General circulation models(GCMs)have progressed enor-mously over the last few decades and they have allowed huge advances in forecasting at every timescale,from daily to seasonal and decadal,and in climate simulations of the Earth climate sys-tem.These advances have increased the relevance of the results for decision-making and the drafting of strategies and policies with far-reaching impacts.In fact,they provide the foundation of the global conversation on climate change mitigation and adap-tation.Even the complex international negotiation,taking place in the context of the Paris Agreement and the UN Framework Convention on Climate Change,is ultimately based on science obtained mostly with global and regional models.