A New Evaluation of the Role of Urbanization to Warming at Various Spatial Scales: Evidence From the Guangdong‐Hong Kong‐Macau Region, China

Abstract

The urbanization impacts on surface air temperature (SAT) change in the Guangdong-Hong Kong-Macau region (GHMR) from 1979 to 2018 are examined using homogeneous surface observations, reanalysis, and remote sensing. Results show that the warming due to urbanization tends to be smaller or insignificant as the spatial scale increases. The urbanization contribution to the local warming can reach as high as 50% in the center of each metropolis, remains high (~25%) in the Greater Bay Area (GBA), and decreases to about 10% in the whole GHMR. The warming in GHMR is nearly uniform throughout the day, and therefore, the observed trend of the diurnal temperature range (DTR) is not statistically significant. However, the urbanization contribution exhibits distinct seasonal variations, large in summer and autumn while smaller in winter and spring. Plain Language Summary The Guangdong-Hong Kong-Macau region (GHMR), especially the Greater Bay Area (GBA), is a region typical of China's economic development and rapid urbanization. To precisely assess how much the urbanization contributes to the regional warming, we comprehensively evaluate the urbanization warming and its uncertainties in GHMR by using more careful processed and assessed data (observations, reanalysis, and remote sensing) and different analysis methods. The results show that the warming due to urbanization tends to be smaller as the spatial scale increases: The contribution to the local warming can reach as high as 50% in the metropolis, remains high (~25%) in GBA, and decreases to about 10% in GHMR. In addition, this paper systematically discusses the uncertainty in urbanization contribution detection, which was often neglected in the past detection. Based on the significance tests, urbanization warming is nearly uniform throughout the day, while it exhibits distinct seasonal variation. Our study also has important implications for understanding the influences of human activities on regional climate change for other regions experiencing rapid urbanization processes.

More Persistent Summer Compound Hot Extremes Caused by Global Urbanization

“…For example, Lin et al (2020) found that urbanization contributes about 30% of the change in extreme temperature events in urban areas across China. The inconformity might be explained by the existing phenomenon that urbanization contribution tends to be smaller as the spatial scale increase (Chao et al, 2020 To examine the regional differences in the magnitude of urbanization effects, the spatial patterns of urbanization contributions to the changes in CoHot and DayHot characteristics at regional grid scale are shown in Figure 3. The urbanization effects on hot extremes show regional variations, while relatively coherent distributions for the three characteristics of each type of hot extreme are observed.…”

Impact of Urbanization on Sunshine Duration from 1987 to 2016 in Hangzhou City, China

“…To avoid the impact of inhomogeneities in the SSD time-series on analysis results caused by station relocation, we only selected meteorological stations that have not been relocated. We selected stations with records covering the period 1987-2016, which is a period of solar brightening [12], dramatic warming [20], and rapid urbanization in China [32]. A total of five stations located near Hangzhou City were selected for this study (Figure 1).…”

“…In general, the impacts of urbanization on climate change can be estimated by comparing the difference between the climatic time-series of urban and rural stations [18][19][20]. This method referred to as urban minus rural (UMR), has been frequently applied in previous urban warming research, with relatively effective and reliable results [21,22].…”

A New Method for Correcting Urbanization-Induced Bias in Surface Air Temperature Observations: Insights From Comparative Site-Relocation Data

“…However, in reality, the urbanization processes at different times and in different regions are variable, so it is impossible to subdivide the specific degree of contribution of the urbanization bias to the SAT series on temporal and spatial scales. In addition, there are considerable differences in the mechanisms and magnitudes of the impact of urbanization on different temperature elements (Li et al, 2014), despite the possibly limited contribution to regional warming (Chao et al, 2020), while its impact on extreme temperatures are huge (Li and Huang, 2013;Li et al, 2014;Zhou et al, 2019).…”