When don’t we need a new extreme event attribution study?

The influence of anthropogenic climate change on the frequency and intensity of extreme weather events is becoming increasingly well understood. Extreme event attribution studies now exist for hundreds of events over the past few decades. However, there remain large heterogeneities in the number of attribution studies across the world and for different hazards, as well as limited capacity to conduct new studies. In this study, we suggest that there is more information to draw from past attribution studies about recent events. This is because, even though anthropogenic forcing continues to increase, many new events share meteorological characteristics with previously attributed ones. Here, we explore the possibility of using related studies and other lines of existing evidence such as projections and trend analysis to create rapid, low-resource attribution statements. To do this, we discuss the potential use cases for attribution results, including raising awareness of climate risks, preparing adaptation measures and attributing climate loss and damage. Then we discuss the considerations necessary to fulfil these uses in three cases studies, including a heatwave in the UK, a tropical storm in the Caribbean and a drought in East Africa. To conclude, we highlight the regions and hazards for which information can be drawn without new quantitative analysis, and those in which it remains urgent. This could aid prioritisation of limited resources for research into less well understood regions and hazards.