Paper Reviewed
Vuteovici, M., Goldberg, M.S. and Valois, M.-F. 2014. Effects of diurnal variations in temperature on non-accidental mortality among the elderly population of Montreal, Quebec, 1984-2007. International Journal of Biometeorology 58: 843-852.

In a study published in the International Journal of Biometeorology, Vuteovici et al. (2014) report that (1) "in Shanghai, a time-series analysis showed a 1.37% increase in total non-accidental mortality, a 1.86% increase in cardiovascular mortality, and a 1.29% increase in respiratory mortality for a 1°C increase in the 3-day moving average for diurnal temperature range (Kan et al., 2007)," that (2) "subsequent studies showed a 1.25% increase in deaths from chronic obstructive pulmonary disease for a 1°C increase in the 4-day moving average of diurnal temperature range (Song et al., 2008) and a 2.46% increase in coronary heart disease mortality for a 1°C increase in the 2-day lagged diurnal temperature range (Cao et al., 2009)," and that (3) the latter group of researchers had additionally reported "a 2.13% increase per 1°C increase in the 2-day lagged diurnal temperature range."

Similarly, Vuteovici et al. write that (4) "in Hong Kong, Tam et al. (2009) reported a 1.7% increase in cardiovascular mortality among the elderly per 1°C increase in diurnal temperature range at lag days 0-3, while (5) in Shanghai, Liang et al. (2009) found a 14% increase in the number of hospital admissions for chronic obstructive pulmonary disease with each 1°C increase in the diurnal temperature range above 9.6°C." And in their own study of the impact of variations of diurnal temperature on daily mortality of residents of Montreal aged 65 years and older during the period 1984-2007, they say they found "a 5.12% increase in the cumulative effects on mortality for an increase of the diurnal temperature range from 6°C to 11°C," and that when the diurnal temperature range increased from 11°C to 17.5°C, they found an 11.27% increase in mortality.

The reason these findings are so important within the context of global warming is that Karl et al. (1984, 1991) had found several years earlier that over the course of 20th-century global warming, daily minimum temperatures typically rose at a rate that was fully three times greater than the rate of daily maximum temperature rise over most of the world, which resulted in a significant reduction in diurnal temperature range throughout the better part of the inhabited portions of the planet over that time period, which should thus have significantly reduced the percentage of the human population dying each year from the various health challenges listed above.

References
Cao, J., Cheng, Y., Zhao N., Song, W., Jiang, C., Chen, R. and Kan, H. 2009. Diurnal temperature range is a risk factor for coronary heart disease death. Journal of Epidemiology 19: 328-332.

Kan, H., London, S.J., Chen, H., Song, G., Chen, G., Jiang, L., Zhao, N., Zhang, Y. and Chen, B. 2007. Diurnal temperature range and daily mortality in Shanghai, China. Environmental Research 103: 424-431.

Karl, T.R., Jones, P.D., Knight, R.W., Kukla, G., Plummer, N., Razuvayev, V., Gallo, K.P., Lindseay, J., Charlson, R.J. and Peterson, T.C. 1984. A new perspective on recent global warming: asymmetric trends of daily maximum and minimum temperature. Bulletin of the American Meteorological Society 74: 1007-1023.

Karl, T.R., Kukla, G., Razuvayev, V.N., Changery, M.J., Quayle, R.G., Heim Jr., R.R., Easterling, D.R. and Fu, C.B. 1991. Global warming: evidence for asymmetric diurnal temperature change. Geophysical Research Letters 18: 2253-2256.

Liang, W.M., Liu, W.P. and Kuo, H.W. 2009. Diurnal temperature range and emergency room admissions for chronic obstructive pulmonary disease in Taiwan. International Journal of Biometeorology 53: 17-23.

Song, G., Chen, G., Jiang, L., Zhang, Y., Zhao, N., Chen, B. and Kan, H. 2008. Diurnal temperature range as a novel risk factor for COPD death. Respirology 13: 1066-1069.

Tan, W.W.S., Wong, T.W., Chair, S.Y. and Wong, A.H.S. 2009. Diurnal temperature range and daily cardiovascular mortalities among the elderly in Hong Kong. Archives of Environmental and Occupational Health 64: 202-206.