The cold water burned me to the bone. The salt stiffened my hair and slicked my skin. As I surfaced in the heavy mist, I could hear shrieks of delight from the other adventurers doing full-body dunks into Antarctica’s waters. The black shore’s sharp sulphur seeped into my lungs. That was January. In August, I had survived swimming in the Arctic. Two Poles, two edges of the ocean within half a year.

I’ve done a lot of travelling over the past decade to understand how humans are affecting the planet and its systems. I’ve written scores of articles trying to explain what I’ve found as well as a couple of books, done field research with scientists on all the continents and even dived 3,000 feet to the bottom of the sea in a submersible. But nothing has moved me like this half year of polar living. Nothing else brought home the power of the planet and the even greater power of our species to destabilize its workings. I’ve been so mesmerized that, in a way, I have stayed at the ends of the earth ever since.

Why? Because the Poles are change on fast-forward. Out of sight and out of mind, they are nevertheless the terrifying future of climate and ocean change. They are prophecy come true. What’s happening in those mysterious and forbidding extremities of the planet foreshadows what we can expect in our own backyards.

And not only foreshadows. Because of their ice and snow and the cycles of freeze and thaw they generate, the Poles regulate the planet’s temperature. They are its thermostats. As they change, they drive change in other parts of the world.

A little background. I was travelling as faculty with the Gatineau, Que.-based charity Students on Ice, the creation of the Canadian adventurer Geoff Green. He takes high school students from all over the world to the Poles and then lets them loose with experts to explore. So far, he’s taken about 1,500 in 10 years.

My first Pole, the Arctic, was supposed to be a one-time volunteer gig in August that would plug into two great loves for a couple of weeks: teaching teens and hanging out with scientists in the wild. Instead it set up a fierce longing in me to kneel on the continent of Antarctica and taste the Southern ocean spray on my lips. It was as if I could not be whole until I had understood these two planetary siblings that could not be further apart.

Strictly speaking, the Arctic is an ice-covered ocean surrounded by land. But the standard definition doesn’t hold up today because the polar ocean it isn’t covered by ice anymore, at least not in the summer.

The 120 or so of us on board the Russian ship M/V Orlova for 12 days steered across the top of Quebec into Hudson’s Bay and then doubled back to Baffin Island. We were on the eastern edge of the fabled Northwest Passage.

During earlier expeditions, the ship’s captain had used the Canadian Space Agency’s RADARSAT satellite system to make sure he didn’t get stuck in the sea ice. On our trip in August, the ship’s captain used RADARSAT to do the opposite – rather than avoiding ice, he wanted to find sea ice to show the kids what it looks like. He couldn’t find any.

This is more than a little unusual. The Arctic Ocean has been covered with ice for the past 47 million years. I remember writing my first article about human-caused planetary change in 2000 and reporting that the Northwest Passage might eventually thaw enough to be a shipping route in the summer. It was almost unimaginable at the time, just 11 years ago.

Back then, climate change scientists using supercomputers to make models of the future went out on a limb to say that the Arctic might be warm enough to be free of ice in the summers by 2100. A few predicted 2050.

Even they missed the mark. The melt has happened so fast that the models can’t keep up. Instead of changing in a sedate, linear fashion, it’s happening exponentially. Today, many of the models say that the Arctic will be reliably navigable the summer after next, 2013.

That matters because the less sea ice there is, the more black open water. The more open water, the more heat the water absorbs, leading to yet more loss of sea ice and greater warming of the air as the water gives up its stored heat. It’s a self-feeding loop. Last winter, air temperatures in the Arctic were as much as 12 degrees Celsius higher than average.

In turn, this is changing wind patterns from the Arctic, bringing frigid air and lots of snow to the middle parts of North America and other northern continents. It’s the so-called Warm Arctic, Cold Continents phenomenon. That snowstorm along the eastern seaboard after Christmas? Evidence that the planet’s Arctic thermostat is off kilter.

The ice is melting because the air is getting warmer, due to more carbon dioxide gas in the atmosphere from the burning of fossil fuels such as coal, oil and gasoline.

About 250 years ago, carbon dioxide made up less than 0.03 per cent of the volume of the atmosphere, usually expressed as 280 parts per million (ppm). Today, it’s more than 390 ppm, or nearly 0.04 per cent — dramatically higher than it’s been more more than 20 million years. The higher the concentration, the more heat the gas traps against the surface of the planet.

Signs of warming were everywhere in the north. About a third of the students on the trip were Inuit. They could catalogue changes to the land, air and water just in their lifetimes. The tree line at Kuujjuaq in northern Quebec, where several of the students live and where we caught our ship, has moved north. One day we hiked up a hill on Digges Island at the top of Hudson’s Bay, surrounded by clouds of mosquitoes, another newcomer brought by the warmth.

