Climate change warning: Three times more coastal homes may be lost than previously thought

Coastal properties could become uninhabitable within the next three decades, affecting hundreds of millions of people, a new study claims.

The global sea level has already risen almost 20 centimetres since the industrial age and further rises could have a devastating impact on many countries, with a new report suggesting three times as many coastal residents are more vulnerable than previously thought.

The report warns annual floods could affect areas that are home to 300 million people in just 30 years, if people fail to cut carbon emissions.

China, Bangladesh, India, Vietnam, Indonesia and Thailand are the countries most at risk.

Climate Central USA's Scott Kulp and Benjamin Strauss, who led the Springer Nature study published in Nature Communications, used computer modelling to assess global exposure to extreme coastal waters.

They say their model estimates show about 110 million people living on land below the current high tide line, and 250 million on land below current annual flood levels.

"This is in contrast to previous estimates 28 million and 65 million respectively."

According to the research, it's estimated one billion people occupy land less than 10m above high tide levels, with 250 million people living just less than one metre above high tide.

The research says most previous estimates of global average sea level rise in the next 100 years have been below 2m.

Under scenarios of higher emissions, a rise more than 2m may be possible in the 21st century, the research says.

"Translating sea-level projections into potential exposure of population is critical for coastal planning and for assessing the benefits of climate mitigation, as well as the costs of failure to act."