The new village is now under threat of inundation and sea walls have to be constantly maintained. Photo: Justin McManus, The Age

Changing climate

Temperatures have increased

Annual and seasonal maximum temperatures have increased in Tarawa since 1950. Maximum temperatures have increased at a rate of 0.18 degrees Celsius per decade. These temperature increases are consistent with the global pattern of warming.

Figure 3: Annual average temperature for Tarawa. Light blue bars indicate El Nino years, dark blue bars indicate La Nina years and the grey bars indicate neutral years. Source: www.pacificclimatechangescience.org
Figure 3: Annual average temperature for Tarawa. Light blue bars indicate El Nino years, dark blue bars indicate La Nina years and the grey bars indicate neutral years.

Annual rainfall has increased

Data since 1951 for Kirimati show a clear increasing trend in annual and wet season rainfall, but no trend in annual and wet season rainfall, but no trend in the dry season. At Tarawa, rainfall data show no clear trends. Over this period, there has been substantial variation in rainfall from year to year at both sites.

Figure 4: Annual rainfall for Kiritimati. Light blue bars indicate El Nino years, dark blue bars indicate La Nina years and the grey bars indicate the neutral years. Source: www.pacificclimatechangescience.org

Figure 4: Annual rainfall for Kiritimati. Light blue bars indicate El Nino years, dark blue bars indicate La Nina years and the grey bars indicate the neutral years. Source: www.pacificclimatechangescience.orgSea level has risen

Sea level has risen

As ocean water warms it expands causing the sea level to rise, the melting of glaciers and ice sheets also contributes to sea-level rise.

Instruments mounted on satellites and tide gauges are used to measure sea level. Satellite data indicate the sea level has risen across Kiribati by 1 – 4mm 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 year and decade to decade as a result of phenomena such as the El Nino-Southern Oscillation.

Figure 6: Observed and projected relative sea-level change in Kiribati. The observed sea-level records are indicated in dark blue (relative tide-gauge observations) and light blue (satellite record since 1993). Reconstructed estimates of sea level near Kiribati (since 1950) are shown in purple. The projections for the A1B (medium) emissions scenario (representing 90% of the range of models) are shown by the shaded green region from 1990 to 2100. The dashed lines are an estimate of the 90% of the range of natural year-to-year variability in sea level.

Figure 6: Observed and projected relative sea-level change in Kiribati. The observed sea-level records are indicated in dark blue (relative tide-gauge observations) and light blue (satellite record since 1993). Reconstructed estimates of sea level near Kiribati (since 1950) are shown in purple. The projections for the A1B (medium) emissions scenario (representing 90% of the range of models) are shown by the shaded green region from 1990 to 2100. The dashed lines are an estimate of the 90% of the range of natural year-to-year variability in sea level.

Ocean acidification has been increasing

About one quarter of the carbon dioxide emitted from human activities each year is absorbed by the oceans. As the extra carbon dioxide reacts with sea water it causes the ocean to become slightly more acidic. This impacts the growth of corals and organisms that construct their skeletons from carbonate minerals. These species are critical to the balance of tropical reef ecosystems. Data show that since the 18th century the level of ocean acidification has been slowly increasing in Kiribati’s waters.

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Information on this page has been sourced on behalf of the Kiribati Meteorology Service and with kind permission from Australian Bureau of Meteorology and CSIRO, 2011.Current and future climate of Kiribati. Visit www.pacificclimatechangescience.org to download information brochures.

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