Climate change risk far higher than previously thought; Sea-level rise could affect 13m US people

The number of people who could be displaced this century in US coastal regions — due to rising sea levels, as a result of climate change — is much higher than previously thought.

Thirteen million Americans are at risk of a 1.8m rise, including six million in Florida, scientists said.

The researchers, from the US Oceanic and Atmospheric Administration, assessed sea-level change scenarios that might have occurred by 2100 for coastal states, along with population growth trends and projections in high-risk areas.

With a sea-level rise of 91cm feet, locations forecast to house 4.2m people would be at risk of inundation, while a doubling of the rise would bring the number to 13.1m.

With its densely populated coastal locales, Florida faces the greatest risk, with up to 6.06m residents projected to be affected if sea levels rose 1.8m, followed by Louisiana (1.29m people at risk) and California (1m).

The figures in other states are: 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).

“As the sea level rises, coastal parts of Florida will be inundated,” said University of Georgia geography professor, Deepak Mishra, one of the researchers.

“Sea-level rise is the phenomenon that makes climate change a reality for millions of people worldwide. The sheer volume of people at risk of displacement, and becoming climate refugees, is the main threat.”

The projections are up to three times higher than previous estimates, said University of Georgia demographer, Mathew Hauer, the study’s lead author.

“These results suggest that the absence of protective measures could lead to US population movements of a magnitude similar to the 20th century great migration of southern African-Americans”, the researchers wrote in the journal, Nature Climate Change.

They were referring to the movement of six million black people from the rural south, during an era of institutionalised racism, to cities of the North, Midwest, and West, from the 1910s until 1970.