 When it comes to interpreting ensemble projections, a range of views and methodologies have emerged. At one end of the spectrum, there are statistical methodologies used to infer probabilities (of future changes in climate) from ensemble results. For instance, some MME studies have adopted what amounts to a “truth-plus-error” framework: probabilities are estimated by treating ensemble members as random draws from a distribution of possible models centered on truth (e.g., Tebaldi et al. 2005). The performance of today’s MMEs on past data, however, suggests that they are not centered on truth (Knutti et al. 2010a). An alternative “statistically-indistinguishable” framework allows for the estimation of probabilities by assuming that ensemble members and truth (i.e., perfect observations of future conditions) are drawn from the same statistical distribution. Examining past data, Annan and Hargreaves (2010) find this assumption to roughly hold for one prominent MME (the CMIP3 ensemble), at least for some variables. Bishop and Abramowitz (2013), however, argue that results from today’s MMEs lack some statistical properties that should be present if the assumption of indistinguishability is accurate. They propose an alternative “replicate-Earth” framework, which involves post-processing MME projections so that they display those desired statistical properties; Bishop and Abramowitz do not seem to insist, however, that the post-processed distribution be considered a probability distribution. Bayesian methodologies have also been developed. The UKCP09 project, for example, used a Bayesian PPE methodology to produce probabilistic climate change projections out to 2100 at a fine spatiotemporal resolution for the United Kingdom (Murphy et al. 2009). That methodology treated parameter uncertainty as uncertainty about which model was the best (on given metrics of performance) in a given model class, and attempted to account for the difference between the best model and a perfect model with the help of results from an MME (Rougier 2007; Sexton et al. 2012). 