ECI’s unique approach uses very large ensembles of simulations of regional climate models to run two different analyses: to represent the current climate as it was observed, and to represent the same events in the world that might have been without human-induced climate change.
This methodological approach is supported by its widespread use in submissions to the annual Bulletin of the American Meteorological Society Special Issue on Explaining Extreme Events from a Climate Perspective. This analysis used very large ensembles of a regional climate model over Europe embedded in a global circulation model to assess the change in risk of extreme precipitation under two very distinct versions of the event:
- the observed extreme weather event itself, and
- a model of the extreme weather event with the impact of anthropogenic greenhouse gas emissions removed.
Using a distributed computing framework — weather@home — members of the public facilitate multi-thousand-member ensemble weather simulation experiments at both global and regional scales.
To accelerate the attribution analysis, the ECI team has developed a novel approach based on using forecast sea surface temperatures (SSTs) instead of observed SSTs. The team used the 2014 United Kingdom floods as a case study to demonstrate the robustness of this approach.