Sometimes I go out alone in winter, with my dogs, and I'll stay on the ice for weeks at a time. It's tough and you have to be alert. But when you reach a certain level of physical ability, it's like you go to another plane. It's impossible to express, and probably makes no sense to you. In fact there's probably no point me even telling you."

The man questioning my powers of comprehension was Gary Rolfe, a British dog-musher who has been living in a hamlet on Scoresbysund in eastern Greenland since 2007.

"What did you do before this?" I asked. He shared only the scantiest details. "I've had bad times, made mistakes. I'm from the East End, E17, Walthamstow, and I'm 45 and a half."

He grinned, then added: "Out on the ice, when it's dark, I feel – I know – there are Inuit who have never met Westerners, who wear fur and skins, and live as they have always done. A lot of people here believe the same. They call them the 'little people'."

Right then I felt like a little person myself. I'm 45 and a half, too, live in south-west London and was not alone on the ice cap, but sharing a centrally heated cruise ship with 100 wealthy, mainly pension-age people. The combination of three gourmet meals a day and limited activity – mellow hikes, dinghy rides, trips to the sauna – was only going to lift one thing to another plane: my midriff.

I watched Gary feed seal blubber and meat to his lively pack of beautiful huskies, chatted a while longer and sloped off to the Zodiacs.

I had boarded the Akademik Sergey Vavilov in Reykjavik. This was my third voyage in subpolar seas, and on each cruise I had sailed, by fluke, on the same sturdy Russian ship. I didn't need a recce to find my cabin, the lifeboats or the restaurant, so I went straight on deck to watch Reykjavik retreat.

Greenland was, in my mind, an enigma. I couldn't say why I wanted to go there, but it had something to do with emptiness, the tabula rasa of a white, continent-sized island. Everything else about the cruise seemed peripheral. I wasn't sure what I expected or if, seeing it for real, the Arctic would come alive more than it does in heroic narratives and geography lessons.

To get us into the mindset for Nordic landscapes, the ship first sailed south and east to enter the narrow harbour of Heimaey in the Westman Islands. A mere volcanic hiccup off the south coast of Iceland, it is home to 4,500 people, clustered together as if in fear of the weather, or the magma. It was chucking it down but, conscious that this was a rare opportunity to stretch my legs, I disembarked. From the top of a hill I could see new parts of the island that had erupted out of the sea in 1973, and a road up to a volcanic memorial park, where homes had been buried under lumps of lava.

As night fell, we set off across the Denmark Strait. The swell grew and the wind howled for a full night and day, while I settled into life on board: I read, dined, made friends and adapted to the rhythms of the sea and 18 hours of daylight.

On the second day, a fog fell and the sea turned to grey glass. I attended a couple of lectures, but preferred to be on deck. While everyone else was in an airless, windowless room learning about geology, I spotted humpback whales and a pod of white-nosed dolphins. Minke and fin whales also broke the surface, but for the most part it was just the ship and a dozen feisty fulmars dancing on the wind.

With a noticeable dip in temperature and a clear sky, Greenland came into view with the dawn. We reached Gary's village, Ittoqqortoormiit (population 469), by turning right off Scoresbysund, the biggest fjord complex in the world. I had only ever glanced at Greenland on maps. The world's biggest island, it is also the least charted country; the interior is an incomprehensibly large patch of contour-free white, and the east coast has only a handful of settlements and a population of about 3,500.

I wandered Ittoqqortoormiit's gravel streets, climbed to a heliport overlooking an iceberg-strewn bay, visited the cemetery and the grocer's and chatted to locals. The schoolchildren had a day off because of our visit, and one young Inuit told me he was off to Denmark to become a helicopter pilot. Choppers are more common than cars in eastern Greenland and are, along with boats in summer and skidoos in winter, the only mode of transport between the airport at Constable Point and Ittoqqortoormiit.

The town was orderly, with wooden houses painted according to function (commerce: red; utilities: light blue; hospitals: yellow). It contained all the key civic buildings: church, post office and bank, old people's home, sports hall, a memorial to Jean-Baptiste Charcot's "Pourquoi-Pas" expedition of 1936, a guesthouse and a tourist office. There was a sense of purpose, with diggers digging, cargo being inspected, a fishing boat in the harbour and washing flapping in the icy wind – an FC Barcelona shirt, a pair of underpants, a polar bear skin.

No one on the Vavilov had been openly talking about it but the polar bear was the reason my ship was full of passengers. Yes, they'd tick off walruses, whales, seals and seabirds – kittiwakes, black-backed gulls, terns and Arctic skuas – but above all they wanted to ogle the top predator of the Arctic.

Sublimely beautiful, awe-inspiringly strong and very, very frightening (just before our trip a British schoolboy had been mauled to death by a polar bear in Svalbard), Ursus maritimus appeals to humans for the same reasons lions do. That it is such a hardy animal and yet desperately threatened injects a grim "last chance to see" element.

From Ittoqqortoormiit, the Vavilov sailed west, deep into Scoresbysund, and we explored – from the deck, in Zodiacs, on foot and in kayaks – places I had never heard of: Nordvestfjord, Kap Leslie (in the world's largest national park) and Danmarks Island, where I saw stone houses built by a long-gone indigenous group – probably Gary's "little people", said the guide.

