Yang, Z., Wang, Q. and Liu, P. 2019. Extreme temperature and mortality: evidence from China. International Journal of Biometeorology 63: 29-50.
Writing as background for their work, Yang et al. (2019) note that the majority of studies to date examining the relationship between temperature and mortality focus only on the hot end (heat wave) of the temperature spectrum. Consequently, much less is known about temperature-induced mortality at the cold end of the temperature spectrum due to cold weather.
As their contribution to this subject, the three Chinese scientists conducted a nationwide analysis of the impact of temperature on all-cause mortality using data from 70 cities across China over the period 2002-2013. In all, twelve temperature-related indices were analyzed in relation to the mortality data, six of which pertained to hot weather extremes and six of which pertained to cold weather extremes.
In discussing their findings, Yang et al. report that changes in extreme hot and cold temperature indicators were generally both positively and significantly associated with mortality. However, the effects of cold weather events were consistently more deadly than warm weather events. For example, annual death rates attributed to cold spell durations were 42.5% greater than those due to warm spell durations.
The authors also found evidence of regional acclimation, where death rates due to extreme hot weather were larger in northern China than in southern China. Similarly, cold-induced temperature mortality rates in the south tended to be greater than rates in the north. Nevertheless, the annual deaths due to cold weather events across China are presently a serious health threat, where death rates “exceed the mortality from leukemia and brain tumors.”
Lastly, Yang et al. also stratified their findings by economic progress (represented by GDP). Doing so revealed that “low-GDP cities were the most affected regions by the extreme temperature events in China,” where “the health of people living in low-GDP areas was especially susceptible to the effects of extreme cold spell duration.”
In considering the above findings, clearly, cold weather events represent a much greater threat to human health than warm weather events, and those threats are magnified in poorer regions where citizens do not have as many resources or technological capabilities to adequately prepare for and endure such potentially deadly weather events. Given as much, it is ironic that many policy makers support restrictions on fossil fuel use because of their concerns about potential harms from global warming, especially since (1) a little global warming would likely produce a net saving of lives (a greater reduction in cold-related deaths than increase in warm-related ones), and (2) fossil fuel use is intrinsically coupled with GDP, so any reduction in fossil fuels use would likely lead to a reduction in GDP and, hence, increase temperature-related mortality.
This article appeared on the CO2 Science website at http://www.co2science.org/articles/V22/jun/a6.php