Climate change scientists say rising seas will flood three times more people than previously thought

Around 300 million people will be vulnerable to annual flooding by 2050, three times as many as previously thought, according to a new climate change study.

Researchers concluded that previous ground elevation data vastly underestimated the extent to which coastal zones will be subject to flooding during high tide or major storms.

Data gathered by Nasa from a space shuttle mission has been widely used in previous predictions.

But the latest study used more accurate information from laser-based systems on aircraft.

Ben Strauss, chief scientist of Climate Central, a US-based research group, said: "Sea-level projections have not changed. But when we use our new elevation data, we find far more people living in vulnerable areas than we previously understood."

Part of the problem with the Nasa system was that it mistook rooftops and trees for ground level, he said.

Mr Strauss added: "It turns out that for most of the global coast we didn't know the height of the ground beneath our feet."

The new data showed 110 million people are already living below the current high tide line, rather than the 28 million estimated previously.

Under a model in which carbon emissions are not controlled the number of people subjected to flooding could rise to 630 million by the year 2100, according to the study.

More than two-thirds of the populations at risk in the coming decades are in China, Bangladesh, India, Vietnam, Indonesia and Thailand.

In each of several dozen major cities including Bangkok, Hong Kong, Shanghai, Mumbai, and Osaka, millions will find themselves in flood zones, the researchers said.

Scott Kulp, a Climate Central scientist, said: "Climate change has the potential to reshape cities, economies, coastlines and entire global regions within our lifetime.

"Nations will increasingly confront questions about whether, how much, and how long coastal defences can protect them."