Cruising around, you can get blasé about icebergs. Read about the endeavours of Franklin, Ross and Nansen, and all those who explored in the days of sail and low-tech clothes, and you cannot but feel admiration. The bergs that had floated down from the immense Daugaard-Jensen glacier were bigger than any I had seen in Antarctica and, when viewed from the coast, dwarfed the 120m-long, 6,500-ton ship. Some were smooth, peaceful and ringed by turquoise water; others invited anthropomorphic comparisons – I spotted a church organ, a dragon and a shiny, troll-sized phallus.

The tundra came to life through flora – Arctic blueberries and lemon-scented mountain sorrel, saxifrage that withstands absolute zero and horizontally growing willow "trees". Fauna was not abundant, but new sightings for me were feather-footed ptarmigan, bright-white Arctic hares and a dozen musk ox, a shaggy remnant of the last ice age.

It was great to be out and about, hiking in mossy bogs, scrambling over lava and granite to reach a summit and gawping at snowy 2,000m peaks, mile-wide glaciers, fjords bigger than cities.

For much of the time, the sun shone, which was lovely if unfitting, and I tried to soak up Greenland for its glories – and not think about polar bears.

Despite its ties with Denmark, Greenland is a flight from the things we are most familiar with. If it is, at 1,300 miles, not far from Britain in distance, it lies much further away in every other aspect. It is resistant to the tourist's quest. It has no cities, no native trees, no significant indigenous ruins. There's not much to buy; not even a headbanging local grog. The food is ordinary, at best: smoked musk ox, which an Inuit chap in Ittoqqortoormiit gave me to taste, was salty and tender; Narwhal skin, which the Vavilov's chef included in a lunchtime buffet, was egregiously inedible.

Greenland, in a way, is a set of negations covered in ice and, come winter, shrouded in darkness. But Gary said he loved winter most, and I knew from a visit to the National Maritime Museum's "High Arctic" exhibition that Inuits associated the long night with the freedom of dreams.

Gary said I should return at New Year and go dog-driving with him, though he added that the airport sometimes closes because of blizzards, so I might have to stay till Easter. "In winter, you travel by the light of the moon or by the Northern Lights and watch for polar bears stalking from downwind," he said.

As the Vavilov turned northeast for Svalbard, some people were complaining that they hadn't seen much wildlife. I think they were just struggling, as I was, to make sense of a cold desert, bereft of forest and settlements, and of the big, empty-seeming sea. The crossing was never rough, and the mild seasickness I suffered for half a day was due to a bout of rye whiskey in the bar – my one night on the tiles, with half the drinks taken outside, with auks chattering and a sei whale blowing. Sixty hours passed in a blur of books, meals and watching.

After one long morning on the bridge I went to a lecture entitled "Polar Bear: Icon of Climate Change" by Phil Wickens, a British marine biologist. After blitzing us with graphs, he delivered the facts. "Climate change is having its greatest effects in the polar regions," he said. "We're seeing the warmest temperatures for four decades and most scientists agree it is induced by humans."

He talked us through the problems of the Arctic: thin atmosphere, diminishing sea ice, melting glaciers. "Spitsbergen's ice could disappear this century, Greenland's ice cap melting is not beyond possibility. There could be a sea ice-free Arctic in summer 2030."

That, he said, would be fatal. "Polar bears will gravitate north as the ice breaks up – that could last a few decades – and then where will they go?"

We'd seen sea ice off Greenland. In the fog it looked sinister but now I knew it was the basis for the whole food chain, from tetrapods and algae up to that big white bear.

Finally, on an island near Monaco Glacier we spotted a female polar bear with two cubs. There was elation among passengers and relief for the tour guides. But Phil pointed out that the mother was too skinny and one cub looked like a runt. How thrilled can you be to see a doomed species in the flesh?

At 80 degrees north, we watched a solitary walrus slobbing around on Moffen Island. Nansen opens Farthest North with a litany of the trials suffered by 19th-century explorers just to get to 71, 73, then 76 degrees north. Yet here we were at 80, drinking hot chocolate laced with Tia Maria.

When we disembarked at Longyearbyen, I felt satisfied and ready for home, but pensive. Gary had said he'd chosen to be a dog-musher because it was his dream "and when you pursue something, everyone tries to put you off, it is all about what you're here for".

The distance between the man from Walthamstow's gutsy carpe diem attitude and my own was vast, like a blow to the ego, or the conscience. I didn't want to emulate his physical feats, but I decided to pack in the carbon-heavy megatrips. Greenland had been a reminder that humans are not everywhere (yet), while the polar bear had taught me the paradox of wanting to see something when your presence is part of the problem. Not a bad Arctic geography lesson, really.

Arctic essentials

Chris Moss travelled with Quark Expeditions, booked in the UK through Exodus. The 15-day Iceland, Greenland and Svalbard cruise costs from £4,990pp, which includes meals, Zodiac landings, lectures and shared cabin and shared loo, as well as stays in the embarkation and disembarkation ports and transfers to/from the airport/ship. Kayak excursions cost approx US$500 extra. Add US$200-300 for drinks and $300 for tips. Next departure August 9, 2012. www.exodus.co.uk

Flights

Icelandair (www.icelandair.co.uk) flies from London Heathrow to Reykjavik from £132 one-way; SAS (www.flysas.com) flies from Longyearbyen to Heathrow (via Oslo) from £159.50 one way. Prices include taxes.

Further reading

I'm With The Bears, edited by Mick Martin (Verso), a new collection of ecology-themed short stories by authors such as Margaret Atwood, David Mitchell and Helen Simpson.

For more about Gary Rolfe's life in Greenland, see garyrolfe.com.