Abt Associates, Boulder, CO, USA.
US Environmental Protection Agency, Washington, DC, USA.
Lancet Planet Health. 2021 Jun;5(6):e338-e346. doi: 10.1016/S2542-5196(21)00058-9. Epub 2021 May 20.
Extreme heat exposure can lead to premature death. Climate change is expected to increase the frequency, intensity, and duration of extreme heat events, resulting in many additional heat-related deaths globally, as well as changing the nature of extreme cold events. At the same time, vulnerability to extreme heat has decreased over time, probably due to a combination of physiological, behavioural, infrastructural, and technological adaptations. We aimed to account for these changes in vulnerability and avoid overstated projections for temperature-related mortality. We used the historical observed decrease in vulnerability to improve future mortality estimates.
We used historical mortality and temperature data from 208 US cities to quantify how observed changes in vulnerability from 1973 to 2013 affected projections of temperature-related mortality under various climate scenarios. We used geographically structured meta-regression to characterise the relationship between temperature and mortality for these urban populations over the specified time period. We then used the fitted relationships to project mortality under future climate conditions.
Between Oct 26, 2018, and March 9, 2020, we established that differences in vulnerability to temperature were geographically structured. Vulnerability decreased over time in most areas. US mortalities projected from a 2°C increase in mean temperature decreased by more than 97% when using 2003-13 data compared with 1973-82 data. However, these benefits declined with increasing temperatures, with a 6°C increase showing only an 84% decline in projected mortality based on 2003-13 data.
Even after accounting for adaptation, the projected effects of climate change on premature mortality constitute a substantial public health risk. Our work suggests large increases in temperature will require additional mitigation to avoid excess mortality from heat events, even in areas with high air conditioning coverage in place.
The US Environmental Protection Agency and Abt Associates.
暴露在极端高温下会导致过早死亡。预计气候变化将增加极端高温事件的频率、强度和持续时间，从而在全球范围内导致更多与高温有关的死亡，同时改变极端寒冷事件的性质。与此同时，随着时间的推移，人们对极端高温的脆弱性有所降低，这可能是由于生理、行为、基础设施和技术适应的综合作用。我们旨在考虑到这种脆弱性的变化，避免对与温度相关的死亡率做出过高的预测。我们利用历史上观察到的脆弱性降低来改善未来的死亡率估计。
我们使用来自 208 个美国城市的历史死亡率和温度数据，量化了从 1973 年到 2013 年观察到的脆弱性变化如何影响各种气候情景下与温度相关的死亡率预测。我们使用地理结构的荟萃回归来描述这段时间内这些城市人口中温度与死亡率之间的关系。然后，我们利用拟合的关系来预测未来气候条件下的死亡率。
在 2018 年 10 月 26 日至 2020 年 3 月 9 日期间，我们发现对温度的脆弱性存在地理结构差异。在大多数地区，脆弱性随时间的推移而降低。与使用 1973-82 年数据相比，当使用 2003-13 年数据时，美国因平均温度升高 2°C 而预测的死亡率下降了 97%以上。然而，这些好处随着温度的升高而减少，当温度升高 6°C 时，仅根据 2003-13 年的数据，预测的死亡率就下降了 84%。
即使考虑到适应因素，气候变化对过早死亡的预计影响也构成了一个重大的公共卫生风险。我们的研究表明，温度的大幅升高将需要额外的缓解措施，以避免因高温事件而导致的超额死亡，即使在已经有大量空调覆盖的地区也是如此。
美国环境保护署和 Abt 协会。
