Explorer John Talbot, 72, has travelled thousands of miles to see endangered species around the world.

Since a liver transplant gave him a new lease of life six years ago, he has seen gorillas in Rwanda, elephants and eagles in Kenya and giant tortoises in the Galapagos Islands.

And now John, of Grangetown, Sunderland, has returned from five days in Canada, where he came face to face with polar bears.

"It was a fantastic experience," he said. "It took the best part of a day for me to travel there from Sunderland, but it was worth it.

"All of the bears would congregate within a five-mile radius of Hudson Bay, waiting for it to freeze so they could go hunting.

"It is absolutely desolate up there, but the bears are amazing to see in the wild. They would come right up to the vehicle we were in and reach up. You only get a true idea of how big they are when you see them up close as they stretch out. They are absolutely huge."

Ecology experts believe the polar bear could be made extinct by global warming within 100 years.

The animal, which relies on sea ice to catch seals, is already starting to suffer the effects of climate changes.

Populations are dependent on having sea ice and those most at risk of dying out are at Hudson Bay, Canada, say scientists.

Arctic sea ice is said to be melting at a rate of up to nine per cent per decade. Arctic summers could be ice-free by mid-century.

"They've actually seen a rise in the number of tourists up there because it is feared that the bears won't be around for too much longer," said John.

"People want to see them before they are gone for good. You even hear stories about some of the bears resorting to eating each other because they find it so hard to go hunting. It's a terrible situation."

John has also seen the sights of Egypt, Tunisia, Australia, the Caribbean, Ecuador, South Africa, Russia and Antarctica. His next stop is Indonesia.

"I'm 72 now, but I have no plans to give up travelling yet," he said. "The operation has given me a new lease of life and I'm going to make the most of it."