Urbanization Effects on Human-Perceived Temperature Changes in the North China Plain

Feiyu Wang,Lei Zou,Keqin Duan

doi:10.3390/su11123413

Abstract

Urbanization and associated land use changes significantly alter the energy and radiation balance, land surface characteristics, and regional climates, posing challenges to natural ecosystems and human society. The combined effects of changes in air temperature (T), relative humidity (RH), and wind speed (WS) profoundly influence human-perceived temperature and the corresponding human thermal comfort, especially in urban areas with large population. This study analyzes the spatiotemporal changes in human-perceived temperatures in the North China Plain, represented by heat index (HI) in summer and wind chill temperature (WCT) in winter, and quantifies the effects of urbanization on temperature changes, based on the observational data of 56 meteorological stations during 1976–2016. The results show a significant warming trend, with human-perceived temperatures increasing faster than T. The warming trend in WCT is higher than that in HI, indicating more thermal discomfort in summer and more thermal comfort in winter. However, the warming trend moderately slows after 1996, partly due to the global surface warming hiatus. Urban areas experience stronger warming trends than non-urban areas, demonstrating the notable effects of urbanization. For the entire study area, urbanization and associated urban land expansion accelerate the increase in HI by 26% and the increase in WCT by 17%.

Highlights

Human beings are currently experiencing an unprecedented rate of urbanization and population growth [1,2,3]
Almost all the stations (i.e., 98.2% for heat index (HI), 94.6% for summer T, 98.2% for wind chill temperature (WCT), and 100% for winter T) show positive trends in the different temperature indicators, and most of these trends are statistically significant at the 5% level
The increasing trend in HI (0.35 ◦C per decade) is larger than that in T (0.25 ◦C per decade), suggesting that heat stress perceived by humans increases faster than the actual air temperature

Summary

Introduction

Human beings are currently experiencing an unprecedented rate of urbanization and population growth [1,2,3]. 55% of the global population lives in urban area, and this number is predicted to reach 68% by 2050 [4]. In the context of global warming and rapid urban expansion, people are facing rising hazards of extreme climate events, including heat waves, cold events, droughts, storms, and floods [5]. Extreme hot or cold events pose threats to humans, especially outdoor workers, women, children, the elderly, and persons with chronic disease [6,12,13]. Compared to suburban and rural areas, urban areas with dense population are prone to more serious threats induced by temperature [1,14,15]

Objectives

Methods

Results