Climatic Change

, Volume 124, Issue 1–2, pp 21–37

Scientific uncertainty and climate change: Part I. Uncertainty and unabated emissions

  • Stephan Lewandowsky
  • James S. Risbey
  • Michael Smithson
  • Ben R. Newell
  • John Hunter

DOI: 10.1007/s10584-014-1082-7

Cite this article as:
Lewandowsky, S., Risbey, J.S., Smithson, M. et al. Climatic Change (2014) 124: 21. doi:10.1007/s10584-014-1082-7


Uncertainty forms an integral part of climate science, and it is often used to argue against mitigative action. This article presents an analysis of uncertainty in climate sensitivity that is robust to a range of assumptions. We show that increasing uncertainty is necessarily associated with greater expected damages from warming, provided the function relating warming to damages is convex. This constraint is unaffected by subjective or cultural risk-perception factors, it is unlikely to be overcome by the discount rate, and it is independent of the presumed magnitude of climate sensitivity. The analysis also extends to “second-order” uncertainty; that is, situations in which experts disagree. Greater disagreement among experts increases the likelihood that the risk of exceeding a global temperature threshold is greater. Likewise, increasing uncertainty requires increasingly greater protective measures against sea level rise. This constraint derives directly from the statistical properties of extreme values. We conclude that any appeal to uncertainty compels a stronger, rather than weaker, concern about unabated warming than in the absence of uncertainty.


Uncertainty unabated emissions decision making 

Supplementary material

10584_2014_1082_MOESM1_ESM.pdf (252 kb)
(PDF 251 KB)

Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  • Stephan Lewandowsky
    • 1
    • 2
  • James S. Risbey
    • 3
  • Michael Smithson
    • 4
  • Ben R. Newell
    • 5
  • John Hunter
    • 6
  1. 1.University of Western AustraliaPerthAustralia
  2. 2.University of BristolBristolUK
  3. 3.CSIRO Marine and Atmospheric ResearchHobartAustralia
  4. 4.Australian National UniversityCanberraAustralia
  5. 5.University of New South WalesSydneyAustralia
  6. 6.Antarctic Climate & Ecosystems Cooperative Research CentreHobartAustralia

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