A non-parametric study of temperature trends in Fiji over five decades

Abstract Small island developing states (SIDS) like Fiji are highly vulnerable to climate change, yet long-term, localized analyses of temperature trends remain limited. This study investigates annual mean minimum (Tmin), maximum (Tmax) and average (Tavg) temperature trends across 23 meteorological stations in Fiji over the period of 1970–2023, using the Mann–Kendall (MK) test, its modified variant (modified MK (MMK)) for accounting for autocorrelation and the Sen slope (SS) estimator. The results reveal widespread and statistically significant warming, with 57% of stations showing increases in minimum temperature (e.g. Vunisea: 0.33∘C per decade; Laucala: 0.30∘C per decade) and 78% in maximum temperature (e.g. Navua: 0.61∘C per decade; Viwa: 0.55∘C per decade). A majority of the stations (91%) recorded rising average temperatures, with the strongest warming observed in coastal and low-lying regions. Tmax exhibited the most intense warming at specific locations (e.g. Viwa, Yasawa, Navua), while Tmin showed more spatially consistent moderate increases across the country. Tavg trends fell between these two extremes, reflecting combined effects. The MMK test confirmed the robustness of the trends, while the SS estimator showed that Fiji’s warming rates exceeded global and regional benchmarks. These findings underscore the urgency of implementing adaptation measures in climate-sensitive sectors, prioritizing the highest-warming stations and providing a critical evidence base for policy development and improved climate monitoring in SIDS.