Threat to life on Arctic frontline
As the days lengthen with the approach of spring, the northernmost reaches of Scandinavia are about to witness the annual migration of huge herds of reindeer.
After spending the winter inland in Finnmark, Europe's last great wilderness, the animals are moved to pastures near the coast for the summer.
The reindeer play a central role in the livelihoods and culture of the indigenous people of the region, the Sami, but this way of life is under pressure, as I saw on a journey in northern Norway earlier this month.
Look at a map of the region and you'll see very few roads and only a handful of towns. Our expedition of nine people, each towed by a team of huskies, hardly encountered another soul.
Led by our guide, Tom Frode Johansen, we passed through valleys and over hills, along the border between Norway and Finland, and then across frozen lakes and uplands of unblemished white.
When it was cloudy - or when there were flurries of snow - the landscape appeared almost lunar and barren, and it was impossible to imagine any kind of animals enduring here.
But when the sun came out, a golden light would transform the scene, revealing the details of cliffs, streams, clumps of woodland and - most significantly - herds of reindeer.
Brown and sturdy, their antlers silhouetted against the white, the reindeer clear away the snow to reach the food they rely on in winter: lichen. It does not seem to amount to much but it does mean that life is possible here.
And one night we saw how central the reindeer are to the lives of the Sami people.
We had been on the move for 12 hours and shelter from the cold couldn't come soon enough.
It was well below freezing and the snow was so deep that we sank into it past our knees.
A tiny glimmer of light shone from the window of a hut ahead of us. This was to be our sanctuary.
Our torches picked out the wooden walls of the small building; otherwise we were in a landscape so empty it was hard to remember that Finnmark is part of the overcrowded continent of Europe. My mobile phone hadn't had a signal all day.
As soon as we walked in, our host, Ellen-Anna Siri, welcomed us with an enormous dish of stew - of reindeer meat, of course - and exactly what we needed.
For breakfast the next day she and her mother Kristine offered a plate of dried reindeer heart which was also delicious.
And the two of them couldn't resist dressing my daughter Kitty in the full traditional Sami woman's costume of reindeer leather and embroidered hat.
The connection between the Sami people and their reindeer has been about survival in a hostile land and it runs very deep: there is a legacy lasting millennia of living together in the polar North.
The most immediate threat, we were told, is from wolves, bears and wolverines.
Attracted by the reindeer herds, these predators are highly aggressive so Ellen-Anna warned us about going outside at night.
If you need to go to the toilet, she said, which involved walking quite a distance through the snow, make sure you're accompanied so someone can keep a lookout.
Suddenly, the wilderness seemed very wild indeed.
But for the Sami this is nothing compared to the fundamental challenges they have faced.
Historically, as semi-nomads, they have been irritating to the various governments here.
For years Norway tried to make the Sami people more Norwegian. And along with Finland, Sweden and Russia, Norway closed its borders at various times, blocking the annual migrations.
In the Second World War, when the Nazis were driven back by the Soviet Army, the Sami suffered terribly.
Then the nuclear accident at Chernobyl in 1986 released a radioactive cloud which contaminated thousands of reindeer.
More recently, with rising temperatures in the Arctic, the Sami say the shorter winters are forcing them to change the patterns of their herding.
Grazing lands threatened
On top of that, the grazing lands are under constant pressure from developers and prospectors who are lured by deposits of gold, copper and iron ore.
Reindeer herding is no longer the only possible activity in these snowy lands.
Inevitably, there has been a drift to the cities, to an easier life; traditional cultures experience that loss the world over. But the Sami are showing a powerful streak of resistance.
At our destination, Kautokeino, a town regarded as a Sami capital (with a parliament and university), we watched a kind of Sami Olympics.
People had travelled from across the region to be there and the games attracted a lively mix of accents and languages.
The highlight was the reindeer racing, the animals tugging youngsters on skis at incredible speed.
Later there was a full house for a competition for 'yoiking': yoiks are songs of praise, highly personal and often haunting. I found one sung to a daughter particularly moving.
But then a band struck up. Yoiks have had an electronic makeover that's given them the sound of something from the Eurovision song contest.
My first thought was that Sami culture could easily drown in a sea of light pop; but then I wondered if this was actually a clever way of keeping alive an age-old practice.
I stepped outside into the bitter cold. Above me a vast green stripe arced across the sky: it was the mesmerising sight of the Northern Lights, strangely shaped clouds glowing and twisting from horizon to horizon.
It occurred to me that the Sami people are among the very few to live under this spectacular show; and their ancestors must have enjoyed it too.
Somehow the Sami have adapted and coped and survived over thousands of years, each generation gazing up at the swirling luminous skies while warming their hands on a bowl of reindeer stew.
Learn more about the Sami people by listening to David Shukman's report from Scandinavia on From Our Own Correspondent.