They are fighting to preserve their ancient lifestyles and the very ground under their feet as the Arctic ice cap shrinks and the tundra's permafrost slowly turns to mush.

Polar circle film-makers at this year's Berlin Film Festival are taking a cold, hard look at the plight of the indigenous people on the frontlines of climate change.

In a top-down view of the planet, the NATIVe showcase features films from the icy northern latitudes of Scandinavia, Siberia, Alaska, Canada, Iceland and Greenland.

The common theme is the twin threat faced by native peoples who have traditionally herded reindeer or caribou, or hunted seals and whales, before nation-states put them into permanent towns and their children into residential schools.

In the historical documentary "Kaisa's Enchanted Forest," director Katja Gauriloff tells the story of her late great-grandmother Kaisa, a weathered matriarch of Finland's Skolt Sami minority.

Using old black-and-white footage, it portrays the simple life of the semi-nomadic Sami in summer lakeside cabins and winter block huts, their children riding reindeer and skating on frozen lakes.

Kaisa shares her folk wisdom and magical tales -- she uses white bird feathers to sweep her hut because, she says, evil spirits mistake them for an angel's wing.

The tale darkens when World War II destroys the Sami's ancestral homes and forces them into camps where disease takes a heavy toll. They later move to a permanent settlement, their lives from now shaped by assimilation into Finland.

Gauriloff said that today her community counts just a few hundred people, adding that "the reason I don't speak my mother tongue is there on the screen".

- Tundra teddy bears -

Another loving depiction of a vanishing way of life close to nature is "The Tundra Book. A Tale of Vukvukai -- The Little Rock".

It is an intimate portrait of the 78-year-old Vukvukai and his clan in Siberia's Chukchi community, which lives far north of the tree line.

Viewers are invited into his clan's heavy-skinned yurts as icy winds howl outside, and watch as herders corral, lasso and wrestle down reindeer for slaughter, offering their thanks to the creator.

The audience laughs as children in furry overalls tumble through the snow, resembling teddy bears.

Then, in the chapter "Steel Bird Takes the Kids Away", a helicopter carries the children off to a Russian state residential school where they spend 10 months of the year.

"Women give birth to people just to throw them away," says a distraught Vukvukai, knowing his language and way of life are disappearing.

"How will we survive?"

Director Aleksei Vakhrushev said that one of Vukvukai's sons went on to work as a gold miner, got drunk one day, lit a cigarette near a petrol canister and died in the explosion.

- Mammoth bones -

The other common threat for the polar circle communities is melting sea ice and the thawing of the permafrost that covers a quarter of the northern hemisphere.

Scientists say this will release huge amounts of carbon into the atmosphere, in turn accelerating global warming.

But for local indigenous people, warming is already an existential threat, said Vyacheslav Shadrin, chief of the Council of Yukaghir Elders in Siberia's Yakutia region.

"A change of two or three degrees may not seem so big when it's minus 40," he said at a panel talk during the Berlinale festival.

"But a really big problem is weather instability. Hunting, fishing, reindeer herding all depend on our ability to predict the weather and animal behaviour," he continued.

"Now our elders say nature doesn't trust us anymore."

He said that last winter, unseasonably early snowfalls blanketed lakes before the ice was thick enough to support vehicles -- leaving remote villages cut off for months, short of food and fuel supplies.

Riverside villages now face "catastrophic floods" and heavy erosion almost every year as a result of warmer, wetter weather and increased snow melt.

"Last year it didn't happen," Shadrin said. "That was like a gift from the gods."

On the ocean front, once covered by sea ice, waves now crash into an already destabilised coastline, Torsten Sachs of the German Research Centre for Geosciences said at the same event.

Sachs, who works in Siberia, Alaska and Canada, said the thaw was also causing the sudden draining of tundra lakes, or the appearance of new ones "where they aren't wanted".

Shadrin said the thaw had another effect -- making the collecting of ancient mammoth bones "big business", even though this breaks an age-old taboo.

Some tribal elders think this is what has caused the climate disaster, Shadrin said.

"In our world view the mammoth is the god of the underworld," he said. "If you take the bones, you open the door to the evil spirits from the underworld."