Sad reason emperor penguin chicks are jumping off a 50-foot cliff in record-breaking footage

Footage of hundreds of emperor penguins diving at the edge of a cliff in Antarctica has a heartbreaking backstory behind it.

The shocking footage features in an upcoming National Geographic documentary Secrets of the Penguins, which is set to be released on Earth Day 2025.

Gathered beside a 50-foot cliff, the birds peer over the edge and consider whether they should jump.

Eventually, one takes the leap of faith - quite literally.

The others watch on, some craning their necks, as the bird splashes into the icy water below.

Once it surfaces, the brave penguin swims off to fill its stomach with fish, prompting the others to follow suit.

Usually, these birds would nest on free-floating sea ice.

There's a sad reason why. (National Geographic/Disney+)

But due to increasingly earlier seasonal warming caused by climate change, they have no choice but to nest on the cliffs.

According to the International Union for Conservation of Nature, the emperor penguin is considered as near threatened, with a population of 500,000.

Gerald Kooyman, who wrote a book about emperor penguins, claimed to have only seen the spectacle on video occur once before - thirty years ago.

He said: "Drifting snow had formed a gently sloping ramp from the sea ice onto a grounded iceberg, and a flock of departing chicks had marched up the ramp onto the berg.

"They were stopped by a 20-meter [roughly 67-foot] cliff over a sea that was sometimes open water and other times crowded with ice floes.” Over the course of a couple days, almost 2,000 chicks assembled at the ledge.

"Finally, they started walking off the cliff."

The doc airs on Earth Day next year. (National Geographic/Disney+)

Even scientists who monitor penguins from space with satellites say this is rare.

Although experts aren't saying cliff diving is caused outright by climate change, some are drawing links.

If emperor penguins continue to breed on cliff faces, this type of behaviour will become more common, according to Peter Fretwell, an Antarctic Survey scientist.

Climate change does pose a threat to the survival of the species however.

Fretwell said: "We estimate that we could lose the whole population by the end of the century.

"It’s heartbreaking to think that the whole species may be gone if climate change continues on the path that it’s on at the moment."

Some scientists remain optimistic that the penguins' hardiness - as demonstrated by their cliff dives - will see them adapt to survive.