Regional Impacts - South Pacific

Observed change

• Annual and seasonal ocean  surface and air temperature increased by 0.6° to 1°C since 1910 in much of the Pacific.
• There has been a significant decrease in the annual number of cool days and cool nights, particularly after El Niño events, for the period 1961 to 2003.
• Sea level rise has varied across the region, ranging from 1.5 mm to more than 3mm per year.
• Tropical storm intensity has increased and a relationship between ENSO and the tracks, density and occurrence of cyclones has been observed (Walsh, 2004 cited in Mimura et al., 2007)

Projections

The IPCC suggests the climate in the Pacific could be in a permanent El Niño state with global temperature increases.

A World Bank study of the potential impacts of climate change scenarios in the Pacific (World Bank, 2000) projects the following by 2100:

• Sea level may rise 0.5m (“best-guess” scenario) to 1m (“worst-guess” scenario).
• Air temperature could increase between 1.6° and 3.4°C.
• Rainfall could increase or decrease (most models predict an increase) by 20 per cent, leading to more intense floods or droughts.
• Cyclones may become more intense, with wind speeds increasing by as much as 20 per cent; intensity could increase by 5 to 10 per cent by 2050 (Walsh, 2004 cited in Mimura et al., 2007).

Implications and possible future impacts

Changes in rainfall will also affect agricultural production. Loss of coastal land would reduce the available space for cultivation in some countries. In low-lying ones, salt-water intrusion would also affect production of copra, breadfruit and panadanus. A decline in the cultivation of some traditional crops, such as yams and taro, would also affect the subsistence economy of the Pacific islands (World Bank, 2000). 

The tuna fisheries in the western and central Pacific could collapse.

Diarrhoeal and vector borne diseases are expected to increase with warmer temperatures in the Pacific. As in the Caribbean, the frequency, severity and distribution of dengue fever could increase, as warmer temperatures reduce the incubation period of the dengue virus and speed up the larval stage of the mosquitoes.

Climate change could also increase the incidence of ciguatera poisoning. Habitat disturbance, including from extreme weather, and warmer waters cause the algal blooms that produce the ciguatoxins, which are ingested by fish. In Kiribati, which has one of the highest rates of ciguatera poisoning,  for example, by 2050 the incidence of poising is expected to go up from 35 to 70 people to 160 to 430 per thousand (World Bank, 2000).

Variations in rainfall will affect water supplies in some Pacific islands. Ground water supplies in low-lying islands could be affected by salt-water intrusion.

Coral reefs are also likely to be affected by bleaching events, which could lead to death of the corals and a decline in fisheries and a long-term reduction in coastal protection. Mangroves are likely to be affected by sea level rise and flooding and inundation will affect the costal zone in some islands.