A Representative Democracy to reduce interdependency in a 1 multi - model ensemble

6 The collection of Earth System Models available in the CMIP5 archive represents, at least to 7 some degree, a sample of uncertainty of future climate evolution. The presence of duplicated 8 code as well as shared forcing and validation data in the multiple models in the archive 9 raises at least three potential problems; biases in the mean and variance, the overestimation 10 of sample size and the potential for spurious correlations to emerge in the archive due to 11 model replication. Analytical evidence is presented to demonstrate that the distribution 12 of models in the CMIP5 archive is not consistent with a random sample, and a weighting 13 scheme is proposed to reduce some aspects of model co-dependency in the ensemble. A 14 method is proposed for selecting diverse and skillful subsets of models in the archive which 15 could be used for impact studies in cases where physically consistent joint projections of 16 multiple variables (and their temporal and spatial characteristics) are required. 17