For the better part of more than four decades, when the summer arrives in Canada, my mind wanders north, to the Arctic. It’s been this way since I was invited to join friends to canoe the South Nahanni in 1977 – a legendary river that flows southeast for more than 500 kilometres through some of the most spectacular landscape this country has to offer.

On that first trip, I remember paddling through canyons, staring up at 2,000-foot walls that felt almost otherworldly in their construction. The route takes you past Victoria Falls, which spills over a huge hill of pre-Cambrian rock higher than Niagara Falls, and then continues rapidly (one must avoid a killer whirlpool only slightly smaller than the one on the Niagara) before joining the Liard River; which then converges with the Mackenzie River, which flows into the Beaufort Sea. It was an unforgettable voyage.

In the decades since, I have made more than a dozen trips to the Arctic, most of them in July and August. I wish more people in Canada had the chance to visit, no matter the time of year. I’ve always found it strange how one of the most incredible places on the planet is in our own backyard, and yet, when it comes time to travel, we often look elsewhere. Why is that?

The Arctic is in many ways the soul of Canada. If you aren’t thinking about it now, you will no doubt think about it soon. This soul is threatened both by climate change and a shifting geopolitical landscape. The Arctic is under siege, and will serve as the stage for one of the most fascinating and high-stakes diplomatic battles in the coming years.

In 1978, I paddled the Noatak, in Alaska, and then, in 1979, the Hanbury and Thelon Rivers, which join together and finally empty into the northwest corner of Hudson Bay. I could rattle on about the Hood River, the Back, Burnside, Wind, Isortoq, Thomsen, Koroc and many other rivers that, over the following years, were paddled by a group of us who looked for rarely travelled rivers with some challenging rapids, and, preferably, notable wildlife: birds, animals and fish.

We did the ones we thought would be interesting: from Alaska (the Noatak), all the way across the continent to Ungava Bay (the Koroc). We also tackled rivers on Banks Island, Baffin Island and the Melville Peninsula. The one I regret having missed was the Ruggles River, which starts at Lake Hazen, which was solidly frozen when our merry band arrived at the north end of Ellesmere Island, and flows into the Lady Franklin Basin and/or the Kennedy Channel near Fort Conger, and is about 481 km from the North Pole.

In total, our core group paddled 25 rivers, most near to or well above the Arctic Circle. Our pickup rendezvous with chartered Twin Otters were nearly always in the saltwater of the Arctic Ocean.

The feeling of immensity is what strikes me most in the Arctic. That, and its fragility. Wild rivers and forbidding rock formations contrast with miniature plants that survive with barely a growing season. Flowers are astonishing in this environment. I always feel great privilege and a sense of freedom in this seemingly pristine landscape, although I wonder if pristine is now an obsolete word in our world.

It’s a land that can seem empty for miles and miles, which makes the sight of the world encroaching that much more jarring. To get to the Noatak in 1978, for instance, we flew across Canada to Whitehorse, and caught a flight to Fairbanks, Alaska. Early the next morning, we were at the airport loading a single-engine Beaver, and were shortly on our way to Bettles Field, Alaska, a refuelling stop, and then on a north-by-northwest course to Williams Lake, Alaska, a puddle-sized lake close to the Noatak, which rises in the Endicott Mountains, and makes a sweeping arc westward about 160 km north of the Yukon River and roughly parallel to it. It empties, finally, into Kotzebue Sound, a southern section of the Chukchi Sea.

The land we flew over on the last lap was mesmerizing; but I started to feel uneasy when I saw the oil pipeline from Barrow, at the northern-most tip of Alaska, snaking south to the tanker-loading area northwest of the Gulf of Alaska, near Anchorage. The brutal strength of it was admirable – in the sense that it was a remarkable achievement. But the rough shape of it looked more like a raw, painful, unhealed scar hacked into the landscape with an axe. Even then, decades ago, I feared we were doing irreversible harm to the land. Flying over clear-cut forests has the same unsettling effect.

Most canoeists like a young river, one in its early stages of becoming a major river; the young Noatak was a delight. Wading birds skittered up and down the river banks, we heard the shrill cries of bald and golden eagles, gulls, jaegers, killdeers, plovers and, as the evening dusk began to gather, howling wolves on the other side of the valley serenaded us as we prepared our first evening meal in Alaska. The sun still provided light enough to read, cook, take pictures and enjoy our first happy hour, which our putative leader, the political commentator Craig Oliver, stirred up with lime juice, over-proof rum and more water than we (collectively) thought necessary.

