In the present era of global climate change, steady rise in sea levels and storm surges have become frequent phenomenon, something that has been threatening massive population living in the coastal regions. A team of demographers has forecast that millions of Americans living along the nation’s coasts will be forced to move inland by the end of the century as the climate change worsens.

A study published Monday in the journal Nature Climate Change says that America’s coastal areas, where around 13.1 million people live, could be prone to flooding by 2100. In Bay Area alone, 250,000 people in low-lying parts of San Mateo County would be affected while some 33,000 would be forced to move to San Francisco.

The sea level could possibly increase by three feet or even more over the next century if emissions continue to persist at the present level, thus threatening most shoreline communities. Demographers also argue that since forecasts do not account for growth in population, most projections could be underestimating the number of people who would be at risk.

The study authors used data from the National Oceanic and Atmospheric Administration to show that millions are at risk. A high-end estimate showed that 4.2 million people would be at risk if seas rise by three feet while a six-foot rise would threaten 13.1 million.

Benjamin H. Strauss, an expert on sea-level rise at Climate Central, a climate change research organization, said, “The continuation of current development patterns through the rest of the century seems like an unlikely future because as sea levels continue to rise and coastal problems become glaringly obvious, coastal development and real estate will have to change”.

Strauss, however, said he is of the opinion that the new study has overstated the number of people at risk, though he agreed that most estimates are too conservative.