The 2°C Target Reconsidered

  • Brigitte KnopfEmail author
  • Martin Kowarsch
  • Christian Flachsland
  • Ottmar Edenhofer


While the 2°C target has become an important reference point in the international climate-policy arena, as stated for example in the Copenhagen Accord in 2009, its scientific underpinning and its legitimacy is heavily debated in the scientific community. In this chapter, outstanding experts in the field, representing opposing viewpoints within the scientific community, present their view on the 2°C target. While Mike Hulme casts doubt on the usefulness of the very idea of a specific temperature target as guidance for mitigation policy, Claus Leggewie and Dirk Messner claim that the 2°C target has an important instrumental value in the discourse surrounding climate-related risks. We discuss both contributions and argue that climate stabilisation goals provide a useful framework for a consistent discussion of climate policy choices. We point out that the 2°C objective has two major merits: first, as a global climate stabilisation goal it provides a useful framework around which to structure the global climate policy debate. Second, we consider it an appropriate climate policy goal enabling currently available scientific knowledge to be combined with some explicit value judgements. Nevertheless, further research and public debate are required to reduce uncertainties and substantiate this conjecture.


2°C target Article 2 Climate change and ethics Climate targets UNFCCC 


  1. Archer, D., & Rahmstorf, S. (2010). The climate crisis: An introductory guide to climate change. Cambridge: Cambridge University Press.Google Scholar
  2. Baer, P., & Spash, C. L. (2008). Cost-benefit analysis of climate change: Stern revisited (CSIRO Working Paper Series 2008–07). Canberra: CSIRO Sustainable Ecosystems.Google Scholar
  3. Caney, S. (2009). Justice and the distribution of greenhouse gas emissions. Journal of Global Ethics, 5(2), 125–146.CrossRefGoogle Scholar
  4. Clausen, L. (2010). Wohin mit den Klimakatastrophen? In H. Welzer & I. Schulze (Eds.), KlimaKulturen (pp. 97–110). Frankfurt: Campus Verlag.Google Scholar
  5. Dasgupta, P. (2007). Commentary: The Stern review’s economics of climate change. National Institute Economic Review, 199, 4–7.Google Scholar
  6. Edenhofer, O., & Kowarsch, M. (2012). A pragmatist approach to the science-policy interface (Working paper).Google Scholar
  7. Edenhofer, O., Knopf, B., Barker, T., Baumstark, L., Bellevrat, E., Chateau, B., Criqui, P., Isaac, M., Kitous, A., Kypreos, S., Leimbach, M., Lessmann, K., Magné, B., Scrieciu, S., Turton, H., & van Vuuren, D. P. (2010). The economics of low stabilization: Model comparison of mitigation strategies and costs. The Energy Journal, 31, 11–48 (Special issue 1).Google Scholar
  8. Hansen, J., Sato, M., Ruedy, R., Kharecha, P., Lacis, A., Miller, R., Nazarenko, L., Lo, K., Schmidt, G. A., Russell, G., Aleinov, I., Bauer, S., Baum, E., Cairns, B., Canuto, V., Chandler, M., Cheng, Y., Cohen, A., Del Genio, A., Falufegi, G., Fleming, E., Friend, A., Hall, T., Jackman, C., Jonas, J., Kelley, M., Kinag, N. Y., Koch, D., Labow, G., Lerner, J., Menon, S., Novakov, T., Oinas, V., Perlwitz, J., Perlwitz, Ju, Rind, D., Romanou, A., Schmunk, R., Shindell, D., Stone, P., Sun, S., Streets, D., Tausnev, N., Thresher, D., Unger, N., Yao, M., & Zhang, S. (2007). Dangerous human-made interference with climate: A GISS model study. Atmospheric Chemistry and Physics, 7, 2287–2312.CrossRefGoogle Scholar
  9. Heal, G. (2009). Climate change analysis: A meta-review and some suggestions for future research. Review of Environmental Economics and Policy, 3(1), 4–21.CrossRefGoogle Scholar
  10. Howes, S., Jotzo, F., Wyrwoll, P., Nordhaus, W. D., Stern, N., & Garnaut, R. (2011). The changing case for climate change mitigation (CCEP Working Paper 1107, July 2011). Canberra: Centre for Climate Economics & Policy.Google Scholar
