Current and Future Climate of Kiribati
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Washington Butaritari North Pacific Ocean Fanning Kiritmati (Christmas Island) Tarawa BAIRIKI Abemama Nonouti Tabiteuea Nikunau Winslow Arorae Gilbert Islands Phoenix Is. Nikumaroro Malden Carondelet Starbuck Line Islands Vostok Caroline South Pacific Ocean Flint Current and future climate of Kiribati > Kiribati Meteorology Service > Australian Bureau of Meteorology > Commonwealth Scientific and Industrial Research Organisation (CSIRO) Kiribati’s current climate Kiribati has a hot, humid tropical climate, with air temperatures very closely related to the temperature of the oceans surrounding the small islands and Droughts atolls. Across Kiribati the average temperature is relatively constant year round. Droughts can be very severe Changes in the temperature from season to season are no more than about 1°C. in Kiribati, and are usually associated with La Niña The driest and wettest periods in the rainfall are caused by air rising over events. Average annual rainfall year vary from location to location. warm water where winds converge, in Kiribati is approximately At Tarawa, in the west, the driest six- resulting in thunderstorm activity. 2100 mm with just over month period begins in June, with 900 mm received between May Kiribati’s climate varies considerably the lowest mean rainfall in October. and October. From July 1988 to from year to year due to the El Niño- The wet season usually lasts from December 1989 only 205 mm Southern Oscillation. This is a natural around November to April. At Kiritmati, of rain fell, while from August climate pattern that occurs across 2000 km to the east, the wet season 1998 to February 1999 total the tropical Pacific Ocean and affects is from January to June (Figure 1). rainfall was 95 mm. The recent weather around the world. There are two drought from April 2007 to early Rainfall in Kiribati is affected by extreme phases of the El Niño-Southern 2009 severely affected water the movement of the South Pacific Oscillation: El Niño and La Niña. There supplies in the southern Gilbert Convergence Zone and the Intertropical is also a neutral phase. Across Kiribati, Islands and Banaba. During this Convergence Zone. They extend El Niño events tend to bring wetter, period groundwater became across the South Pacific Ocean from warmer conditions than normal. In the brackish and the leaves of the Solomon Islands to east of the wettest years Tarawa has received more most plants turned yellow. Cook Islands, and across the Pacific than 4000 mm, while in the driest years just north of the equator, respectively as little as 150 mm of rain has fallen. (Figure 2). These bands of heavy Maximum temperature Average temperature Minimum temperature Sea surface temperature 35 35 300 Tarawa, Kiribati, 172.92ºE, 1.35ºN 300 Kiritimati, Kiribati, 157.48ºW, 1.98ºN 250 250 30 30 200 200 25 25 150 150 Temperature (ºC) Temperature (ºC) 100 Monthly rainfall (mm) 100 Monthly rainfall (mm) 20 20 0 50 05 15 0 15 Jan Apr Jul Oct Jan Apr Jul Oct Figure 1: Seasonal rainfall and temperature at Tarawa and Kiritimati. 2 and H represents typical positions of moving high pressure systems. typicalpositionsofmovinghighpressure and Hrepresents Warm Pool Pacific zones,thedashedovalshowsWest thebandsofrainfallconvergence the blueshadingrepresents 2: Figure Kiribati Meteorology Service. Kiribati Meteorology Climate datamanagementtraining, 110oE The average positions of the major climate features in November to April. The arrows shownearsurfacewinds, inNovembertoApril.Thearrows Theaveragepositionsofthemajorclimatefeatures 120oE M East o Timor 130oE n s Palau o I 140oE o n W Papua Ne n t a e r Fe m r w Guine 150oE derated StatesofMic t p r a o o o p l o 160 E i Solomon Islands c ro Lagoon Beachatlowtide,SouthTarawa. nesia a S Naur l o Va o nuatu u u 170 E Marshall Islands C t h Kiribati o P n Fiji a H v Tu o c 180 valu e i f r i To c g ng Samoa e a C o 170 W Niue n o n H c 0 5001,0001,5002,000 v e e Tr r o 160 W g Z Cook Islands a e de o n c n W e e o inds 150 W Z Kilometre o n e s 140oW 3 30oS 20oS 10oS 0o 10oN 20oN Kiribati’s changing climate Temperatures Annual rainfall Sea level has risen have increased has increased As ocean water warms it expands causing the sea level to rise. The Annual and seasonal maximum and Data since 1951 for Kiritimati show a melting of glaciers and ice sheets minimum temperatures have increased clear incresing trend in annual and wet also contributes to sea-level rise. in Tarawa since 1950 (Figure 3). season rainfall (Figure 4), but no trend in Maximum temperatures have increased the dry season. At Tarawa, rainfall data Instruments mounted on satellites and at a rate of 0.18°C per decade. These show no clear trends. Over this period, tide gauges are used to measure sea temperature increases