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

Abstract

Surface temperatures are generally higher in cities than in rural surroundings 1 . This phenomenon, known as surface urban heat island (SUHI), increases the risk of heat-related human illnesses and mortality 2 . Past global studies analysed this phenomenon aggregated at city scale or over seasonal and annual time periods [3][4][5][6] , 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 as urban-rural surface temperature differences. 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 warmseason medians, and averaged worldwide are now 1.04 K or 31% higher compared to 2003. This can be linked with increasing urbanisation 7 , more frequent heatwaves 8 , and greening of the earth 9 , processes that are all expected to continue in the coming decades [10][11][12] . Within many cities there are hotspots where extreme SUHI intensity is 10 to 15 K higher compared to relatively cooler city parts. Given the limited human adaptability to heat stress 13 , our results advocate for mitigation strategies targeted at reducing SUHI extremes in the most vulnerable and exposed city neighbourhoods.

Lower Urban Humidity Moderates Outdoor Heat Stress

“…These results weaken a common premise in many previous studies where increased urban T s is expected to indicate adverse urban impact on overall heat vulnerability (Hsu et al, 2021;L. Zhao et al, 2017;Manoli et al, 2019;Mentaschi et al, 2022).…”

“…Coarse to medium-resolution T s from satellites have been used for hotspot analysis within cities (Hulley et al, 2019;Maimaitiyiming et al, 2014;Mentaschi et al, 2022). Several studies have taken advantage of the spatial continuity of satellite observations to map intra-urban variability of T s across cities with implications for environmental disparities (Benz & Burney, 2021;Hsu et al, 2021).…”

Exploring the Predictive Potential of Physiological Measures of Human Thermal Strain in Outdoor Environments in Hot and Humid Areas in Summer—A Case Study of Shanghai, China

“…In some places such as the US, the proportion of urban population is greater than 80% [ 1 ]. However, the way cities have been developed in the past has made them hotter than the surroundings [ 2 ]. This exacerbates the global trend toward a warmer climate and puts human health at risk.…”

Responses in thermal tolerance and daily activity rhythm to urban stress in Drosophila suzukii

“…Urban environments are typical hotspots for human activity, leading to the alteration of several habitats. Cities experience changes in abiotic factors, such as warming (Mentaschi et al, 2022 ; Simwanda et al, 2019 ; Tran et al, 2017 ), increased noise (Swaddle et al, 2015 ), light (Duque et al, 2019 ; Gaston et al, 2013 ), and chemical pollution (Castells‐Quintana et al, 2021 ; Han et al, 2014 ), as well and biotic factors, such as habitat fragmentation and shrinking, due to the development of artificial structures (Liu et al, 2016 ). These changes affect the ecological dynamics of the regional populations and communities (Achury et al, 2021 ; Hamer et al, 2021 ; Hung et al, 2019 ).…”