Scientists have calculated the years of life lost (YLL) attributed to exposure to “non-optimum” temperatures. It turns out that during the 2000s – supposedly the warmest years on record – people were still far more likely to die from exposure to cold temperatures than warm temperatures.
The country with the largest human population has recently experienced “the coldest records since the monitoring service first operated,” the “lowest [air temperature] in 44 years,” and “the coldest temperature in the past 59 years” during prolonged cold waves that directly led to excess mortality (Ho et al., 2020).
Early or excess deaths across China attributable to exposure to cold temperatures is far more common than early or excess deaths attributable to exposure to warm temperatures. This is not just true for China; it’s consistent with global trends.
“Gasparrini et al. (2015) studied 74,225,200 deaths in various periods across 384 worldwide locations between 1985 and 2012, and found that 7.29% of deaths were attributable to cold, while there were only 0.42% attributable to heat.”
Image Source: Ho et al., 2020
Three new studies calculate the attributable contribution of cold versus warm temperatures to early or excess deaths across China during the 2000s. Scientists found non-optimum temperatures led to 1.02 years of life lost (YLL) per two independent studies, whereas a third study suggests the non-optimum temperature YLL is 1.51 years.
All three studies reach the same conclusion: exposure to cold temperatures led to 0.89, 0.98, and 1.07 years of life lost out of 1.02, 1.02, and 1.51 years lost to non-optimum temperatures, respectively.
In other words, people were about 7 to 10 times more likely to die from exposure to cold temperatures during the supposedly warmest years on record.
“In general, 6.90% (95% confidence interval (CI): 4.62%, 9.18%) of YLLs [years of life lost] could be attributed to non-optimum temperatures at the national level, with differences across different regions, ranging from 5.36% (95% CI: −3.36%, 6.89%) in east region to 9.09% (95% CI: −5.55%, 23.73%) in northwest region. For each deceased person, we estimated that non-optimum temperature could cause a national-averaged 1.02 years (95% CI: 0.68, 1.36) of life loss, with a significantly higher effect due to cold exposure (0.89, 95% CI: 0.59, 1.19) than that of hot exposure (0.13, 95% CI: 0.09, 0.16).”