Communicating the deadly consequences of global warming for human heat stress
Communicating the deadly consequences of global warming for human heat stress
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DOI：
10.1073/pnas.1617526114
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发表时间：
2017-04-11
影响因子：
11.1
通讯作者：
Murphy, Conor
中科院分区：
文献类型：
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作者：
Matthews, Tom K. R.;Wilby, Robert L.;Murphy, Conor
2015年12月，国际社会承诺将全球变暖限制在比工业化前（PI）高2摄氏度以下，以防止危险的气候变化。然而，如果实现这一雄心勃勃的目标，在多大程度上以及对谁来说，危险得以避免？我们通过仔细研究热应激来解决这些问题，因为预计极端炎热天气的频率将继续上升，接近2摄氏度的限制。我们使用类似物和2015年南亚的极端高温作为焦点事件，以帮助解释在特定的全球变暖量下致命高温的频率增加。使用大量的气候模型，我们的研究结果证实，全球平均气温与热应力呈非线性关系，这意味着迄今为止实现的未来变暖可能会引发比历史上经历的更大的社会影响增加。这种非线性对于整合湿度上升的影响的热应力度量更高。我们表明，即使在比PI高2摄氏度的气候中，卡拉奇（巴基斯坦）和加尔各答（印度）每年都可能出现相当于2015年致命热浪的条件。全球变暖只有1.5摄氏度，两倍的特大城市（如拉各斯，尼日利亚和中国上海）可能会成为热压力，在中等人口增长情景下，到2050年将有超过3.5亿人面临致命的高温。这些结果强调，即使巴黎目标得以实现，城市弱势人口仍有必要采取重大的适应措施。
In December of 2015, the international community pledged to limit global warming to below 2 degrees C above preindustrial (PI) to prevent dangerous climate change. However, to what extent, and for whom, is danger avoided if this ambitious target is realized? We address these questions by scrutinizing heat stress, because the frequency of extremely hot weather is expected to continue to rise in the approach to the 2 degrees C limit. We use analogs and the extreme South Asian heat of 2015 as a focusing event to help interpret the increasing frequency of deadly heat under specified amounts of global warming. Using a large ensemble of climate models, our results confirm that global mean air temperature is nonlinearly related to heat stress, meaning that the same future warming as realized to date could trigger larger increases in societal impacts than historically experienced. This nonlinearity is higher for heat stress metrics that integrate the effect of rising humidity. We show that, even in a climate held to 2 degrees C above PI, Karachi (Pakistan) and Kolkata (India) could expect conditions equivalent to their deadly 2015 heatwaves every year. With only 1.5 degrees C of global warming, twice as many megacities (such as Lagos, Nigeria, and Shanghai, China) could become heat stressed, exposing more than 350 million more people to deadly heat by 2050 under a midrange population growth scenario. The results underscore that, even if the Paris targets are realized, there could still be a significant adaptation imperative for vulnerable urban populations.