Small islands, including those in the South Pacific, are already experiencing the effects of climate change, according to the latest report from the Intergovernmental Panel on Climate Change (IPCC).

Key findings from the IPCC’s Working Group II chapter on small islands are being released today as part of a worldwide series of regional briefings on the IPCC report about climate change impacts, adaptation, and vulnerability.

Penehuro Lefale, of the New Zealand Meteorological Service (MetService), is one of the lead authors of the small islands chapter. He says the report identifies small islands, including those in the South Pacific, as one of four regions of the world likely to be especially affected by climate change. (The other three regions are: the Arctic, Africa, and Asian megadeltas).

Observed climate trends cited by the small islands chapter include:

• Annual and seasonal ocean surface and island air temperature have increased by 0.6 –1.0°C since 1910 throughout a large part of the region southwest of the South Pacific Convergence Zone
• Fewer hot days and warm nights, and significantly fewer cool days and cold nights, particularly in years after the onset of El Niño, 1961–2003.
• Analyses of satellite and tide gauge data show a maximum rate of sea level rise in the central and eastern Pacific, spreading north and south around the sub-tropical gyres of the Pacific Ocean near 90°E, mostly between 2 and 2.5 mm/year, peaking at over 3mm/year for the period 1950–2000.

Future climate change projections include:

• Increased seasonal surface air temperature ranging from 0.45 to 3.11°C, relative to the baseline period of 1961–1990, by 2100.
• Projected changes in rainfall range from –14.0 to +14.6% by 2100 for the Southern Pacific. More rainfall is projected during summer months, with likelihood of more frequent heavy rainfall events.
• Projected globally averaged sea level rise of 0.18 to 0.59 m by the end of the century, depending on model assumptions. Models indicate a geographical variation of sea level rise.
• The number of intense cyclones is likely to increase, though the total number of cyclones overall may decrease on a global scale.

"Overall, this assessment confirms and strengthens previous observations reported in earlier IPCC assessments that small islands are highly sensitive to climate change and sea level rise. It found adverse consequences of climate change and variability is already a reality for many inhabitants of small islands", says Pene Lefale.

"Climate change is likely to heavily impact coral reefs, fisheries and other marine-based resources of small islands of the Pacific," he says. "There is likely to be a decline in the total tuna stocks and a migration of these stocks westwards, both of which will lead to changes in the catch in different islands."

According to the report, "Sea-level rise is expected to exacerbate inundation, storm surge, erosion, and other coastal hazards, thus threatening vital infrastructure, settlements, and facilities that support the livelihood of island communities." For example, says Pene Lefale, "international airports on many small islands are mostly sited on or close to the coast, and the main – and often only – road network runs along the coast. Under sea-level rise scenarios, many of them are likely to be at serious risk."

The report says climate change is expected by mid-century to reduce water resources in many small islands, including those in the Pacific, "to the point where they become insufficient to meet demand during low rainfall periods."

"We’re also likely to see impacts on other sectors such as food security, human health, insurance, and tourism," says Lefale. "For example, if the intensity of tropical cyclones increases, a concomitant rise in significant damage to food crops and infrastructure is likely. Tropical Cyclone Ofa in 1990 turned Niue from a food-exporting country to one dependent on imports for the following two years, and Heta in 2004 had an even greater impact on agricultural production in Niue. In the health sector, many small islands currently suffer high health burdens from climate sensitive diseases, including morbidity and mortality from extreme weather events, certain vector borne diseases, food–and water–borne diseases. Increasing temperatures and decreasing water availability due to changes in extreme weather and El Niño Southern Oscillation events may increase burdens of climate sensitive diseases such as diarrhoeal and other infectious diseases in some small islands. With regard to tourism, deterioration in coastal conditions, such as through beach erosion or coral bleaching, is expected to reduce the value of these destinations for tourism."

"Adapting to climate change is a challenge for many small islands," he says. "Past studies of adaptation options for small islands have been largely focused on adjustments to sea level rise and storm surges associated with tropical cyclones, with emphasis on protecting land through hard shore protection measures rather than on other measures such as accommodating sea level rise or retreating from it. More recent studies have identified major areas of adaptation, including water resources and water shed management, reef conservation, agricultural and forest management, conservation of biodiversity, energy security, increased development of renewable energy, and optimised energy consumption."