Current and Future Climate of the Fiji Islands

Rotuma eef a R Se at re Ahau G p u ro G a w a Vanua Levu s Bligh Water Taveuni N a o Y r th er Koro n La u G ro Koro Sea up Nadi Viti Levu SUVA Ono-i-lau S ou th er n L Kadavu au Gr South Pacific Ocean oup Current and future climate of the Fiji Islands > Fiji Meteorological Service > Australian Bureau of Meteorology > Commonwealth Scientific and Industrial Research Organisation (CSIRO) Fiji’s current climate Across Fiji the annual average temperature is between 20-27°C. Changes Fiji’s climate is also influenced by the in the temperature from season to season are relatively small and strongly trade winds, which blow from the tied to changes in the surrounding ocean temperature. east or south-east. The trade winds bring moisture onshore causing heavy Around the coast, the average night- activity. It extends across the South showers in the mountain regions. time temperatures can be as low Pacific Ocean from the Solomon Fiji’s climate varies considerably as 18°C and the average maximum Islands to east of the Cook Islands from year to year due to the El Niño- day-time temperatures can be as with its southern edge usually lying Southern Oscillation. This is a natural high as 32°C. In the central parts near Fiji (Figure 2). climate pattern that occurs across of the main islands, average night- Rainfall across Fiji can be highly the tropical Pacific Ocean and affects time temperatures can be as low as variable. On Fiji’s two main islands, weather around the world. There are 15ºC. The country has two distinct Viti Levu and Vanua Levu, rainfall is two extreme phases of the El Niño- seasons – a warm wet season from strongly influenced by high mountain Southern Oscillation: El Niño and La November to April and a cooler dry peaks up to 1300 m. On the south- Niña. There is also a neutral phase. In season from May to October (Figure 1). eastern slopes of Viti Levu, near Suva, Suva, El Niño events tend to bring dry Much of Fiji’s rainfall is associated with the average annual rainfall is about seasons that are drier and cooler than the movement of the South Pacific 3000 mm. In contrast, the lowlands on normal, while La Niña events usually Convergence Zone which is closest the western side of Viti Levu, near Nadi, bring wetter than normal conditions. to Fiji in the wet season. This band of are sheltered by the mountains and heavy rainfall is caused by air rising have an annual average rainfall of 1800 over warm water where winds mm with a well-defined dry season converge, resulting in thunderstorm favourable to crops such as sugar cane. Floods and droughts Maximum temperature Average temperature Minimum temperature Sea surface temperature River flooding occurs almost every wet season and occasionally 35 35 Suva, Fiji 178.45°E, 18.15°S in the dry season during La Niña events. Major floods tend 400 to be associated with severe weather events, such as tropical 30 depressions and cyclones that 300 bring high intensity rainfall. Most meteorological droughts 25 since 1920 are associated 200 with El Niño events. Recent severe droughts occurred Temperature (ºC) Monthly rainfall (mm) in 1987, 1992, 1997-98, 20 2003 and 2010 (Figure 5). 100 0 15 Jan Apr JulOct Figure 1: Seasonal rainfall and temperature at Suva. Fiji Meteorological Service Fiji Meteorological 2003 drought, Yaqara, northern Viti Levu. 2 N H o N 20 o Federated States of Micronesia Palau Marshall Islands o n e I n t e r t r o p i c a l C o n v e r g e n c e Z Kiribati 10 o W a Nauru 0 r m p Tra de W inds o o l S o Papua New Guinea u M o t h Tu valu n Solomon Islands S s o P o East Timor o n a c i f i c C o n v e Samoa r g Vanuatu Fiji e n Niue c e S 10 Z o o To nga Cook Islands n e S 20 H o 0 500 1,000 1,500 2,000 30 Kilometres o E E E E E E E W W W W o o o o o o o o o o o 0 0 0 0 0 0 0 0 0 0 0 180 11 12 13 14 15 16 17 17 16 15 14 Figure 2: The average positions of the major climate features in November to April. The arrows show near surface winds, the blue shading represents the bands of rainfall convergence zones, the dashed oval shows the West Pacific Warm Pool and H represents typical positions of moving high pressure systems. Tropical 6 Tropical cyclones 11-yr moving average 5 cyclones 4 Tropical cyclones usually affect Fiji between November and April, 3 and occasionally in October 2 and May in El Niño years. In the 41-year period between 1 1969 and 2010, 70 tropical No. of tropical cyclones 0 cyclones passed within 400 km of Suva, an average of one to two cyclones per season. Over 1969/701971/72 1973/74 1975/76 1977/78 1979/80 1981/82 1983/84 1985/86 1987/88 1989/90 1991/92 1993/94 1995/96 1997/98 1999/00 2001/02 2003/04 2005/06 2007/08 2009/10 this period, cyclones occurred Figure 3: Number of tropical cyclones passing within 400 km of Suva. more frequently in El Niño years. Eleven-year moving average in purple. 