are consistent there has been substantial variation in level. Satellite data indicate the sea level with the global pattern of warming. rainfall from year to year at both sites. has risen across Kiribati by 1–4 mm per year since 1993, compared to the global average of 2.8–3.6 mm per year. Sea level rise naturally fluctuates from year to 29.5 El Niño La Niña year and decade to decade as a result 29 of phenomena such as the El Niño- Southern Oscillation. This variation in 28.5 sea level can be seen in Figure 6 which includes the tide gauge record since 28 1950 and satellite data since 1993. emperature (ºC) T 27.5 Ocean acidification 27 Average has been increasing 26.5 About one quarter of the carbon dioxide 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 emitted from human activities each year Year is absorbed by the oceans. As the extra Figure 3: Annual average temperature for Tarawa. Light blue bars indicate carbon dioxide reacts with sea water El Niño years, dark blue bars indicate La Niña years and the grey bars it causes the ocean to become slightly indicate neutral years. more acidic. This impacts the growth of corals and organisms that construct their skeletons from carbonate minerals. 4000 El Niño La Niña These species are critical to the balance 3500 of tropical reef ecosystems. Data 3000 show that since the 18th century the level of ocean acidification has been 2500 slowly increasing in Kiribati’s waters. 2000 Rainfall (mm) 1500 1000 500 0 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Year Figure 4: Annual rainfall for Kiritmati. Light blue bars indicate El Niño years, dark blue bars indicate La Niña years and the grey bars indicate neutral years. Taking temperature observations, Kiribati Meteorology Service. 4 Kiribati’s future climate Climate impacts almost all aspects of life in Kiribati. Understanding the possible future climate of Kiribati is important so people and the government can plan for changes. How do scientists develop climate projections? Global climate models are the best tools Intergovernmental Panel on Climate for understanding future climate change. Change (IPCC) developed a series of Climate models are mathematical plausible scenarios based on a set of representations of the climate system assumptions about future population that require very powerful computers. changes, economic development and They are based on the laws of physics technological advances. For example, 2090 and include information about the the A1B (or medium) emissions scenario 800 atmosphere, ocean, land and ice. envisages global population peaking mid-century and declining thereafter, 2055 700 There are many different global climate 600 very rapid economic growth, and 2030 tion (ppm) models and they all represent the a r rapid introduction of new and more t climate slightly differently. Scientists from 1990 500 n efficient technologies. Greenhouse e the Pacific Climate Change Science 400 c gas and aerosol emissions scenarios on Program (PCCSP) have evaluated 24 C 300 are used in climate modelling to 2 models from around the world and O provide projections that represent found that 18 best represent the climate C a range of possible futures. of the western tropical Pacific region. Figure 5: Carbon dioxide (CO2) These 18 models have been used to The climate projections for Kiribati concentrations (parts per million, ppm) develop climate projections for Kiribati. are based on three IPCC emissions associated with three IPCC emissions scenarios: low (B1), medium (A1B) scenarios: low emissions (B1 – blue), The future climate will be determined and high (A2), for time periods medium emissions (A1B – green) and by a combination of natural and human around 2030, 2055 and 2090 high emissions (A2 – purple). The factors. As we do not know what the (Figure 5). Since individual models PCCSP has analysed climate model future holds, we need to consider a give different results, the projections results for periods centred on 1990, range of possible future conditions, are presented as a range of values. 2030, 2055 and 2090 (shaded). or scenarios, in climate models. The Taking temperature observations, Kiribati Meteorology Service. Aerial view, South Tarawa. 5 Kiribati’s future climate This is a summary of climate projections for Kiribati. For further information refer to Volume 2 of Climate Change in the Pacific: Scientific Assessment and New Research, and the web-based climate projections tool – Pacific Climate Futures (available at www.pacificclimatefutures.net). Temperature will Changing rainfall continue to increase patterns Projections for all emissions scenarios Almost all of the global climate indicate that the annual average models project an increase in air temperature and sea surface average annual and seasonal rainfall temperature will increase in the over the course of the 21st century.