- Joint Program Report
Report
Abstract/Summary:
Communicating uncertainty in climate projections provides essential information to decision makers, allowing them to evaluate how policies might reduce the risk of climate impacts. In ongoing work, we use quantitative uncertainty techniques to develop this information. As an illustration of the approach we find that, absent mitigation policies, our median projection shows a global mean surface temperature rise from 1990 to 2100 of 2.3 degrees C, with a 95% confidence interval of 0.9 degrees C to 5.3 degrees C. The Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC) reports a range for the global mean surface temperature rise by 2100 of 1.4 to 5.8 degrees C but does not provide likelihood estimates for this key finding although it does for others.