Rising sea levels are already forcing one American town to relocate, with warnings that many others will follow.

The US Government announced this year it would pay $US48 million ($AU63 million) to help residents of Isle de Jean Charles in Louisiana to move as coastal erosion threatens to sink the community, reported news.com.

Residents of the town have been called the first climate refugees in the US and live in a town that can only be accessed using one road surrounded by marshlands along the Gulf of Mexico.

Since 1955, the Isle de Jean Charles has lost more than 90 per cent of its land due to saltwater intrusion and subsidence. Fruit trees have died off because of saltwater leaching into the soil and many properties bear the scars of flooding over the years.

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"Now there's just a little strip of land left," Rita Falgout, 81, tells Quartz. "That's all we have. There's water all around us."

Residents will have until 2022 to spend the government funding and relocate, something that will be a painful experience as many belong to the Biloxi-Chitimacha-Choctaw and United Houma Nation tribes.

"We're going to lose all our heritage, all our culture," Chief Albert Naquin of the Biloxi-Chitimacha-Choctaw told the The New York Times. "It's all going to be history."

But rising waters, regular floods and hurricanes have brought home the need for people to move. Residents are also lucky to have access to the $63 million program - which will only move about 60 people - as other bigger communities have not been so fortunate.

In January, the US Department of Housing and Urban Development agreed to fund the relocation of Isle de Jean Charles as part of $1 billion ($AU1.3 billion) in grants to help communities adapt to climate change.

But another town of 350 people in Alaska, Newtok, which is also at risk of sea level rise, had its funding application knocked back.

Its residents will now have to figure out how to pay for their own relocation to Mertarvik, a piece of land about 16 kilometres south.

It's no easy task considering a single energy efficient home in rural Alaska reportedly costs about $US300,000 (almost $AU400,000).

It's a problem that many more in the US and across the world will need to grapple with in the coming decades.

If sea levels rise by a worst-case scenario of 1.8 metres by 2100, this could see 13.1 million Americans lose their homes, according to a 2016 study.

Real estate provider Zillow has estimated this would mean nearly 12.6 per cent of properties in Florida would be underwater.

"We're already in for a sea-level rise that will put all low-lying coastal areas out of business, and that's using US government projections," Harold Wanless, chairman of the University of Miami's Department of Geological Science told AP.

"At some point in the not-too-distant future, we'll be leaving Miami ... we're all moving somewhere."

Even US President Donald Trump's own Mar-a-Lago mansion and private club in Miami could be threatened by rising seas, according to projections from the National Oceanic and Atmospheric Administration and the South Florida Regional Climate Change Compact.

South Florida roadways already flood routinely during storms or unusually high "king
tides," forcing cities to raise or move them and install expensive pumping systems.

New Orleans Mayor Mitch Landrieu has called climate change a grave threat to coastal communities, the nation and the world. He said that if unchecked, sea-level rise caused by climate change could mean that New Orleans and other coastal cities "will cease to exist."

And it's clear the government won't have the money to move everyone.

The $1 billion US government grant will also be spent on building stronger levees, dams and drainage systems across 13 states to address climate change but South Miami Mayor Philip Stoddard believes ongoing funding will be limited.

"The idea that the feds are going to buy people out has already failed. It's not happening nearly at the rate that it needs to happen," Stoddard tells Quartz.

"There's just nowhere near enough money. Maybe a few lucky people will get help, but it's going to be a shrinking minority."