The kids talk about the robins they see now, the ice that no longer forms even during the winter in the harbours where their families used to hunt, the permafrost that’s no longer frozen, the spring that comes earlier than when they were little.

A small group of us cruised to within a dozen meters of a young male polar bear one day. He stood stock still on the shore of his island, snout pointed, staring at us with what might have been curiosity. His fur was the colour of butter. He was fat and glossy, but many in the North no longer are. They depend on the ice to breed, rear their young and hunt, and the ice is vanishing.

There are only 25,000 to 20,000 polar bears left on the planet. Of the 19 separate populations, eight are in decline, three are stable and only one is on the rise, according to the World Conservation Union. The others are too poorly studied for scientists to make a call but some experts are predicting that the last polar bear will die within decades. A generation ago, biologists worried that the big threat to the bears was the hunt. Now, it’s the heat.

It’s not just wildlife. Unlike its southern counterpart, this Pole has people and ancient cultures. We visited a Thule archeological site on the southern tip of Baffin Island, across the bay from the hamlet of Cape Dorset. In a meadow of flowers were the remains of oval earthen structures the Thule, forebears of today’s Inuit, inhabited as much as three millennia ago. Their sunken entrances kept out the cold so five or six people could sleep on a narrow shelf inside.

It felt peaceful. Off in the distance, some of the expedition kids were laughing and skipping stones. Next to the dig, the Inuit elder David Serkoak, dressed in his holy white robes, beat out an ancient rhythm on his skin drum, turning it first to one side and then the other like a giant resonant lollipop as his voice rang out, offering songs to his ancestors.

I couldn’t help wondering what will happen to modern Inuit and Inuvialuit as the Arctic warms. Already forced to adapt to centuries of rules made by the British, the churches and the Canadians, will the people of the North be able to adapt to the assault of carbon dioxide generated far away?

The day we piled into zodiac boats to find walruses really brought the scope of the problem home to me. Cruising around Walrus Island at the top of Hudson’s Bay, we had to strip off layers of fleeces, undergarments and shells. We were sweating in the heat of the day.

I smelled the walruses before I saw them. And heard them: honk, honk, whistle, snort. The smell attacked my nose and lungs, foul and fishy. And then there they were, nearly 1,000 on a single barren island, almost the same cinnamon colour as the rock. Except for their undersides. Walruses cool off by sending blood to their bellies. You can tell they’re too warm if their bellies change colour. Many of these were hot pink.

I watched them for a long time, marveling. They lumber on land, dragging blubbery bodies across the bare rock, the massive males rearing up to threaten each other with ivory tusks, crashing comically into each other and sometimes sliding into the sea in bunches like an avalanche. But once they hit water, they’re fast and sure, more poetic than goofy. One of them came up to the side of our zodiac, poked its head up out of the water and stared me straight in the eye.

Like the polar bears and most other polar wildlife, they’re in danger, too, because they depend on the melting ice. And it’s melting.

Back at the ship, the crew had filled the outdoor swimming pool with sea water and let it heat up in the midday sun. Most of the kids and some of the staff put on swimsuits and jumped in to cool off. Some even sunned themselves on the deck for more than an hour.

The Arctic, bikinis and sun tans. How is this possible?

A couple of days later in Kingnait Fjord off Baffin Island, we submerged ourselves in the ocean itself. It was shudderingly cold for me. But it was warm enough in the heat of that day that some of the kids frolicked in it until the time came to head back to the ship.

Back home, anxious and distracted, I tracked the fate of the Arctic sea ice through the autumn. A little before Christmas, the Washington-based National Oceanographic and Atmospheric Administration (NOAA) put out a report card saying that there was nearly one-third less sea ice through the Arctic last summer than the average through the 1980s and 1990s. And things were already warming up in those decades.

There isn’t as much snow on land anymore and it doesn’t last as long, the report card says. This summer set record high air temperatures across the Canadian Arctic and Greenland. As the Canada Basin absorbs excess carbon dioxide from the air, its waters are becoming acidic enough to corrode marine creatures’ shells.

The verdict: “Return to previous Arctic conditions is unlikely.”

My trip to Antarctica began two days after Christmas, in the Southern summer. Antarctica, which literally means the opposite of the north, is the more mysterious of the two Poles. No human eyes caught sight of the continent until 1820. No one reached the Pole itself until 1911 and no one lives there permanently. Larger than Australia, it contains 90 percent of the ice on the planet, some of which is as much as five kilometres thick and as much as a million years old. Only one percent of the continent is ever free of ice.

That ice matters. In the Arctic ice covers water, but in Antarctica, it covers land. When Arctic ice melts, it affects the heat balance of the planet but not the sea level directly, because the ice is already in the sea and already incorporated into sea volume. Like ice cubes in a glass of water.

If Antarctica’s land-based ice melts, it affects the sea level. That’s what happened in 2002, after the 500-billion tonne Larsen B ice shelf on the western peninsula of Antarctica calved into the ocean, stunning scientists and allowing land-based glacier runoff to flow into the ocean.

