Challenges and Stakes of Attributing Extreme Weather Events

On a sunny Friday afternoon in late November, less than a dozen people stared at the screen in an unadorned classroom at the Florence Botanical Garden. Instead of walking down the pathways and popping into the lush greenhouses, they listened to climate scientist Erika Coppola speak via Meet from her office at the International Center of Theoretical Physics (ICTP) Abdus Salam in Trieste, Italy. The talk’s title was “The Changing Climate, the Mediterranean We Might Expect.” Magma was the main organizer.

About 20 days earlier, a flooding event had hit the plain between Florence, Prato and Pistoia, which is only eight miles from where the talk was held. Wondering about the role of climate change in the aftermath of the flood was inevitable.

“Whenever such an event occurs,” Coppola said, “‘What is the role of climate change?’ is the question we get the most.”

To accurately answer this type of question, a new research area focusing on extreme event attribution has emerged, especially in the past ten years. One of the initiatives in this field that we most frequently mention in our newsletters, World Weather Attribution, for instance, was formed by climatologist and physicist Geert Jan van Oldenborgh and Imperial College London senior lecturer Friederike Otto in 2015. In her talk, Coppola introduced us to another one: ClimaMeter, a web tool interface coordinated by the French research organization Pierre-Simon Laplace Institute (IPSL) and developed with colleagues based in Italy and other parts of the world in the second half of 2023.