Persistent Increases in Nighttime Heat Stress From Urban Expansion Despite Heat Island Mitigation
Persistent Increases in Nighttime Heat Stress From Urban Expansion Despite Heat Island Mitigation
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DOI：
10.1029/2020jd033831
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发表时间：
2021-02-27
影响因子：
4.4
通讯作者：
Seto, Karen C.
中科院分区：
文献类型：
--
作者：
Huang, Kangning;Lee, Xuhui;Seto, Karen C.
城市地区的近地表空气温度一般比农村地区高，空气湿度一般比农村地区低。关于高温和高湿对人体生理的综合影响--热应激将如何受到未来城市土地扩张的影响，人们知之甚少。在这里，我们使用中尺度数值天气预报模型来研究2000年至2050年城市土地扩张对中国，印度和尼日利亚城市地区热应力（以湿球地球仪温度，WBGT测量）的影响，预计到2050年，这些城市将占全球城市人口增长的三分之一。我们的研究结果表明，城市扩张在白天略微降低了热应力（类似于0.2摄氏度），但在夜间却大大加剧了热应力，平均降低了1摄氏度，在五个特大城市地区（MURs）则高达2-3摄氏度。无论温室气体浓度上升是否引起气候变化，这些影响都存在。安装凉爽的屋顶-城市热岛缓解措施-可以将白天的WBGT降低0.5-1摄氏度，部分抵消温室气体引起的气候变化造成的热应力条件。然而，即使有凉爽的屋顶，与城市地区保持不变的情况相比，在所研究的整个国家中，夜间WBGT也要高出0.3-0.9摄氏度，而在城市扩张情景下，MUR要高出1-2摄氏度。这些结果表明，未来的城市扩张和热岛缓解可能会带来潜在的白天效益，但也会带来持续的夜间风险。
Urban areas generally have higher near-surface air temperature and lower air humidity than rural areas. Little is known about how heat stress, the combined effect of high air temperature and high humidity on human physiology, will be affected by future urban land expansion. Here we use a mesoscale numerical weather prediction model to examine the effects of urban land expansion from 2000 to 2050 on heat stress (measured as wet-bulb globe temperature, WBGT) in the urban areas of China, India, and Nigeria, which are projected to account for one-third of global urban population growth through 2050. Our results show that urban expansion slightly reduces heat stress during the day (similar to 0.2 degrees C) but substantially intensifies it at night, by similar to 1 degrees C on average and by up to 2-3 degrees C in five mega-urban regions (MURs). These effects exist with or without climate change induced by rising concentrations of greenhouse gases (GHGs). Installing cool roofs-an urban heat island mitigation measures-can reduce the daytime WBGT by 0.5-1 degrees C, partially offsetting the heat stress conditions caused by GHG-induced climate change. However, even with cool roofs, the nighttime WBGTs are higher by 0.3-0.9 degrees C over the whole countries studied, and by 1-2 degrees C in the MURs under the urban expansion scenario, compared to the situation in which urban areas remain unchanged. These results show that future urban expansion and heat island mitigation can result in potential daytime benefits but also persistent nighttime risks.