Spatiotemporal variations of extreme temperature events and population exposure in Shandong Province from 1986 to 2022

Abstract

[Objective] In the context of global climate change, various disasters caused by extreme weather have become more frequent, recurrent, and severe. Understanding the variations of extreme temperature events and their population exposure holds great practical value for protecting people's lives and health, as well as for promoting economic and social development. [Methods] Using daily temperature observations, the spatiotemporal characteristics of extreme temperature events in Shandong Province from 1986 to 2022 were analyzed by using method including linear trend estimation, Mann-Kendall test, sliding t-test, and wavelet analysis. Combined with the national census data, the variation patterns of population exposure to extreme temperature at the county level in Shandong Province were revealed. [Results] (1) Temporally, the annual average number of high-temperature days in Shandong Province increased from 5.93 d to 12.49 d, with an increasing rate of 2.0 d/10 a(P<0.01), while the annual average number of frozen days showed a slight downward trend at a rate of 0.1 d/10 a.(2) Spatially, the annual average number of high-temperature days in Shandong Province gradually increased from east to west, and the annual average number of frozen days showed a distribution pattern of being higher in the north and lower in the south. Compared with the period from 1986 to 1995, the number of counties with an annual average number of high-temperature days exceeding 8 d increased by 227% during the period from 2013 to 2022, while no significant spatial changes were observed in the annual average number of frozen days.(3) From 1986 to 2022, the population exposure to extreme high temperature in Shandong Province increased continuously, with the annual average population exposure rising from 5.25 million people·d during the Fourth National Population Census to 12.57 million people·d during the Seventh National Population Census. Areas with high values were located in the southwestern and central Shandong. The population exposure to extreme low temperature first increased and then decreased, with high-value areas mainly distributed in the eastern Shandong Peninsula. [Conclusion] Both the frequency and influence range of extreme high-temperature events in Shandong Province have shown significant upward trends. Combined with changes in population size, the exposure to extreme high temperature increases rapidly, while extreme low-temperature events and their population exposure first increase and then decrease, with relatively small overall variations.

Keywords

extreme temperature / population exposure / spatiotemporal variation / Mann-Kendall test / county-level scale / influencing factors