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

• Published in: Global environmental change 2022-01, Vol.72, p.102441, Article 102441
• Main Authors: Mentaschi, Lorenzo, Duveiller, Grégory, Zulian, Grazia, Corbane, Christina, Pesaresi, Martino, Maes, Joachim, Stocchino, Alessandro, Feyen, Luc
• Format: Article
• Language: English
• Subjects: Adaptability; Cities; data collection; Extremes; global change; Global scale; Heat; heat island; Heat stress; Heat tolerance; High space–time resolution; Human influences; Humans; Long-term; Mapping; Mitigation; mortality; Neighborhoods; risk; Rural communities; space and time; SUHI; Surface temperature; Temperature gradients; Trends; Urban areas; Urban Heat Island; Urban heat islands; Urbanization; warm season
• ISSN: 0959-3780; 1872-9495
• DOI: 10.1016/j.gloenvcha.2021.102441

•We developed a global, consistent high space–time resolution dataset of SUHI.•Our data offer a global insight into the space–time variability of SUHI.•We found high variability of SUHI, with 3-day maxima much higher than seasonal medians.•The intensity of extreme SUHI is increasing worldwide, faster than the median SUHI. Surface temperatures are generally higher in cities than in rural surroundings. This phenomenon, known as Surface Urban Heat Island (SUHI), increases the risk of heat-related human illnesses and mortality. Past global studies analysed this phenomenon aggregated at city scale or over seasonal and annual time periods, while human impacts strongly depend on shorter term heat stress experienced locally. Here we develop a global long-term high-resolution dataset of daytime SUHI, offering an insight into the space–time variability of the urban–rural temperature differences which is unprecedented at global scale. Our results show that across urban areas worldwide over the period 2003–2020, 3-day SUHI extremes are on average more than twice as high as the warm-season median SUHI, with local exceedances up to 10 K. Over this period, SUHI extremes have increased more rapidly than warm-season medians, and averaged worldwide are now 1.04 K or 31% higher compared to 2003. This can be linked with increasing urbanisation, more frequent heatwaves, and greening of the earth, processes that are all expected to continue in the coming decades. Within many cities there are hotspots where extreme SUHI intensity is 10–15 K higher compared to relatively cooler city parts. Given the limited human adaptability to heat stress, our results advocate for mitigation strategies targeted at reducing SUHI extremes in the most vulnerable and exposed city neighbourhoods.