It would cost billions to replace buildings like houses, schools, airports and power stations, which are currently at risk in the South Pacific from rising seas and other climate-change related events, say researchers.
The article, published today in the journal Nature Climate Change has analysed the vulnerability of 12 Pacific island countries to such hazards.
"In this research we undertake a comprehensive analysis of the exposure of built infrastructure assets to climate risk for 12 Pacific island countries," write Associate Professor Lalit Kumar and Dr Subhashni Taylor of the University of New England's School of Environmental & Rural Science.
"We show that 57 per cent of the assessed built infrastructure for the 12 Pacific island countries is located within 500 metres of their coastlines, amounting to a total replacement value of US$21.9 billion."
Islands in the South Pacific are generally small, low lying, and in an area of high tropical cyclone activity, which makes them very vulnerable to natural coastal hazards like tsunamis and climate change-related hazards, say the researchers.
Since most of the population, urban centres and critical infrastructure are located on the coast, Kumar and Taylor set out to study just how exposed the island nations were to sea level rise, coastal erosion, cyclones and storm surge.
The researchers analysed satellite data and information in a database of infrastructure, which included GPS co-ordinates for buildings, and their replacement cost.
Countries studied were the Cook Islands, Federated States of Micronesia, Kiribati, Marshall Islands, Nauru, Niue, Palau, Samoa, Solomon Islands, Tonga, Tuvalu, and Vanuatu.
The researchers looked at infrastructure including residential, commercial, public and industrial buildings, as well as airports, communications infrastructure, power generation, docks and ports, bridges, storage facilities, and water storage tanks.
Kumar and Taylor classified the distance of the infrastructure from the coast in four bands - 0-50 metres, 50-100 metres, 100-200 metres, and 200-500 metres.
"If most of your assets are, for example, within 100 metres of the coastline, then even small changes in sea level rise and associated extreme events present a high risk," says Kumar, a spatial modeller.
He and Taylor found eight of the 12 Pacific island countries have 50 per cent or more of their built infrastructure located within 500 metres of their coastlines, but some countries were more vulnerable than others.
"Our results show that Kiribati, Marshall Islands and Tuvalu have over 95 per cent of their built infrastructure within 500 metres of the coastline," says Kumar.
The study found that in Kiribati, 67 per cent of buildings fall within 100 metres of the coast.
Kumar says there is a lack of accurate elevation data in the Pacific, so the study did not include this.
But, he says, a large proportion of Pacific island countries are coral atolls or sandy islands, which reach a maximum of 3 metres in height. This means even buildings within 500 metres of the coast are quite vulnerable to climate-related hazards.
The findings from the study, funded by AusAID, will help aid agencies priorities their funding for climate change adaptation strategies, says Kumar.
- Australian Broadcasting Corporation
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