Accelerating Urban Heating Under Land-Cover and Climate Change Scenarios in Indonesia: Application of the Universal Thermal Climate Index

Abstract

Climate change causing an increase of frequency and magnitude of heat waves has a huge impact on the urban population worldwide. In Indonesia, the Southeast Asian country in the tropical climate zone, the increasing heat wave duration due to climate change will be also magnified by projected rapid urbanization. Therefore, not only climate change mitigation measures but also adaptation solutions to more frequent extreme weather events are necessary. Adaptation is essential at local levels. The projected increase of the heat wave duration will trigger greater health-related risks. It will also drive higher energy demands, particularly in urban areas, for cooling. New smart solutions for growing urbanization for reducing urban heat island phenomenon are critical, but in order to identify them, analyzing the changing magnitude and spatial distribution of urban heat is essential. We projected the current and future spatial variability of heat stress index in three cities in Indonesia, namely, Medan, Surabaya, and Denpasar, under climate change and land-cover change scenarios, and quantified it with the Universal Thermal Climate Index (UTCI) for two periods, baseline (1981–2005) and future (2018–2042). Our results demonstrated that currently the higher level of the UTCI was identified in the urban centers of all three cities, indicating the contribution of urban heat island phenomenon to the higher UTCI. Under climate change scenarios, all three cities will experience increase of the heat, whereas applying the land-cover scenario demonstrated that in only Medan and Denpasar, the UTCI is likely to experience a higher increase by 3.1°C; however, in Surabaya, the UTCI will experience 0.84°C decrease in the period 2018–2042 due to urban greening. This study advanced the UTCI methodology by demonstrating its applicability for urban heat warning systems and for monitoring of the urban green cooling effect, as well as it provides a base for adaptation measures’ planning.

Extreme heat vulnerability assessment in Indonesia at the provincial level

“…Previous research has also revealed that high heat stress index values are concentrated primarily in the central and densely populated areas [2]. Moreover, owing to the UHI effects, urban areas experience higher land surface temperatures than rural areas [2,21]. Despite this, high heat exposure was observed on the east coast of North Sumatra, along the coast of East Java, and in the southern part of Bali.…”

“…Economic growth in sectors such as manufacturing, agriculture, and tourism has resulted in expanding urban areas in those regions. Previous research has also revealed that high heat stress index values are concentrated primarily in the central and densely populated areas [2]. Moreover, owing to the UHI effects, urban areas experience higher land surface temperatures than rural areas [2,21].…”

“…Despite having consistent temperatures throughout the year, tropical regions have begun to experience frequent extreme heat and it is projected that these areas will suffer from more heat stress than other regions due to high humidity levels [1]. reported that the heat stress index will increase by 1.9°C in Indonesia urban areas under the ensemble mean climate change scenario [2]. Furthermore, under the 90th percentile of climate change scenario, the extreme heat stress will be emerged in the Indonesia IOP Publishing doi:10.1088/1755-1315/1095/1/012021 2 megacities in the period of 2018-2042 [2].…”

“…reported that the heat stress index will increase by 1.9°C in Indonesia urban areas under the ensemble mean climate change scenario [2]. Furthermore, under the 90th percentile of climate change scenario, the extreme heat stress will be emerged in the Indonesia IOP Publishing doi:10.1088/1755-1315/1095/1/012021 2 megacities in the period of 2018-2042 [2]. The expected increase in the intense heat occurrences could rise heat-related illness and death among vulnerable population [3] including in the tropical countries.…”

Identifying Climate Change Vulnerability Based on Land Cover Indicators: A Case Study in Surabaya, Indonesia

“…Surabaya's urban park development program is one of the causes of this positive change in land use and cover. Setiawati et al (2021) reported that from 1995 to 2016 the bare land in the southwestern and central part of Surabaya was converted into green parks. Furthermore, the increase in minimum, average, and maximum surface temperatures in 2015 and 2019 is in line with the percentage of land use change into built-up areas (64%) supported by changes in water bodies and green areas to agricultural land at 6.5% and 4.9%, respectively.…”