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Climate sensitivity uncertainty: when is good news bad?

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journal contribution
posted on 11.09.2015 by Mark Freeman, G. Wagner, R.J. Zeckhauser
Climate change is real and dangerous. Exactly how bad it will get, however, is uncertain. Uncertainty is particularly relevant for estimates of one of the key parameters: equilibrium climate sensitivity—how eventual temperatures will react as atmospheric carbon dioxide concentrations double. Despite significant advances in climate science and increased confidence in the accuracy of the range itself, the “likely” range has been 1.5-4.5°C for over three decades. In 2007, the Intergovernmental Panel on Climate Change (IPCC) narrowed it to 2-4.5°C, only to reverse its decision in 2013, reinstating the prior range. In addition, the 2013 IPCC report removed prior mention of 3°C as the “best estimate.” We interpret the implications of the 2013 IPCC decision to lower the bottom of the range and excise a best estimate. Intuitively, it might seem that a lower bottom would be good news. Here we ask: When might apparently good news about climate sensitivity in fact be bad news in the sense that it lowers societal wellbeing? The lowered bottom value also implies higher uncertainty about the temperature increase, a definite bad. Under reasonable assumptions, both the lowering of the lower bound and the removal of the “best estimate” may well be bad news.

History

School

  • Business and Economics

Department

  • Business

Published in

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences

Citation

FREEMAN, M.C., WAGNER, G. and ZECKHAUSER, R.J., 2015. Climate sensitivity uncertainty: when is good news bad?. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 373: 20150092.

Publisher

© The Royal Society

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2015

Notes

This paper was accepted for publication in the journal Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences and the definitive published version is available at http://dx.doi.org/10.1098/rsta.2015.0092

ISSN

1471-2962

Language

en

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