When an extreme weather event occurs, people often ask: is climate change to blame?
For decades, climate scientists have answered that question in general terms – that as the planet warms, we can expect many of these weather events to become more frequent and extreme.
But in recent years, advances in attribution science have allowed researchers to answer the question in much greater detail.
Founded in 2015 by Dr. Friederike Otto and Dr. Geert Jan van Oldenborgh, World Weather Attribution (WWA) scientists quantify how climate change influences the intensity and likelihood of an extreme weather event. They often do this using weather data and computer modelling, and often immediately in the aftermath of the extreme event.
To encourage actions that will make communities and countries more resilient to future extreme weather events, WWA studies also evaluate how existing vulnerability worsened the impacts of the extreme weather event.
The results are made public as soon as they are available, often days or weeks after the event, to inform discussions about climate change and extreme weather.
For example, in July 2021, just 11 days after temperatures in Pacific northwest areas of the U.S. and Canada reached high above 40ºC, shattering records by as much as 5ºC, a WWA study found that climate change made the heatwave at least 150 times more likely and 2ºC more intense.
The WWA initiative was formed in 2015 and has now performed more than 50 attribution studies on heatwaves, extreme rainfall, drought, floods and forest fires around the world. The methods used have been improved over the years and have been published in the peer-reviewed scientific literature together with many of the studies of individual events.
To contact World Weather Attribution, email wwamedia@imperial.ac.uk