Has the risk of a 1976 north‐west European summer drought and heatwave event increased since the 1970s because of climate change?. (13th October 2021)

• Record Type: Journal Article
• Authors: Baker, Laura; Shaffrey, Len; Hawkins, Ed
• Is Part Of: Quarterly journal of the Royal Meteorological Society. Volume 147:Number 741(2021)
• Page Start: 4143
• Page End: 4162
• Publication Date: 2021-10-13
• Subjects: attribution -- climate change -- drought -- extreme -- heatwave -- risk; Meteorology -- Periodicals; 551.5
• DOI: 10.1002/qj.4172
• Languages: English
• ISSNs: 0035-9009

Abstract

Abstract: In the summer of 1976, north‐west Europe experienced an exceptional heatwave and drought, which impacted agriculture and public water supply. This study aims to assess how the likelihood of the event in the present‐day climate has changed since 1976 because of climate change. The analysis focuses on the England and Wales region, which was particularly badly impacted. Three key factors contributing to the extreme summer were identified: the dry preceding winter–spring period, the dry summer and the hot summer. Following the principles of event attribution, three methods are used to evaluate the change in event risk: one using observational data, a second using CMIP5 coupled climate models and a third using HadGEM3‐A atmosphere‐only simulations. This is the first time that this method has been used to evaluate how the risk of a historical extreme event has changed since it originally occurred. The results from the three methods agree qualitatively. The probability of a summer at least as hot as 1976 has increased significantly between the 1970s and the present‐day climate (estimated risk ratios 11 (5–95% confidence interval (CI) [7, 14]), 9 (CI [4, 28]) and 19 (CI [5, 25]) based on the three respective methods). In contrast, no significant change in the probability of an extreme dry winter–spring or an extreme dry summer was found. However, the joint probability of an extreme dry winter–spring followed by an extreme hot summer and the probability of an extreme hot and dry summer have both increased significantly between the 1970s and the present day (estimated risk ratios between 5 and 79, and between 3 and 39, respectively). Water resource systems should therefore be robust enough to cope with more frequent occurrences of summers as extreme as 1976. Abstract : The risk of the 1976 summer drought in the England and Wales region is assessed in the 1970s and present‐day climate. The risk of an extreme hot summer is found to have increased significantly while the risk of an extreme dry winter‐spring or summer have not. However, the combined risk of a hot and dry summer or dry winter‐spring have increased significantly.