Gernot Wagner

Harvard Paulson School
26 Oxford Street 424B
Cambridge, MA 02138

E-Mail: EmailAddress: hidden: you can email any NBER-related person as first underscore last at nber dot org

NBER Working Papers and Publications

November 2016Applying Asset Pricing Theory to Calibrate the Price of Climate Risk
with Kent D. Daniel, Robert B. Litterman: w22795
Pricing greenhouse gas emissions involves making trade-offs between consumption today and unknown damages in the (distant) future. This setup calls for an optimal control model to determine the carbon dioxide (CO2) price. It also relies on society’s willingness to substitute consumption across time and across uncertain states of nature, the forte of Epstein-Zin preference specifications. We develop the EZ-Climate model, a simple discrete-time optimization model in which uncertainty about the effect of CO2 emissions on global temperature and on eventual damages is gradually resolved over time. We embed a number of features including potential tail risk, exogenous and endogenous technological change, and backstop technologies. The EZ-Climate model suggests a high optimal carbon price today t...
January 2015Climate Sensitivity Uncertainty: When is Good News Bad?
with Mark C. Freeman, Richard J. Zeckhauser: w20900
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...

Published: Mark C. Freeman & Gernot Wagner & Richard J. Zeckhauser, 2015. "Climate sensitivity uncertainty: when is good news bad?," Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol 373(2055).

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