“As global warming evolves, the resiliency of the basin and its ecosystem, and the resiliency of its hydrology, is going to be reduced.” Henry Vaux resource economist at the University of California, Berkeley

VANCOUVER—Alexander Mackenzie kept a careful record of his troubles 224 summers ago, scribbling about torments like cold, driving rain and clouds of ravenous mosquitoes as he paddled a bark canoe north to the Arctic.

For days on end in early June 1789, he journeyed along the shores of Great Slave Lake, blocked at each turn by ice, searching with native guides for a route to the river that would eventually take his name.

Some 600 kilometres south of the Arctic Circle, lake ice was a constantly shifting barricade, frustrating Mackenzie’s breakout on an epic voyage that would carry him 4,241 kilometres north to what he called the Frozen Ocean.

Today the country’s longest river is a vague memory from social studies class for most Canadians, a remote place out of sight, out of mind.

But international scientists say the Mackenzie River and its tributaries, stretched across a sprawling basin that occupies nearly 20 per cent of Canada, plays a crucial role in cooling a warming climate.

“It tends to act as a climate stabilizer,” Henry Vaux, a resource economist at the University of California, Berkeley, said in a telephone interview.

If growing threats to the Mackenzie watershed aren’t better controlled, “loss of the refrigeration capacities of the basin is simply going to feed further warming,” he added.

Covered in ice

As Mackenzie navigated in and out of Great Slave’s bays, hunting for the river’s headwaters, a dream of riches lured him on: he wanted a route to expand the lucrative fur trade for his bosses at the North West Company.

Ice kept getting in the way of progress.

“Towards noon,” Mackenzie wrote on June 12, 1789, “our old Companions (the Muskettoes) visit us in greater Numbers than we would wish as they are very troublesome Guests.

“The Ice moved again in the same direction. I ascended a Hill close by, but could not perceive that the Ice had been broke in the Middle of the Lake.”

More than two centuries later, Great Slave Lake wouldn’t have gone any easier on Mackenzie, even though overwhelming scientific evidence shows the Arctic is warming faster than anywhere else on Earth.

About 80 per cent of the lake is covered in ice, and the figure has been that high for five of the last 11 years, reports Gaetan Langlois, superintendent for ice and marine satellite analysis at the Meteorological Service of Canada.

The early June ice cover dropped to a low of 10 per cent in 2006, but experts caution that climate is variable, so short-term variations say little about the broader problem of climate change.

The big risk is a kind of death spiral for the river system, as a warming climate and the impact of development reduce the Mackenzie’s power to moderate temperature shifts, and a once mighty river suffers even more.

“As global warming evolves, the resiliency of the basin and its ecosystem, and the resiliency of its hydrology, is going to be reduced,” Vaux said.

“Which means that its capacity to respond to the kinds of things that economic development results in is going to be lessened. Which means that the damages from those kinds of activities will grow.”

Giant heat pump

Vaux chaired an international panel of experts for the Rosenberg International Forum on Water Policy. They studied numerous threats to the Mackenzie basin, at the request of the Toronto-based Walter and Duncan Gordon Foundation.

The Mackenzie River and its tributaries function like a gargantuan heat pump, pulling warm water north, and helping to cool the basin, whose ice, snow and permafrost play a crucial role in the global climate.

“There is not a person on Earth who is not affected by what ice does,” because it reflects huge amounts of the sun’s heat, the Rosenberg Forum says in its recent report.

Long-term changes in snow cover in the Mackenzie River system will spread “well beyond that basin to alter snow and ice cover and other controls of climate regionally and globally,” it adds.

The Mackenzie pours so much water into the Beaufort Sea that it has a major impact on northern currents, Vaux said.

“And a change in those flows, or a change in the temperatures, could result in short-term changes in the ocean currents, and those would have a widespread, and profound effect, on climate,” he added.

Some call the Mackenzie “the Amazon of the North.”

Forest covers around 63 per cent of the Mackenzie basin, most of it virgin timber, and wetlands vital to numerous species of migratory birds and other wildlife make up another 18 per cent.

But around 400,000 people also live in the basin, mostly in Alberta, and many of them are living off the oilsands boom that is one of the biggest environmental hazards for the Mackenzie and its tributaries.

A byproduct of oilsands production is toxic waste, including arsenic, mercury, lead and benzine, which is stored in vast tailings ponds.

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They cover more than 170 squares kilometres, according to the Mackenzie River Basin Board, set up by Canada, British Columbia, Alberta, Saskatchewan, Yukon and the Northwest Territories to help protect the Mackenzie watershed’s ecology.

Researchers have found high levels of toxic pollutants linked to the oilsands in the Athabasca River, fed by glacial meltwater in Jasper National Park that eventually flows into the Mackenzie and north to the Arctic.

The river system’s hydroelectric potential, estimated to equal the rest of Canada’s combined, is another threat to the Mackenzie’s future.

Many of the river’s tributaries and headwaters have been dammed for power, flood control and irrigation, and more dam projects have been proposed, despite decades-old damage from northern B.C.’s W.A.C. Bennett Dam.

The dam, built on the Peace River in 1968, “has clearly reduced seasonal variations in water levels in both the Peace and Slave River deltas, resulting in ecological damage,” the Rosenberg Forum report says.

Its experts aren’t opposed to mining and other development in the region, but want closer scientific monitoring and a stronger Mackenzie River Basin Board to end jurisdictional disputes that endanger the watershed.

River of Disappointment

Mackenzie and his party found the mouth of the continent’s largest north-flowing river on June 29, 1789.

The local Dene people already knew it as the Deh Cho, or Big River. Mackenzie hoped it was a route to the Pacific Ocean. When the river delivered him to the Arctic Ocean instead, he named it the River of Disappointment.

Mackenzie finally made it to the Pacific coast, by way of the Peace, Fraser and Bella Coola Rivers, in 1793. His continental crossing beat the American Lewis and Clark expedition by a dozen years.

The fur-trading North West Company was paying Mackenzie’s travel expenses, so naturally, the final pages of his journals focus on how to make money from the wilderness he crossed.

When Mackenzie wrote of “the Barren Grounds,” the vast northwest territory from Hudson’s Bay to the Rocky Mountains and north to the Arctic seas, climate change was also on his mind.

He wondered whether tree cutting had enough of an impact on climate to explain why places at the same latitude were warmer in Europe than in Canada. He decided a more powerful, mysterious force must explain it.

“I myself observed in a country, which was in an absolute state of nature, that the climate is improving; and this circumstance was confirmed to me by the native inhabitants of it,” Mackenzie wrote.

By improving, he meant getting warmer, more like civilized Europe.

Such good fortune had to come “from a predominating operation in the system of the globe which is beyond my conjecture, and, indeed, above my comprehension,” the explorer decided.

And it “may, probably, in the course of time, give to America the climate of Europe,” Mackenzie predicted, sweetening his pitch that British commerce ought to move fast to cash in on the Barren Lands.

He set the stakes high: full control of the fur trade, all the way up to the North Pole, except for bits the Russians ran in the Pacific.

And then there were the vast fishing rights in two oceans “and the markets of four corners of the globe,” Mackenzie gushed.

His voice echoes louder today, as northern temperatures rise and pressures build to profit from the rich resources in the watershed he explored, increasing the dangers that one day it may be destroyed.

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