Surface urban heat island effects intensify more rapidly in lower income countries
Yuan Yuan, Mattheos Santamouris, Dong Xu, Xiaolei Geng, Chengwei Li, Wanqing Cheng, Ling Su, Peng Xiong, Zhengqiu Fan, Xiangrong Wang, Chuan Liao
Abstract
As urbanization proceeds globally in recent decades, a nuanced understanding of the differential impacts of the urban heat island (UHI) effect across income country groups is crucial. Through an analysis of ~5 million urban grids from 2003 to 2018, we discovered that the average surface urban heat island intensity (SUHII) increased at a rate of 0.021 °C annually. Despite the extensive areas of SUHII increase in higher-income countries, particularly the US and China, it is the low and lower-middle-income countries that exhibited a more pronounced net increase in intensity. Specifically, 27% of urban grids in low-income countries witnessed the most substantial net increase during the daytime, while 19% of urban grids in lower-middle-income countries led the surge at nighttime. Higher-income countries’ SUHII growth reflects their pace of urbanization, but the trend of intensifying urban heat expands faster in lower-income economies. Such findings underscore an impending UHI challenge for lower-middle and low-income nations, emphasizing the need for targeted mitigation and adaptation strategies.