At least 170 local communities in the United States could face chronic flooding because of a rise in sea level over the next 20 years, a report by the Union of Concerned Scientists warned. The number could rise to 670 by the end of the century, forcing the communities to move away.

Presently, more than 90 coastal communities in the US are affected by chronic floods caused by a rise in sea level, which in turn is the result of global warming.

By the end of the century, such deluges will occur from the eartern US state of Maine to Texas and along parts of the West Coast. Communities in Cambridge, Massachusetts, Oakland in California, Miami and St Petersburg in Florida, as well as in four boroughs of New York City may be affected.

The report is based on a study that mapped the rate of sea-level rise for hundreds of coastal communities for the first time.