A presumed benefit of global warming is the assumption that warmer winter temperatures might decrease excessive winter deaths (EWDs) common in temperate climates. EWDs are defined as the difference between the number of deaths in a region during winter months (December – March) and the average of the proceeding fall and subsequent spring deaths. EWDs are attributable to a number of factors including higher incidences of cardio-respiratory and infectious diseases along with colder temperatures and icy conditions that can cause hypothermia and accidental falls.
With a predicted increase in winter temperatures due to global warming, it was previously assumed that EWDs might decrease. New research published in Nature Climate Change calls this assumption into question. The researchers used 60 years of data from England and Wales about EWDs and combined that with weather and other socioeconomic data. They then statistically analyzed the data to find factors that were associated with EWD trends and annual variation.
From 1951-1970, EWDs showed high yearly variation and a strong decreasing trend. From 1971-2000, the EWD variation halved and decreased more slowly. From 2001-2011 yearly variation became minimal and the EWD rate no longer decreased. The authors found that housing quality, heating costs, number of cold days and influenza activity were able to explain 77% of the EWD variation over the entire 60-year period. However, they found that after 1986 the number of cold days and cold days with large drops in temperature were no longer important predictors of EWDs. Furthermore, EWDs are now strongly correlated with flu activity. Through this analysis the authors have shown that better housing, standards of living and healthcare have all contributed to this decreasing trend. This analysis indicates that the predicted warmer winters will not offset other climate-related deaths.
On the contrary, the authors warn that the predicted increased variability in temperatures might lead to increased EWDs through severe cold spells since people will be less prepared for harsh weather. Furthermore, because of a generally growing and ageing population, total EWD numbers are likely to still increase.
Staddon, Philip L., Hugh E. Montgomery, and Michael H. Depledge. “Climate warming will not decrease winter mortality.” Nature Climate Change 4.3 (2014): 190-194.
Huang, Cunrui, and Adrian Barnett. “Human impacts: Winter weather and health.” Nature Climate Change 4.3 (2014): 173-174.