Urban Climates and Climate Change

Abstract

Cities are particularly vulnerable to extreme weather episodes, which are expected to increase with climate change. Cities also influence their own local climate, for example, through the relative warming known as the urban heat island (UHI) effect. This review discusses urban climate features (even in complex terrain) and processes. We then present state-of-the-art methodologies on the generalization of a common urban neighborhood classification for UHI studies, as well as recent developments in observation systems and crowdsourcing approaches. We discuss new modeling paradigms pertinent to climate impact studies, with a focus on building energetics and urban vegetation. In combination with regional climate modeling, new methods benefit the variety of climate scenarios and models to provide pertinent information at urban scale. Finally, this article presents how recent research in urban climatology contributes to the global agenda on cities and climate change. Expected final online publication date for the Annual Review of Environment and Resources, Volume 45 is October 19, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Global long-term mapping of surface temperature shows intensified intra-city urban heat island extremes

“…The more pronounced trend in 1 compared to suggests a higher sensitivity of extreme SUHI to urbanisation. Current understanding does not indicate that global warming directly enhances differences in rural-urban warming 22 , but the observed increase in heatwave days almost everywhere since the 1950s 8 and possible synergies between heat waves and SUHI 33 can partially explain the stronger increase in SUHI extremes. The amplification of greenness-climate feedbacks during extreme climate conditions 44 further suggests stronger positive effects of greening of non-urban areas on extreme SUHI compared to temporally-aggregated urban warming.…”

“…These findings confirm the important role of urban green and water in the mitigation of SUHI 17 . In coastal cities, proximity to the sea can mitigate 18 , as can be observed in Buenos Aires, Sydney and Jakarta, but sea breeze cooling effects can be inhibited by tall buildings on the seafront or inner city 22 .…”

“…Characterising temporal fluctuations is of foremost importance to assess the real threat posed to human health by urban heat, as phenomena such as heat waves can often last only few days [28][29][30] . Moreover, UHI intensity can vary between different parts of the same city 22 depending on their morphology and on the thermodynamic proprieties of their constitutive elements (e.g. densely built-up areas vs green areas).…”

The State-of-the-Art of Urban Climate Change Modeling and Observations

“…Only one very recent review paper has been published by Masson et al (2020) on urban climate and climate change. As a complement, in this review article, we present the state-of-the art of observations and modeling of the urban climate in Sects.…”

“…Sections 4 and 5 contain information about the observed urban climate trend and its interaction with global and regional-scale change, respectively. Section 6 provides a literature review of future urban climate under global climate change as a complement to Masson et al (2020). Sections 7 and 8 provide, respectively, information for two use case studies, one for the city of Brussels (Belgium) and the other one for three Asian mega-cities representing both developed and developing countries.…”