Explaining extreme weather

Attributing extreme weather events to specific (combinations of) causes is a complex science. A new report presents 19 analyses, by 18 research groups, of 12 extreme events from 2012. The report also provides an opportunity to observe the uncertainty inherent in attribution due to differences in methodological approaches (the research groups involved used a variety of approaches), and a chance to compare and contrast the strengths and weaknesses of these methods (as some events were analysed, differently, by multiple research groups). About half of the anaylses found that anthropogenic climate change contributed to the event studied, though of course other factors (such as natural weather variations) also shaped how the events unfolded.

Those compiling the report note that predicting and attributing extreme events are linked, but in complex ways: predicting events based on contributing factors to previous ones involves understanding the extent to which each factor was important, as well as how the interplay between factors changed the event. This kind of prediction and attribution is one of six ‘grand challenges’ identified by the World Climate Research Programme, challenges that: face specific barriers, could see significant progress over the next 510 years with targeted efforts, are measurable, can transform, are capable of capturing public imagination, and offer compelling storylines.