World Weather Attribution

World Weather Attribution (WWA) is an international effort to analyse and communicate the possible influence of climate change on extreme weather events, such as storms, extreme rainfall, heatwaves, cold spells, and droughts.

Recognising society’s interest in reducing the human, economic, and environmental costs of weather-related disasters, WWA delivers timely and scientifically reliable information on how extreme weather may be affected by climate change.

Recent studies have quantified the impact of climate change on the likelihood and intensity of bushfires, heatwaves and storms.

Through extensive media engagement – including the Guardian, the Daily Mail, the Times, Scientific American, CBS, BBC and many more – WWA has helped to change the global conversation around climate change, influencing adaptation strategies and paving the way for new sustainability litigation. In 2020, climate change attribution was named one of MIT Tech Review’s top ten breakthrough technologies.

WWA is a partnership of:

  • Environmental Change Institute, University of Oxford (ECI)
  • Royal Netherlands Meteorological Institute (KNMI)
  • Laboratoire des Sciences du Climat et de l’Environment (LSCE)
  • University of Princeton
  • National Center for Atmospheric Research (NCAR)
  • Red Cross Red Crescent Climate Centre (The Climate Centre).

WWA was initiated in late 2014 after the scientific community concluded that the emerging science of extreme event attribution could be operationalised. It is hosted at the Environmental Change Institute, University of Oxford, and co-led by Dr Geert Jan van Oldenborgh (KNMI) and Dr Friederike Otto (ECI).

Science partners at WWA utilise established peer-reviewed methods to perform their attribution assessments. We regularly include additional international scientists to develop greater regional capacity and geographic reach.

Identifying a human fingerprint on individual extreme weather events —“probabilistic extreme event attribution” — has been an important goal of the scientific community for more than a decade. In 2004, Stott et al., published a paper in Nature showing that climate change had at least doubled the risk of the record-breaking 2003 European summer heatwave that resulted in the deaths of tens of thousands of people.

Since then, advances in the field have prompted numerous studies, leading the Bulletin of the American Meteorological Society (BAMS) to dedicate an annual special issue to extreme event attribution for the past four years. In a report issued in 2016 the National Academies of Sciences, Engineering and Medicine, titled:

WWA applies a unique scientific approach that combines observational data, analysis of a range of models, peer reviewed research, and on-the-ground reports. This innovative combination, built on existing, peer-reviewed methods, enables us to conduct more rapid analyses and provide faster answers to pressing questions about high-impact events – how strong the likelihood is, for example, of similar weather-related disasters in the future.

WWA considers all types of extreme weather events, including extreme heat and cold, heavy rainfall and floods, droughts, heavy snowfall, and storm surges. In cases where the probability of the event appears to have been changed due to climate change, we quantify the size of that change in order to assess the scale of the contribution from global warming. The types of events for which a quantitative analysis can be performed will expand as new attribution techniques become available and the science matures.

“The goal of this ambitious effort is to use peer reviewed science to provide decision makers, the public, and the media with early, science-based answers to the questions of whether and to what extent global warming caused by greenhouse gas emissions played a role in an event’s probability and magnitude,” said Dr. Friederike Otto, of the ECI.

“Our team believes that a careful science-based assessment is extremely valuable, even in cases where we can’t provide hard numbers,” said Dr. Maarten van Aalst, Director of the Red Cross Red Crescent Climate Centre. “It is important to recognize that ‘we don’t know’ or ‘there is no significant trend’ are also valid findings.” This work also helps to answer questions about trends in risk and vulnerability, and the role of human activity in extreme weather.

WWA’s mission is supported by the 2016 BAMS special issue, which concluded, “Progress in managing risks from extreme events can only be made if the foundational pillars of observations, modeling, and our understanding of the physical processes that drive extreme events and their relationship to climate change also continue to improve. Continued investments in climate science at all levels are crucial not only in the next five years, but for the foreseeable future.”

By providing a clear scientific statement, WWA injects more rigorous analysis and science-based information into coverage of — and public knowledge and discourse on — extreme weather and its relationship with climate change.