Media playback is unsupported on your device Media caption The first flight over Mount Everest captured by Major Stewart Blacker in 1933

The Royal Geographical Society is releasing the films of the scientific explorations it sponsored in the early 20th Century.

The priceless footage, some of which has not been seen for nearly 100 years, is being digitised and put online.

The films are also helping scientists today learn more about the impact of climate change.

BBC News has had exclusive access to the films.

Among them is the first aerial footage of the top of Mount Everest. It was shot in 1933 by Major Latham Valentine Stewart Blacker, a former fighter pilot and war hero. He was a real life Biggles!

Blacker and his friends risked their lives flying in specially built biplanes, higher than anyone had flown before, to capture historic footage. Alasdair MacLeod, who is in charge of the project for the RGS, says that the film is one of more than a hundred in the RGS's possession that will be put online this year.

"The society has a collection of over two million items. It's the world's largest collection of geographically related maps, photographs, artefacts, diaries, notebooks and publications. And this film collection, which has been housed at the British Film Institute's national archive for many years, has not been made more accessible."

Media playback is unsupported on your device Media caption Dancers in Tibet in 1922 wearing an apron made from human bones

But it has now. The most shocking is the earliest known footage of Tibet shot in 1922.

It was taken by an army officer, Captain John Noel, on the first ever attempt to reach the top of Mount Everest.

He filmed a scene at a monastery on the way to Everest where the climbers seek a blessing from the monks. They are treated as honoured guests and shown ritual dances, telling stories of reincarnation.

Around the dancers' waists are aprons made from a lattice of human bones; their face masks are made from stretched human skin.

Captain Noel's daughter Sandra told me that the attempt to climb Everest was like the Moon landings at that time.

"This was going to be a world event and it captured the imagination. People had just emerged from the war. They were impoverished and had very little to be excited about. And here was this expedition to Mount Everest."

Captain Noel's footage is of scientific as well as historical value. It will be used by researchers to compare with current images to help them assess the impact climate change has had on the Himalayas over the past 100 years.

Media playback is unsupported on your device Media caption Ralph Bagnold and his friends drove thousands of miles into the Libyan Desert

In 1932, cinema audiences were amazed to see the exploits of another young army officer, Ralph Bagnold, journeying thousands of miles across the Libyan Desert in a car.

When one of the cars broke down it was cannibalised for spare parts and abandoned. And they are still out there somewhere buried among the dunes.

The vehicles would often get stuck in the sand - and each time Bagnold and his team would find ever more ingenious ways of extricating them.

It seems like an odd thing to do now, but Bagnold and his friends risked their lives on this expedition because they saw it as a great challenge - so says the adventurer's son, Stephen.

"The experts proclaimed it couldn't be done. To dad that was the greatest possible spur, not that he wanted to show that he was the master or anything like that, but just because it tickled his fancy and that maybe with clear planning and with the right equipment there could be a way of crossing the desert," Stephen told BBC News.

Bagnold took careful measurements during his expedition to understand how the sand is moved by the wind. He published several research papers on the subject.

His work would later help the American and European space agencies explore Mars. His insights are being used to design rovers that can cross Martian sand without getting stuck.

Media playback is unsupported on your device Media caption Skyscrapers were built from mud in 16th Century Yemen

Thousands of miles away in Yemen a pilot, Aubery Rickards, filmed the Hadhramaut, a region that is home to an ancient civilization.

The film shows startling scenes of a dense collection of skyscrapers made from mud that were built in the 16th Century.

Some are 11 stories high. They are still inhabited to this day.

It was in this area that people first learned how to live in concentrated environments. It is sometimes referred to as "the Manhattan of the desert".

Perhaps the most inspirational films are those shot by two young explorers, George Sherriff and Frank Ludlow, in the 1930s during their journeys through Bhutan and Tibet.

The two friends thought they had discovered paradise among the Himalayan mountains. They filmed scenes of a simpler way of life, where people were happy, healthy and lived to a ripe old age.

Media playback is unsupported on your device Media caption George Sherriff and Frank Ludlow film their "Shangri-La"

The early colour films reinforce a sense they had found a brighter, more hopeful world - a contrast to the grim desolation of Europe after the First World War, according to Prof Mike Heffernan, of Nottingham University.

"When Sherriff and Ludlow began their exploration of this area in 1933, it is exactly the same year in which James Hilton publishes this famous book called The Lost Horizon, which introduces the idea of 'Shangri-La'; this perfect place. This was a mountain kingdom, a vestigial world of peace and harmony, precisely the world that had been so obviously left behind by the industrial warfare that they'd gone through."

You can watch Pallab's documentary "Great Explorations" on BBC World News (all times GMT) on Saturday at 01:30 and 08:30; on Sunday at 14:30 and 20:30; and on Monday at 02:30 (North & Latin America only).

The documentary will also be broadcast in the UK on the BBC News Channel (all times BST) on Saturday at 16.30, and again on Monday at 00:30, 14:30 and 20:30.

The Royal Geographical Society films featured can be viewed in full for free online via the BFI Player

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