TY - JOUR
T1 - Spatio-temporal development of the urban heat island in a socioeconomically diverse tropical city
AU - Ramsay, Emma E.
AU - Duffy, Grant A.
AU - Burge, Kerrie
AU - Taruc, Ruzka R.
AU - Fleming, Genie M.
AU - Faber, Peter A.
AU - Chown, Steven L.
N1 - Funding Information:
The RISE program is funded by the Wellcome Trust [OPOH grant 205222/Z/16/Z] , the New Zealand Ministry of Foreign Affairs and Trade, the Australian Department of Foreign Affairs and Trade , the Asian Development Bank , the Government of Fiji, the City of Makassar and Monash University , and involves partnerships and in-kind contributions from the Cooperative Research Centre for Water Sensitive Cities , Fiji National University, Hasanuddin University , Southeast Water, Melbourne Water , Live and Learn Environmental Education, UN-Habitat, UNU-IIGH, WaterAid International and Oxfam. E.E.R is supported by an Australian Government Research Training Program Scholarship. G.A.D. is the recipient of an Australian Research Council Discovery Early Career Researcher Award ( DE190100003 ) funded by the Australian Government . We thank the RISE Program Consortium (details of the RISE study can be found on the study website: www.rise-program.org/ ) for field data collection assistance and administrative support. Two anonymous reviewers are thanked for their insightful comments.
Publisher Copyright:
© 2022 The Authors
PY - 2023/1/1
Y1 - 2023/1/1
N2 - Urban heat islands, where temperatures are elevated relative to non-urban surrounds, are near-ubiquitous in cities globally. Yet, the magnitude and form of urban heat islands in the tropics, where heat has a large morbidity and mortality burden, is not well understood, especially for those of urban informal settlements. We used 29 years of Landsat satellite-derived surface temperature, corroborated by in situ temperature measurements, to provide a detailed spatial and temporal assessment of urban heat islands in Makassar, Indonesia, a city that is representative of rapidly growing urban settlements across the tropics. Our analysis identified surface urban heat islands of up to 9.2 °C in long-urbanised parts of the city and 6.3 °C in informal settlements, the seasonal patterns of which were driven by change in non-urban areas rather than in urban areas themselves. In recently urbanised areas, the majority of urban heat island increase occurred before land became 50% urbanised, whereas the established heat island in long-urbanised areas remained stable in response to urban expansion. Green and blue space protected some informal settlements from the worst urban heat islands observed across the city and maintenance of such space will be essential to mitigate the growing heat burden from urban expansion and anthropogenic climate change. Settlements further than 4 km from the coast and with Normalised Difference Vegetation Index (NDVI) less than 0.2 had higher surface temperatures, with modelled effects of more than 5 °C. Surface temperature measurements were representative of in situ heat exposure, measured in a subset of 12 informal settlements, where mean indoor temperature had the strongest relationship with surface temperature (R2 = 0.413, P = 0.001). We advocate for green space to be prioritised in urban planning, redevelopment and informal settlement upgrading programs, with consideration of the unique environmental and socioeconomic context of tropical cities.
AB - Urban heat islands, where temperatures are elevated relative to non-urban surrounds, are near-ubiquitous in cities globally. Yet, the magnitude and form of urban heat islands in the tropics, where heat has a large morbidity and mortality burden, is not well understood, especially for those of urban informal settlements. We used 29 years of Landsat satellite-derived surface temperature, corroborated by in situ temperature measurements, to provide a detailed spatial and temporal assessment of urban heat islands in Makassar, Indonesia, a city that is representative of rapidly growing urban settlements across the tropics. Our analysis identified surface urban heat islands of up to 9.2 °C in long-urbanised parts of the city and 6.3 °C in informal settlements, the seasonal patterns of which were driven by change in non-urban areas rather than in urban areas themselves. In recently urbanised areas, the majority of urban heat island increase occurred before land became 50% urbanised, whereas the established heat island in long-urbanised areas remained stable in response to urban expansion. Green and blue space protected some informal settlements from the worst urban heat islands observed across the city and maintenance of such space will be essential to mitigate the growing heat burden from urban expansion and anthropogenic climate change. Settlements further than 4 km from the coast and with Normalised Difference Vegetation Index (NDVI) less than 0.2 had higher surface temperatures, with modelled effects of more than 5 °C. Surface temperature measurements were representative of in situ heat exposure, measured in a subset of 12 informal settlements, where mean indoor temperature had the strongest relationship with surface temperature (R2 = 0.413, P = 0.001). We advocate for green space to be prioritised in urban planning, redevelopment and informal settlement upgrading programs, with consideration of the unique environmental and socioeconomic context of tropical cities.
KW - Cities
KW - Informal settlements
KW - Land cover change
KW - Landsat
KW - Remote sensing
KW - Tropics
KW - Urban heat islands
KW - Urbanisation
UR - https://www.scopus.com/pages/publications/85140469523
U2 - 10.1016/j.envpol.2022.120443
DO - 10.1016/j.envpol.2022.120443
M3 - Article
C2 - 36265725
AN - SCOPUS:85140469523
SN - 0269-7491
VL - 316
JO - Environmental Pollution
JF - Environmental Pollution
IS - Part 1
M1 - 120443
ER -
SDG 11 Sustainable Cities and Communities
SDG 13 Climate Action