3 Fiji’s changing climate Temperatures No rainfall change tide gauges are used to measure sea level. Satellite data indicate sea level have increased Data for Suva and Nadi Airport has risen in Fiji by about 6 mm per (Figure 5) since 1950 show no year since 1993. This is larger than the Annual maximum and minimum clear trends in annual or seasonal global average of 2.8–3.6 mm per year. temperatures have increased in both rainfall. Over this period, there This higher rate of rise may be partly Suva (Figure 4) and Nadi since 1950. has been substantial variation related to natural fluctuations that take In Suva, maximum temperatures in rainfall from year to year. place year to year or decade to decade have increased at a rate of 0.15°C caused by phenomena such as the per decade and at Nadi Airport the El Niño-Southern Oscillation. The natural rate of increase has been 0.18°C Sea level has risen variation in sea level can be seen in per decade. These temperature As ocean water warms it expands Figure 7 which includes the tide gauge increases are consistent with the causing the sea level to rise. The record since 1972 and the satellite data global pattern of warming. melting of glaciers and ice sheets since 1993. also contributes to sea-level rise. Instruments mounted on satellites and Ocean acidification has been increasing 27 El Niño La Niña About one quarter of the carbon dioxide 26.5 emitted from human activities each year is absorbed by the oceans. As the extra 26 carbon dioxide reacts with sea water 25.5 it causes the ocean to become slightly more acidic. This impacts the growth emperature (ºC) T 25 of corals and organisms that construct their skeletons from carbonate minerals. 24.5 These species are critical to the balance Average of tropical reef ecosystems. Data 24 show that since the 18th century the 23.5 level of ocean acidification has been slowly increasing in Fiji’s waters. 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Year Figure 4: Annual average temperature for Suva. Light blue bars indicate El Niño years, dark blue bars indicate La Niña years and the grey bars indicate neutral years. 3500 El Niño La Niña 3000 2500 2000 1500 Rainfall (mm) 1000 500 0 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Year Figure 5: Annual rainfall for Nadi Airport. Light blue bars indicate El Niño Taking rainfall observations, years, dark blue bars indicate La Niña years and the grey bars indicate Laucala Bay Meteorology Office. neutral years. 4 Fiji’s future climate Climate impacts almost all aspects of life in Fiji. Understanding the possible future climate of Fiji is important so people and the government can plan for changes. How do scientists develop climate projections? Global climate models are the best tools or scenarios, in climate models. The for understanding future climate change. Intergovernmental Panel on Climate Climate models are mathematical Change (IPCC) developed a series of representations of the climate system plausible scenarios based on a set of that require very powerful computers. assumptions about future population They are based on the laws of physics changes, economic development and 2090 and include information about the technological advances. For example, 800 atmosphere, ocean, land and ice. the A1B (or medium) emissions scenario envisages global population peaking 2055 700 There are many different global climate 600 mid-century and declining thereafter, 2030 tion (ppm) models and they all represent the a r very rapid economic growth, and t climate slightly differently. Scientists from 1990 500 n rapid introduction of new and more e the Pacific Climate Change Science 400 c efficient technologies. Greenhouse on Program (PCCSP) have evaluated 24 C 300 gas and aerosol emissions scenarios 2 models from around the world and O are used in climate modelling to found that 18 best represent the climate C provide projections that represent of the western tropical Pacific region.

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