Attribution of multi-annual to decadal changes in the climate system: The Large Ensemble Single Forcing Model Intercomparison Project (LESFMIP)

Multi-annual to decadal changes in climate are accompanied by changes in extreme events that cause major impacts on society and severe challenges for adaptation. Early warnings of such changes are now potentially possible through operational decadal predictions. However, improved understanding of the causes of regional changes in climate on these timescales is needed both to attribute recent events and to gain further confidence in forecasts. Here we document the Large Ensemble Single Forcing Model Intercomparison Project that will address this need through coordinated model experiments enabling the impacts of different external drivers to be isolated. We highlight the need to account for model errors and propose an attribution approach that exploits differences between models to diagnose the real-world situation and overcomes potential errors in atmospheric circulation changes. The experiments and analysis proposed here will provide substantial improvements to our ability to understand near-term changes in climate and will support the World Climate Research Program Lighthouse Activity on Explaining and Predicting Earth System Change.

Automated summary

Multi-annual to decadal changes in climate are accompanied by changes in extreme events, which have major impacts on society and pose severe challenges for adaptation. Operational decadal predictions offer the potential for early warnings of these changes. However, understanding the causes of regional climate changes on these timescales is crucial for attributing recent events and increasing confidence in forecasts. The Large Ensemble Single Forcing Model Intercomparison Project aims to address this need through coordinated model experiments and an attribution approach that accounts for model errors.