Pacific islands ‘growing not sinking’, as sea levels rise


Pacific islands previously thought to be on the verge of disappearing under the waves because of climate change are actually getting larger, according to scientists.Kiribati, Tuvalu and the Federated States of Micronesia are among the countries whose islands have grown, according to the study, which appears in Global and Planetary Change.

Paul Kench at the University of Auckland in New Zealand and Arthur Webb at the South Pacific Applied Geoscience Commission in Fiji conducted their study using historical aerial photography and satellite images of 27 coral atoll islands in the central Pacific to observe changes over the last 19 to 61 years. During that time, sea levels have actually risen by 2mm per year.

They found that 23 of the islands either maintained the same land area or increased in size, while only four suffered a net loss to the sea. Kench told the New Scientist: "It has been thought that as the sea level goes up, islands will sit there and drown. But they won't. The sea level will go up and the island will start responding."

Why are the islands growing – and where does the extra material come from? Coral atoll islands are surrounded by coral reefs, which themselves continually grow, because they are formed by sea creatures. Reefs are eroded by waves crashing against them; the resulting coral debris is washed up on the islands – a process often helped by the presence of manmade structures such as causeways between islands.

And one effect of rising global temperatures – an increase in the frequency of hurricanes – could actually go some way to helping low-lying islands. When Tuvalu was hit by Hurricane Bebe in 1972, for instance, 140 hectares of debris washed up on a reef – and increased the area of the main island by 10 per cent.

Low-lying Pacific nations have been particularly vocal in advancing the cause of climate change mitigation. The Federated States of Micronesia recently appealed to Czech law to try to prevent a coal-fired power station being built in the European country.

And Tuvalu briefly held up talks at the Copenhagen UN climate change conference in December when it demanded a commitment to limit global temperature rises to 1.5°C above pre-industrial levels, saying: "Tuvalu is one of the most vulnerable countries in the world to climate change, and our future rests on the outcome of this meeting."

But nobody is declaring the emergency is over just yet. The 27 islands studied are a drop in the ocean when compared to the 30,000 dotted around the Pacific.

Kench told AFP there needs to be a sensible debate about the effects of climate change, rather than just assuming all the islands will disappear under the ocean. For example, inundation of these islands by sea water is still a major threat. As Kench says: "If islands still exist, will they still be able to carry human communities?"