Computer models that project future climates are widely used for adaptation, mitigation and resilience planning. More than 50 such models were assessed and compared in the latest round of the Coupled Model Intercomparison Project, phase 6 (CMIP6), run by the World Climate Research Programme1. It is crucial that researchers know the best way to use those outputs to provide consistent information for climate science and policy. We are climate modellers and analysts who develop, distribute and use these projections. We know scientists must treat them with great care. Users beware: a subset of the newest generation of models are ‘too...