Once we got below the shallow waters of the narrow rivulet that the Noatak was at its outset, it produced all sorts of curiosities: pingos, for example: the exoskeletons of small land-formed icebergs. Pingos are usually the earthen shell of ice that has melted and left a rigid, empty ball of dirt – a curiosity that is a pleasure to behold, but difficult to climb. When the winter ice breaks up and is carried downstream, the water forms all sorts of miraculous and surreal shapes and forms – a virtual gallery of Henry Moore sculptures made of ice lined up on both banks to entertain us as we paddled past.

Over the years, we noticed that winter ice did not linger long and we rarely saw the Henry Moore exhibitions that had been such a delight to photograph and admire. We still saw herds of caribou, occasional grizzly bears, Arctic foxes and Arctic hares; but we also noticed that things were changing.

Our trip down the Hood River in 1980 was a case in point, since the temperature was pleasantly warm the entire time. But when we reached the saltwater of Bathurst Inlet, even at 9 a.m., my thermometer registered an astonishing 32 degrees. The sky was clouded with smoke from wildfires 1,200 to 1,400 km to the south in Alberta, the sun was a blood-red ball in the sky, and the plane that was due to pick us up was a day late because of heavy smoke it had to fly through to get to our agreed-upon rendezvous.

A more compelling example was our last trip on the Back River in 1998. We met our pickup plane as scheduled at the mouth of the river in Chantrey Inlet on the Arctic coast. Once loaded, we flew to Gjoa Haven on King William Island to refuel, and then landed at Starvation Cove on the Adelaide Peninsula. It was a wonderful summer’s day, warm and sunny, not an ice cube in sight. From this sad place in March of 1848, 105 of Sir John Franklin’s men left this desolate corner of the Arctic to walk south up the Back River hoping to reach one of the northern Hudson Bay posts. None of them survived.

We were there 150 years after the British Admiralty sent three expeditions to search for the missing ships. Sir James Clark Ross’s expedition was the closest, but the ice was so thick that all efforts failed. His ship was stuck from the spring of 1848 until finally drifting out of ice in the summer of 1849.

Things were certainly changing, as ice melt is rapidly accelerating, more quickly and drastically than any of us could imagine. That was more than 20 years ago. I shudder to think what it will look like when more and more ships can get through Arctic waters without ice-breaker assistance.

For us, the canoeing days in the Arctic are pretty well over. What we do best these days are reunions and slide shows. We talk about the Arctic passionately – its glories, magical landscapes, tricky or dangerous rapids, hot springs and adventures we enjoyed there.

We also talk about the geopolitical developments in the Arctic, which have now reached a point that could be described as a potential crisis that could explode into something much worse, given the key players are Russia, the United States and China. (In January of 2018, China’s “President for Life” Xi Jinping, announced his plans to create a Polar Silk Road (an extension of its ambitious, globe-spanning Belt and Road Initiative) that wends its way across the Arctic Ocean. China is not an Arctic country, but never mind; they consider themselves a “Near-Arctic state.”)

More pressing is the impact of climate change.

I returned last summer with my wife, Linda – a cruise, not a canoe trip, although she and I have also canoed together in the North. The contrast between what we saw from the observation deck of the Silver Cloud or from kayaks, was enormous. We were excited and enthralled by the icebergs drifting slowly past, and then we were engulfed by the unforgettable, magnificent splendour of the Arctic landscapes that stretched for miles in every direction.

A huge herd of walrus and the occasional polar bear were a highlight. But, beautiful killer whales (orcas) were troubling. They are now much further north than they have ever been. The orcas are tracking food in areas now accessible owing to melting ice. It is a likelihood they will soon be killing polar bear cubs. Once the prime predator of the Arctic realm, the polar bear may soon take second place as the most dangerous of all animals in the High Arctic. And, it’s humans, not the orcas, who have created the problem.

The warming of the planet has had a severe effect on the tundra and, with the current warmth melting, not just the tundra. Global warmth is now reaching deep into the permafrost and the rate at which methane is being released from the permafrost into the earth’s atmosphere is accelerating the warming trend sharply and alarmingly.

The consequences are clear: more wildfires, longer droughts, super-high winds, species extinction, rising oceans, more frequent disasters, have already been predicted by science experts and experienced in places such as California, where the Livermore Laboratory, almost a year ago, determined that the loss of Arctic sea ice will result in the consequences just mentioned. Lakes in the area of the Noatak River can be seen bubbling like fury with escaping methane, the most powerful of the greenhouse gases that destroy the ozone layer, which protects the Earth’s atmosphere.

The Arctic leads one to a much humbler understanding about one’s own life and its meaning. The experience of seeing and travelling in the Arctic pushes one into thinking about the infinite eons that life here has endured, about the immensity of the universe, and the hope that the Arctic will endure for many eons still to come.