The Intensity of Surface Urban Heat Islands in the Global North during the COVID-19 Lockdowns

To curtail the rapid spread of the Coronavirus Disease 2019 (COVID-19), governments worldwide introduced stay-at-home and business closure orders that caused an unprecedented reduction in human and industrial activities. This work aims to evaluate the effect of these extreme containment policies on the Surface Urban Heat Island Intensity (SUHII) of cities in China, the European Union (EU27), and the United States of America (USA), by assessing how nighttime SUHII changed during the first pandemic wave of spring 2020 compared to 2010- 2019. Our results reveal a substantial decrease in the SUHII of Chinese cities (-0.4 K) that we attribute to the strict lockdown measures imposed by the government. In contrast, the results for EU27 (+0.2 K) and USA (-0.2 K) are comparable to the inter-annual SUHII range of the reference period. Our findings support the thesis that lockdowns influenced the urban climate but also hint that this effect may not be detectable or present everywhere.