Responses of extreme high temperatures to urbanization in the Beijing–Tianjin–Hebei urban agglomeration in the context of a changing climate

Abstract

AbstractExtreme high‐temperature event is one of the most urgent climate issues faced by coordinated development of the Beijing–Tianjin–Hebei region (BTH) in the future due to global warming and urbanization. Based on the homogenized daily temperatures from 174 meteorological observation stations, six extreme hot events were detected. The results revealed the spatiotemporal change characteristics of the extreme high temperature in the BTH. The acquired evidence showed the maximum daily minimum temperature (TNx), high‐temperature days (SU35), hot night days (TR25), and heatwave spell durations (HWDI) have significantly increased, while the daily temperature range (DTR) has significantly decreased (p < 0.01) during 1961–2018. The SU35, TR25 and HWDI in 2010s were 68%, 2.8 times and 2.1 times higher than that in 1980s, respectively. Moreover, since 1961, the high‐temperature season in the BTH has been getting longer at a rate of 7.4d/10a. The study also revealed the contribution of urbanization on high‐temperature indices depends on city size and location in the BTH. The magnitudes of the indices change in the downtown area of Beijing, Tianjin and Shijiazhuang ranked top in the 13 cities of the BTH, which are closely related to the urban development. The mean contribution of urbanization on maximum daily maximum temperature (TXx), TNx, SU35 and TR25 was 68%, 45% and 27% in Beijing, Tianjin and Shijiazhuang, respectively. The socio‐economic driving factors have an important impact on the change rates of the extreme high‐temperature indices, which means that controlling population, city size and reducing energy consumption could effectively alleviate the urban heat island (UHI) effect and slow down the high‐temperature events in the BTH. In the future, it is vital to further study and investigate the mechanism of the extreme high‐temperature changes through numerical simulations and to research their impact and response in this region.