Extreme heat events are associated with spikes in mortality, yet death rates are on average highest during the coldest months of the year. Under the assumption that most winter excess mortality is due to cold temperature, many previous studies have concluded that winter mortality will substantially decline in a warming climate. We analyzed whether and to what extent cold temperatures are associated with excess winter mortality across multiple cities and over multiple years within individual cities, using daily temperature and mortality data from 36 US cities (1985-2006) and 3 French cities (1971-2007). Comparing across cities, we found that excess winter mortality did not depend on seasonal temperature range, and was no lower in warmer vs. colder cities, suggesting that temperature is not a key driver of winter excess mortality. Using regression models within monthly strata, we found that variability in daily mortality within cities was not strongly influenced by winter temperature. Finally we found that inadequate control for seasonality in analyses of the effects of cold temperatures led to spuriously large assumed cold effects, and erroneous attribution of winter mortality to cold temperatures. Our findings suggest that reductions in cold-related mortality under warming climate may be much smaller than some have assumed. This should be of interest to researchers and policy makers concerned with projecting future health effects of climate change and developing relevant adaptation strategies.

中文翻译：

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冬季死亡率：气候变暖会带来好处吗？

极端高温事件与死亡率飙升有关，但平均死亡率在一年中最冷的月份最高。假设大多数冬季过量死亡率是由寒冷造成的，之前的许多研究得出的结论是，在气候变暖的情况下，冬季死亡率将大幅下降。我们利用美国 36 个城市（1985-2006 年）和法国 3 个城市（1971-2007 年）的每日气温和死亡率数据，分析了寒冷气温是否与多个城市以及单个城市内多年的冬季死亡率过高相关。 。比较各个城市，我们发现冬季超额死亡率并不取决于季节温度范围，而且温暖城市与寒冷城市的死亡率并不低，这表明温度并不是冬季超额死亡率的关键驱动因素。使用月度分层内的回归模型，我们发现城市内每日死亡率的变化并没有受到冬季温度的强烈影响。最后，我们发现，在分析低温影响时对季节性控制不充分，导致了虚假的大假设寒冷影响，并将冬季死亡率错误地归因于低温。我们的研究结果表明，在气候变暖的情况下，与寒冷相关的死亡率的下降可能比一些人想象的要小得多。关注预测气候变化未来健康影响并制定相关适应策略的研究人员和政策制定者应该对此感兴趣。