News release: “Can good news actually be bad news when it comes to the effects of global climate change?  That is the question Harvard Kennedy School (HKS) Professor Richard Zeckhauser and his co-authors are attempting to answer in a new HKS Faculty Research Working Paper.  Their report, titled Climate Sensitivity Uncertainty: When is Good News Bad? sheds new light on the critical intersection of climate science, risk and rewards, and society’s optimal “willingness to pay” (WTP) to address the problem.  Starting with the premise that science knows unchecked climate change is bad without knowing precisely how bad, the researchers examined the impact of the 2013 decision by the Intergovernmental Panel on Climate Change (IPCC) to reverse a prior decision to increase by one half of a degree Celsius the lower range of what it deems to be the “likely” range and to remove mention altogether of its “best estimate” of what happens to future global temperatures as carbon concentrations in the atmosphere double. “That step points to deep-seated uncertainties inherent in climate science and, thus, policy: thirty-five years of amazing advances in most every aspect of climate science apparently have not tightened the range for the eventual realization of this fundamental parameter. Indeed, they have taught us to be more cautious in defining it,” the authors write. Zeckhauser and his co-authors Mark C. Freeman and Gernot Wagner found that what on the surface appears to be good news from the IPCC could indeed portend even greater costs of unmitigated global warming.”