  11. Jaeger, C. C., & Jaeger, J. (2010). Three views on two degrees (ECF-Working Paper 2, 2010). Potsdam: European Climate Forum.Google Scholar
  12. Kahan, D. (2010). Fixing the communications failure. Nature, 463, 296–297. doi: 10.1038/463296a.CrossRefGoogle Scholar
  13. Knopf, B., Luderer, G., & Edenhofer, O. (2011). Exploring the feasibility of low stabilisation targets. Wiley Interdisciplinary Reviews of Climate Change, 2, 617–626.CrossRefGoogle Scholar
  14. Latour, B. (1988). The pasteurization of France. Cambridge/London: Cambridge University Press.Google Scholar
  15. Latour, B. (2001). Das Parlament der Dinge. Frankfurt: Suhrkamp.Google Scholar
  16. Lenton, T. (2011). 2 °C or not 2 °C? That is the climate question. Nature, 473, 7. doi: 10.1038/473007a.CrossRefGoogle Scholar
  17. Lenton, T. M., Held, H., Kriegler, E., Hall, J. W., Lucht, W., Rahmstorf, S., & Schellnhuber, H. J. (2008). Tipping elements in the Earth’s climate system. Proceedings of the National Academy of Sciences, 105(6), 1786–1793.CrossRefGoogle Scholar
  18. Meinshausen, M., Meinshausen, N., Hare, W., Raper, S. C. B., Frieler, K., Knutti, R., Frame, D. J., & Allen, M. R. (2009). Greenhouse gas emission targets for limiting global warming to 2°C. Nature, 458(7242), 1158.CrossRefGoogle Scholar
  19. Messner, D., & Rahmstorf, S. (2010). Kipp-Punkte im Erdsystem und ihre Auswirkungen auf Weltpolitik und –wirtschaft. In T. Debiel, D. Messner, F. Nuscheler, & C. Ulbert (Eds.), Global trends 2010. Frankfurt: Fischer Verlag.Google Scholar
  20. Nordhaus, W. D. (2007). A review of the Stern review on the economics of global warming. Journal of Economic Literature, 45(3), 686–702.CrossRefGoogle Scholar
  21. Nordhaus, W. D. (2008). A question of balance. New Haven: Yale University Press.Google Scholar
  22. Nordhaus, W. D. (2010). Economic aspects of global warming in a post‐Copenhagen environment. Proceedings of the National Academy of Sciences, 107(26), 11721–11726.CrossRefGoogle Scholar
  23. Nordhaus, W. D., & Boyer, J. (1999). Warming the world: Economic models of global warming. Cambridge, MA: MIT Press.Google Scholar
  24. Oppenheimer, M. (2008). A physical science perspective on disaster: Through the prism of global warming. Social Research: An International Quarterly, 75(3), 659–668.Google Scholar
  25. Oppenheimer, M., & Petsonk, A. (2005). Article 2 of the UNFCCC: Historical origins, recent interpretations. Climatic Change, 73(3), 195–226.CrossRefGoogle Scholar
  26. Ostrom, E. (2010). Polycentric systems for coping with collective action and global environmental change. Global Environmental Change, 20(4), 550–557.CrossRefGoogle Scholar
  27. Pielke, R. A. J. (2007). The honest broker: Making sense of science in policy and politics. Cambridge: Cambridge University Press.CrossRefGoogle Scholar
  28. Randalls, S. (2010). History of the 2°C climate target. WIREs Climate Change, 1(4), 598–605.CrossRefGoogle Scholar
  29. Rogelj, J., Nabel, J., Chen, C., Hare, W., Markmann, K., Meinshausen, M., Schaeffer, M., Macey, K., & Hohne, N. (2010). Copenhagen accord pledges are paltry. Nature, 464, 1126–1128.CrossRefGoogle Scholar
  30. Schellnhuber, H. J. (Ed.). (2006). Avoiding dangerous climate change. Cambridge: Cambridge University Press.Google Scholar
  31. Shaw, C. (2010). Is the dangerous limits discourse dangerously limited? Blog contribution at Earthscan: Blogging for a sustainable future. From Accessed on 3 May 2012.
  32. Singer, S. F., & Avery, D. T. (2007). Unstoppable global warming: Every 1,500 years (Updated and expanded ed.). Lanham: Rowman and Littlefield.Google Scholar
  33. Smith, J. B., Schneider, S. H., Oppenheimer, M., Yohe, G. W., Hare, W., Mastrandrea, M. D., Patwardhan, A., Burton, I., Corfee-Morlot, J., Magadza, C. H. D., Füssel, H. M., Pittock, A. B., Rahman, A., Suarez, A., & Ypersele, J. P. (2009). Assessing dangerous climate change through an update of the Intergovernmental Panel on Climate Change (IPCC) “reasons for concern”. Proceedings of the National Academy of Sciences, 106(11), 4133–4137.CrossRefGoogle Scholar
