What are the relative roles of large-scale, regional and local scale processes, as well as their interactions, for the formation of extremes?
Are models able to reliably simulate extremes and their changes, and how can this be evaluated and improved?
What are the contributors to observed extreme events and to changes in the frequency and intensity of the observed extremes?
Weather and climate extremes are an inherent part of climate. There is overwhelming evidence that the climate and its extremes are changing. As extremes affect every aspect of our society, decision- and policy makers, and stakeholders are increasingly asking for reliable predictions of extremes on time scales from days to seasons and centuries. To meet this societal need, the world climate research community is challenged by underlying science questions and the quality and coverage of the observational data that are used to monitor and understand extremes.
Both the questions and the data need urgent attention in order to better identify the factors and mechanisms that determine the location, intensity, and frequency of various climate extremes including droughts, floods, heavy precipitation events, heat waves, cold spells, tropical and extratropical storms, coastal sea level surges and ocean waves. This information is needed in the near-term (from a season to a year) to mitigate risks to society and ecosystems, and in the longer term (from a decade to centuries) for effective adaptation planning. Despite the importance of the topic, progress has been fairly slow. However, recent developments suggest that the prospects for more rapid advancement of this WCRP Grand Challenge are excellent. For more infomation read the white paper.
The Extremes Grand Challenge is organised around four over arching themes (Document, Understand, Simulate, Attribute) with a main focus on four core events (Heavy Precipitation, Heatwave, Drought, Storm).
Now published: WCRP Special Issue of Weather and Climate Extremes Journal, Vol. 9 (Grand Challenge on Extremes - WCRP-ICTP Summer School on Attribution and Prediction of Extreme Events)
Note: In April 2017 the leadership of the 'Grand Challenge on Understanding and Predicting Weather and Climate Extremes' changed its name to the 'Grand Challenge on Weather and Climate Extremes'.