Human behaviour change and its impact on urban climate: Restrictions with the G20 Osaka Summit and COVID-19 outbreak

Abstract

Here we explored human behaviour change impacts on urban climate during the G20 Osaka Summit and the coronavirus 2019 (COVID-19) outbreak. The G20 Summit was held in the Asian megacity of Osaka, Japan on 28–29 June 2019. Due to the G20 restrictions, the traffic count in the city centre was lower by 33% compared with that 1 week prior (the usual week). The urban/office area population was reduced by approximately 10%; however, the residential population increased by 1%. Here we estimate the impact of G20 restrictions on anthropogenic heat (QF) and surface air temperature using a regional climate model coupled with urban canopy and building energy models. The results showed that the daytime QF and air temperature decreased by 15.6 W land-m−2 and 0.05 °C, respectively, in commercial areas of the city. The method described here is expected to be useful for estimating the impacts of similar political events and more extensive stay-at-home restrictions due to the recent COVID-19 pandemic on urban climates. A simple estimation showed that the COVID-19 restrictions resulted in QF of 76.3 W land-m−2 and a 0.13 °C temperature reduction in urban areas, thus, three- to five-fold the impact of the G20 Summit.