  34. Star, S. L., & Griesemer, J. R. (1989). Institutional ecology, ‘translations’ and boundary objects: Amateurs and professionals in Berkeley’s Museum of Vertebrate Zoology, 1907–39. Social Studies of Science, 19(3), 387–420.CrossRefGoogle Scholar
  35. Stern, N. (2007). The economics of climate change: The Stern review. Cambridge: Cambridge University Press.Google Scholar
  36. Stern, N. (2008). The economics of climate change. The American Economic Review, 98(2), 1–37.CrossRefGoogle Scholar
  37. Tol, R. S. J. (2007). Europe’s long-term policy goal: A critical evaluation. Energy Policy, 35, 424–432.CrossRefGoogle Scholar
  38. UNDP. (2007). Human development report 2007/2008: Fighting climate change. New York: Palgrave Macmillan.Google Scholar
  39. UNEP. (2010). The emissions gap report: Are the Copenhagen accord pledges sufficient to limit global warming to 2 °C or 1.5 °C? Nairobi: UNEP.Google Scholar
  40. UNFCCC. (1992). United Nations framework convention on climate change. Bonn: UNFCCC.Google Scholar
  41. UNFCCC. (2009). Decision 2/CP.15. Copenhagen Accord, December 7–19 2009. Retrieved August 21, 2011, from
  42. UNFCCC. (2010, November 29–December 10). Outcome of the work of the ad hoc working group on long-term cooperative action under the convention. Draft decision -/CP.16. Cancun. Retrieved August 21, 2011, from
  43. Van der Sluijs, J., van Eijndhoven, J., Shackley, S., & Wynne, B. (1998). Anchoring devices in science for policy: The case of consensus around the climate sensitivity. Social Studies of Science, 28(2), 291–323.CrossRefGoogle Scholar
  44. WBGU. (1995). World in transition: Ways towards global environmental solutions. German Advisory Council on Global Change Flagship Report 1995. Berlin: Springer Verlag.Google Scholar
  45. WBGU. (1996). World in transition: The research challenge. German Advisory Council on Global Change Annual Report 1996. Berlin: Springer.Google Scholar
  46. WBGU. (1997). World in transition: Ways towards sustainable management of freshwater resources. German Advisory Council on Global Change Flagship Report. Berlin: Springer.Google Scholar
  47. WBGU. (2003). World in transition: New structures for global environmental policy. German Advisory Council on Global Change Flagship Report. London: Earthscan.Google Scholar
  48. WBGU. (2009). Climate change as a security risk. German Advisory Council on Global Change Flagship Report. London: Earthscan.Google Scholar
  49. Weitzman, M. L. (2009). On modelling and interpreting the economics of catastrophic climate change. The Review of Economics and Statistics, 91(1), 1–19.CrossRefGoogle Scholar
  50. Weitzman, M. L. (2010). GHG targets as insurance against catastrophic climate damages (Discussion Paper 10–42). The Harvard Project on International Climate Agreements. Cambridge: Harvard Kennedy School.Google Scholar
  51. WMO (World Meteorological Organization). (1988). Developing policies for responding to climatic change. A Summary of the Discussions and Recommendations of the Workshops held in Villach (28 September–2 October 1987) and Bellagio (9–13 November 1987) under the Auspices of the Beijer Institute, Stockholm, WMO/TD No. 225, Geneva.Google Scholar
  52. World Bank. (2010). World development report 2010 – Development and climate change. Washington, DC: World Bank.Google Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2012

Authors and Affiliations

  • Brigitte Knopf
    • 1
    Email author
  • Martin Kowarsch
    • 2
  • Christian Flachsland
    • 1
  • Ottmar Edenhofer
    • 1
  1. 1.Sustainable SolutionsPotsdam Institute for Climate Impact Research (PIK)PotsdamGermany
  2. 2.Institute for Social and Development Studies (IGP)Munich School of PhilosophyMunichGermany

Personalised recommendations