (5850): 629
Rogelj J, McCollum D L, Reisinger A, Meinshausen M, Riahi K (2013) Probabilistic cost estimates for climate change mitigation. Nature 493 (7430): 79–83
Schneider S, Thompson S (1981) Atmospheric CO2 and climate: importance of the transient response. J Geophys Res 86 (C4): 3135–3147
Stern N (2006) The economics of climate change. The Stern review. Cambridge University Press
Tol R S J (2009) Climate feedbacks on the terrestrial biosphere and the economics of climate policy: an application of fund. Technical Report WP288, Economic and Social Research Institute (ESRI)
Weitzman M (2007) A review of the Stern review on the economics of climate change. J Econ Lit 45 (3): 703–724
Weitzman M (2009) On modeling and interpreting the economics of catastrophic climate change. Rev Econ Stat 91 (1): 1–19
Yohe G, Tol R (2007) The Stern Review: implications for climate change. Environ Sci Pol Sustain Dev 49 (2): 36–43
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Perrissin Fabert, B., Pottier, A., Espagne, E. et al. Why are climate policies of the present decade so crucial for keeping the 2 °C target credible?. Climatic Change 126, 337–349 (2014). https://doi.org/10.1007/s10584-014-1222-0
- Climate Policy
- Climate Sensitivity
- Abatement Cost
- Damage Function
- Social Planner