Scientists calculate that if all the ice on the Earth were to melt – including the 90 percent of it in the Antarctic – sea level would rise 70 metres. That would drown much of the Maritimes, New York, London, and all of Florida. Paris would be on the coast.

Understanding the effect of planetary warming on Antarctica is hugely important. And the Western peninsula of the continent is warming up faster than anywhere else on Earth.

To get to the peninsula, our expedition of 54 students and 30 staff spent two days crossing the notoriously turbulent Drake Passage from the tip of South America. We sailed through iceberg alley, surrounded by flat-topped icebergs as large as a kilometre and a half across, tinged turquoise.

Wandering Albatrosses, which have the widest wingspan of any bird alive – once hunted so men could make tobacco-pipe stems from their wing bones – swooped down to follow our ship. Humpback whales playfully leapt out of the water dozens of times just a few metres from our bow. Penguins tracked our wake, skipping in and out of the water like porpoises.

When at last we sailed far enough south to set eyes on the continent, it was wrapped in mist. I could barely tell the sea from the sky. The following day we zoomed up to Heroina Island in a zodiac, waded through icy waters in rubber boots and finally set foot on Antarctica.

Heroina Island, near the Western peninsula, is home to one of the world’s largest rookeries in the world of Adélie penguins: roughly two million birds live here, including the newborn chicks in rocky nests. The stench of penguin guano was almost unbearable. The whole island was caked with the stuff, and in the warmth that day, it was melting, running down to the ocean in deep-cutting rivulets.

I didn’t care. I knelt on the land, watching the penguins, listening to them caw and flap their elbow-less wings. They have no fear of humans and wandered over to check me out.

Those Adélie penguins were healthy. Most of them had chicks. I was close enough to see the egg-teeth on the chicks’ beaks, meaning that they were only a few days old. Last year, the colony was in much worse shape, the Argentine ornithologist Santiago Imberti told me. The birds were thin and few had young.

That’s one of the trends here. As the air and water warm up, the sea ice near this part of the continent is melting. With the melt go the tiny shrimplike krill that are key to the Antarctic food chain. With the heat, the penguins are moving further south to breed. But the summers further south are not yet long enough for them to raise their chicks.

There are other signs of profound change. Glaciers are in retreat across the Western peninsula. The Southern Ocean surrounding Antarctica is nearly as acidic as the Arctic from the carbon dioxide gas being absorbed from the atmosphere and is acidifying twice as fast as ocean water closer to the equator.

At Palmer Station, where scientists have been recording temperatures since the mid—1960s, the air has risen 6 C and water 1 C. One day while we were near there, the temperature topped out at 14 C. As had done in the Arctic, we stripped off layers of clothing to keep comfortable.

By the time we headed toward Deception Island, an active volcano in the ocean and a whaling station until 80 years ago, I was feeling grim. I hadn’t expected the signs of cataclysm to be so clear. I wanted to believe that the Poles are immutable.

To get to Deception Island, we sailed through a formation known as Neptune’s Bellows or Hell’s Gate. The volcano’s sulphur hung in the air as we approached the black beach. It was shrouded in mist. In the early part of the last century, whalers towed 100,000 slaughtered humpback and fin whales through that narrow channel and then rendered their blubber, bones and brains into oil in huge metal tanks.

The industrial and military appetite for whale oil was so voracious that whales the ocean over teetered on the brink of extinction until a global hunting ban was imposed after the Second World War. The fossil fuels that replaced them now endanger all life on the planet, humans included, an irony not lost on me as I neared the station.

I trudged off the zodiac onto this sooty beach, and then into one of the huge tanks still standing. Made from bands of riveted iron many storeys high, it is decaying now, returning to the earth. I looked up to see light streaming through holes in the roof.

Remy Rodden, a Yukon singer-songwriter who was on the Arctic trip too, was there with his guitar and harmonica. We were tentative at first, then he lifted his voice and the notes bounced and swelled and lingered, filling the tank with beauty. It became a cathedral where it was impossible to sing a sour note. We played there for two hours, making otherworldly harmonies, the notes seeming to vibrate through our very cells.

At the end, faces raised, fingers spread wide at our hips, he began channeling the whales with his voice. I followed, making sounds I never believed were possible. We made peace and joy in that terrible place, and it felt like redemption.

Moments later, my second plunge into polar waters, the taste of salt in my mouth, the stinging eyes, the bitter cold. Only to emerge and bolt toward a pit dug into the shore and filled with sea water that had been warmed from below by the earth’s volcanic energy.

There I lay, restoring warmth to my bones, cradled by earth, air, fire and water, shriven, and finally whole enough to imagine returning home.

***

This story first appeared in The United Church Observer’s April 2011 issue with the title “To the ends of the Earth.”