Marseille faces major flood risk

CLIMATE change and rising sea levels could mean the world’s leading coastal cities – with Marseille being the financial and business centre most at risk in France – facing increased flooding with costs running into the billions to provide basic protection.

A study for the Organisation for Economic Co-operation and Development (OECD) said that the 136 leading coastal cities could face losses of a trillion dollars a year - €750billion a year – as they had been designed to cope with past sea levels.

They were built to cope with expected 100-year storm surges but were not built to face the expected 0.4metre rise caused by climate change over the next 40 years and the more devastating floods that will be produced.

World Bank economist Stephane Hallegatte led the study, called “Future Flood Losses in Major Coastal Cities” and published in Nature Climate Change, and said: “Inaction is not an option. Coastal cities will have to improve their flood management, including better defences, at a cost estimated around €37.5 billion per year for the 136 cities.”

The cities expected to face the most financial risk from flood damage are Guangzhou (formerly Canton in China), Miami, New York, New Orleans and Mumbai.

However, the study pointed out that the Mediterranean, despite being an almost closed sea, could not escape the global rise in sea levels – which would mean cities like Marseille, Athens, Beirut and Naples being at risk. Other towns and cities along the French coastline would also be at serious risk, but the financial costs would be less than for Marseille.

Mr Hallegatte said: “Coastal defences reduce the risk of floods today, but they also attract population and assets in protected areas and thus put them at risk if the defence fails, or if an event overwhelms it. If they are not upgraded regularly and proactively as risk increases with climate change and subsidence, defences can magnify – not reduce – the vulnerability of some cities.”
Photo: Ville de Marseille