In online footage, a man known only as Edward has in his hands on a picture he claimed shows Los Angeles submerged underwater in the future.
The earth’s atmosphere is warming, which is in turn creating climate change.
With the warmer climes causing ice caps in the north and south poles to melt, sea levels are gradually rising.
Environmental campaigners fear that, without limits on fossil fuels and pollution, there could be mass flooding in the world’s largest cities.
The self-professed time-traveller Edward says he is from the future and has first-hand knowledge that this isn’t just a warning but a reality waiting to happen.
Reading like something out of a sci-fi film, Edward bizarrely claims he is a time traveller from the year 5,000.
He told Apex TV, a YouTube channel focusing on paranormal stories, he was part of a top-secret time-travelling experiment in 2004 and was sent 3,000 years into the future.
The man claims he was shocked when he arrived in the future.
He realised he had landed in LA — the home of Hollywood in California, US — but it was submerged by a great body of water.
The Daily Star reported that Edward said he had been working in LA in a laboratory, when he said he was given the assignment to go into the future and take photographs.
In the video, the man's face is blurred and his voice distorted as he tells the story, supposedly to protect his identity.
He said: "I will tell you a story that will amaze you and you will be astonished.
"I appeared at a 'place'. It was unbelievable.
"I was standing on a huge wooden platform. Not only me, houses, buildings, of course, all made from wood. And after, I realised it was the same city, Los Angeles, but underwater."
In further astonishing claims, Edward also reckoned that he had spoken with people who lived in the real-life Atlantis, an ancient legend about a city situated underwater.
The residents told him the flood had happened due to global warming.
Time travel has yet, despite the conspiracy theories, to be a proven feat.
There have been plenty of people to have claimed to be time-travellers or rumours about where missing people have been, but nothing has ever been verified.
According to NASA, the sort of time travel alleged by Edward "only happens in books and movies".
The US space exploration organisation said: "Although humans can't hop into a time machine and go back in time, we do know that clocks on aeroplanes and satellites travel at a different speed than those on Earth.
"We can't use a time machine to travel hundreds of years into the past or future.
"That kind of time travel only happens in books and movies.
"But the maths of time travel does affect the things we use every day, for example, GPS satellites."
