Variability of temperature and heatwaves in the South Pacific Islands region under global warming

Sagero, Philip and Kumar, Nilesh and Ongoma, Victor and Sian, Kenny T. (2025) Variability of temperature and heatwaves in the South Pacific Islands region under global warming. Theoretical and Applied Climatology, 156 (644). pp. 1-21. ISSN 0177-798X

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Abstract

Global warming is intensifying temperature extremes across the South Pacific Islands, yet heatwave-specific studies in this region remain limited. This study investigates the trends in temperature extremes focusing on heatwaves from 1981 to 2024. The study is based on ERA5 reanalysis data for 22 station locations across Vanuatu, Fiji, The Solomon Islands, Tuvalu, and New Caledonia. Daily maximum (Tmax) and minimum (Tmin) temperatures were analyzed with percentile-based indices and heatwave metrics (number, frequency, duration), with heatwave defined as three or more consecutive days exceeding the 90th percentile of historical data based on the 1991–2020 climatological baseline. Trends were assessed using the Sen’s slope estimator and Mann-Kendall test, while heat stress was quantified using humidity index (HD). Results show significant warming, with Tmax increasing by 0.015–0.023 °C/year and Tmin by 0.009–0.025 °C/year. Heatwave frequency increased markedly, notably in Tuvalu (peaking at 27 events in 2023) and the Solomon Islands (20 in 2024), with duration and intensity also increasing, particularly in equatorial locations. Heat stress was consistently elevated, with perceived temperatures (23–34 °C) often exceeding actual Tmax due to high humidity. Urban areas such as Nadi in Fiji, exhibit faster Tmin increases than Tmax, suggesting urban heat island effects that may be intensifying local heat stress. These findings highlight the need for targeted adaptation strategies, including improved early warning systems and urban planning, to build resilience in this highly vulnerable region.

Item Type:	Journal Article
Uncontrolled Keywords:	Global warming, Thermal health, Sustainable Development Goals, Urbanization
Subjects:	G Geography. Anthropology. Recreation > GB Physical geography
Divisions:	School of Agriculture, Geography, Environment, Ocean and Natural Sciences (SAGEONS)
Depositing User:	Philip Sagero
Date Deposited:	08 Dec 2025 03:33
Last Modified:	08 Dec 2025 03:33
URI:	https://repository.usp.ac.fj/id/eprint/15203

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