More than 13 million Americans, including six million in Florida, could be displaced by rising sea levels this century, three times what has previously been estimated.
The researchers assessed sea level change scenarios by 2100 from the US Oceanic and Atmospheric Administration for coastal states along with population growth trends and projections in high-risk areas.
With a sea level rise of 91 centimetres, locations forecast to house 4.2 million people would be at risk of inundation while a doubling of the rise would bring the number to 13.1 million.
With densely populated coastal locales, Florida faces the greatest risk, with up to 6.06 million residents projected to be affected if sea levels rise 1.8 metres, followed by Louisiana, where 1.29 million people are at risk, and California, with one million exposed.
Other states that could be heavily impacted in such a scenario include: New York (901,000 at risk), New Jersey (827,000), Virginia (476,000), Massachusetts (428,000), Texas (405,000), South Carolina (374,000) and North Carolina (298,000).
"Sea level rise is the phenomenon that makes climate change a reality for millions of people worldwide," said University of Georgia geography professor Deepak Mishra, one of the researchers.
The projections of the number of people who could be displaced are up to three times larger than previous estimates, said University of Georgia demographer Mathew Hauer, the study's lead author.
The researchers, writing in the journal Nature Climate Change, said the the rising sea levels could see movements in the US population similar to the 20th century Great Migration of southern African-Americans.
That shift saw more than six million black people migrate from the rural, racist South to cities of the North, Midwest and West from the 1910s until 1970.
The researchers said more than a quarter of residents of major urban centres such as Miami and New Orleans could face coastal flooding.
