As France prepares to mark 80 years since Allied forces landed on the beaches of Normandy, the historic coastline faces a new threat -- rising sea levels linked to climate change. More than 100 kilometers (62 miles) of Normandy's coastline bear traces of June 6, 1944, including bunkers, shipwrecked vessels, and other vestiges from the Allied troops' first step to freeing western Europe from Nazi German occupation. But now, the sea from which 150,000 Allied troops conducted the largest seaborne invasion in history threatens those same heritage sites.

Rising sea levels are eroding dunes and cliffs, while marshes and reclaimed land risk submersion at sites visited by millions each year. The famed beaches –- code-named Utah, Omaha, Juno, Sword and Gold –- that were stormed by US, British Commonwealth and other allied troops have all drastically changed in 80 years. The D-Day sites "already bear no resemblance to what Allied soldiers experienced on June 6, 1944", said Regis Leymarie, a geographer with the Coastal Conservatory in Normandy.

"We're in the process of moving from historic sites to places for interpreting history," he added. And changes are coming fast. Rising global sea temperatures are accelerating the melting of polar ice caps and increasing sea levels, posing a threat to Normandy's coastal communities.

"The environment will be transformed in 10 years or so," said Leymarie. – 'We don't have any help'- For some communities, these changes are already here. In Gra.