Impact of sudden stratospheric warmings on United Kingdom mortality

Sudden stratospheric warmings (SSWs) during boreal winter are one of the main drivers of sub-seasonal climate variability in the Northern Hemisphere. Although the impact of SSW events on surface climate and climate extremes has been clearly demonstrated, the impact of the resulting climate anomalies on society has not been so widely considered. In the United Kingdom (UK), SSWs are associated with cold weather, which is linked to significant increases in mortality. This study demonstrates, for the first time, that SSWs are linked to increases in mortality in the UK. A distributed lag nonlinear model and standard parameter settings from the literature is used to construct a daily time series of UK deaths attributable to cold weather between 1991 and 2018. Weekly mortality associated with SSWs is diagnosed using a superposed epoch analysis of attributed mortality for the 15 SSW events in this period. SSW associated mortality peaks between 3 and 5 weeks after SSW central date and leads to, on average, 620 additional deaths in the same period. Given that the impacts of SSWs can be skilfully predicted on sub-seasonal timescales, this suggests that health and social care systems could derive substantial benefit from sub-seasonal forecasts during SSWs.

Automated summary

This study demonstrates the link between sudden stratospheric warmings (SSWs) and increased mortality in the UK, particularly following cold weather events. SSW associated mortality peaks between 3 and 5 weeks after the central date, leading to an average of 620 additional deaths during this period. Sub-seasonal forecasts during SSWs could potentially benefit health and social care systems.