By Alex Kirby BBC News Online environment correspondent

The Arctic is a very important ecosystem to the health of the rest of the planet Rosemarie Kuptana

They say increasingly unpredictable weather is significantly altering the way they live.

They are having to get used to unfamiliar birds and fish arriving from further south.

Some believe the warming could be the start of a process that may prove unstoppable.

The Inuit live in Sachs Harbour, a tiny community on Banks Island, which lies north of Canada's North West Territory, lapped by the Beaufort Sea.

Coping with the unknown

They reveal their forebodings in Sila Alangotok - Voices From The Tundra, a film made by Television Trust for the Environment (TVE) in its Earth Report Series for BBC World.

 Click hereto watch BBC World's report on Sachs Harbour.

One resident, Rosemarie Kuptana, is on the board of the International Institute for Sustainable Development.

Musk oxen are replacing vanishing caribou

She tells TVE: "What's scary is that there's uncertainty because we don't know when to travel on the ice, and our food sources are getting further and further away.

"We can't read the weather like we used to. It's changing our way of life. We live in a very extreme and harsh climate now.

"We've always had extreme weather conditions, whether it's 24-hour sunlight, or whether we've got blizzards with no visibility in the winter. What is more extreme now is that there's no predictability."

The earlier springs and later autumns make it harder for the people of Sachs Harbour to predict when they can hunt and trap.

Ominous arrivals

There are novel species, as John Lucas explains: "Springtime comes around, and you start seeing different kinds of birds, barn owls, that sort of thing.

No way: Mud covers a beach

"We've never seen them up here before. We're getting different kinds of geese, ducks, mallard, pintails that we never used to see around here."

There are now salmon to be caught - another sign of warming weather, the Inuit believe.

But it is what is happening to the land itself that many of them find most disturbing.

Most of Banks Island is covered by permafrost, which is now melting. John Keogak tells TVE: "I'd say about '87 we started noticing these mudslides. Before, it used to be a little sloughing from the snow left on the side of the banks.

Slipping away

"But now it's the permafrost that's coming down, and the ground being disturbed, and more of the permafrost being exposed to the sun and the heat and the wind.

Arctic char: Salmon are moving in

"Now there's more rain and the sun is shining all the time... Once this starts I don't know what's going to stop it... I think the bigger it gets the faster it will go.

"It just started off small. Down here we used to be able to walk along the beach - now it's all mud."

Another resident recalls how, when he worked at the local airport, he reported a thunderstorm.

Warning the world

He was told: "You guys can't get thunderstorms. It's too cold." This year, in contrast with the recent trend, has turned out surprisingly cold.

Rosemarie Kuptana asks: "How can we prepare ourselves for such unpredictability? What will happen to us if we can no longer rely on our instincts and traditional wisdom?

"I believe the Arctic is a very important ecosystem to the health of the rest of the planet.

"I guess what we can do is just try and educate people and say: 'Hey, watch out, this is what's happening to us.'"