Metrics to quantify performance, energy and CO₂ footprint of CMIP7 simulations

Climate simulations are becoming increasingly complex, with each CMIP phase introducing more sophisticated models, a greater number of experiments, and larger ensembles, leading to a continuous rise in computational requirements. These simulations rely on some of the world’s most powerful supercomputers, which consume energy to reproduce the Earth’s climate. Yet, efforts to systematically quantify the computational cost, energy use, and environmental impact of CMIP activities have so far been limited. The Energy Consumption and Carbon Footprint Task Team was established to address this gap by measuring and reporting these aspects for the upcoming CMIP phase, CMIP7. For CMIP7, participating modelling centres are asked to report energy consumption, which enables the estimation of the carbon footprint associated with running climate model experiments. Modelling centres participating in CMIP7 are asked to provide these metrics for the experiments they are running for CMIP7 Assessment Fast Track and community MIPs. Version 1.2 updates the guidelines for Data Output Cost metric and fixes broken links. Version 1.3 updates the guidelines to remove reference to 'mandatory collection' of metrics and changes this to 'strongly recommended'. Also added further clarification of the dissemination process and the benefits for modelling centres to take part. Version 1.4 updates the Annex describing 'Computing the Number of grid points'.