Tuesday, August 15

Why British Columbia's wildfires have been devastating

Before we dig into the story here are three of the latest (August 14) reports on the long running up-and-down crisis:

The Weather Network: 'Dry lightning' worsens B.C. wildfire crisis

CBC News: Evacuation orders downgraded for Canim Lake and Hawkins LakeSuccessful firefighting efforts over the weekend mean some Cariboo residents can head home

Coast Mountain News: BC government offers support for ranchers impacted by British Columbia wildfires

And this from The Seattle Times on August 2:  Why so much smoke in Seattle from B.C. wildfires? "Nature’s air conditioning" is broken, weather service says. Thanks for letting us know.

All right, now it's time to turn to an August 11 report by Mika McKinnon, published in New Scientist. McKinnon provides the best insight so far on why British Columbia's wildfires outbreak has done such incredible damage. Yet for readers who've been following my posts over the years on the Three Ds -- drought, desiccation, and desertification -- and on wildfires, there's nothing unique about the story; it's always a set number of factors combining in slightly different ways and playing out all over the world. And now in a Canadian province:

Fighting to breathe in the face of Canada’s wildfire emergency

Shifting winds and an atmospheric wall of high pressure have funnelled smoke into the city of Kamloops in British Columbia, filling the air with an unprecedented 684.5 micrograms of fine material per cubic metre. That’s nearly 70 times more than the World Health Organization’s guidelines for safe exposure limits.

My eyes sting when I walk outside, and I feel the throb of a headache coming on if I dare walk as far as the street corner. Even indoors, the smell of smoke whispers through the ventilation systems until it clings to everything. I woke up to ash on my toothbrush, large black flakes against white bristles.
Fuel to the fire

The story of how things got like this is a slow-speed disaster of climate change, a beetle invasion, and the unintended consequences of well-meaning policy gone wrong.

British Columbia is a mountainous, highly forested province in western Canada. More than half of the province is forest, with lodgepole pine dominating every ecosystem except the alpine tundra. “It’s a tree that is really everywhere in BC,” says Perrakis.

Over the past century, the forest industry has transformed native forests into denser, more homogenous stands by suppressing fires and selectively replanting the most economically valuable species after harvesting. “They weren’t nefarious policies at the time, based on what was known,” says Perrakis.

But one unintended recent consequence has been a province-wide bark beetle outbreak that has devastated the region’s forests – with the dying trees heightening the fire threat.

The dense, homogenous stands of lodgepole pine allowed native mountain pine beetles to spread quickly, while a changing climate reduced the severity and duration of cold winters that historically kept the beetle population in check. The infestation hit its peak between 2006 and 2008, although it has begun to slow down in recent years.

I’ve grown accustomed to seeing the once-green mountain slopes spotted with beetle-killed trees: first, one pine turns red as it dies, then more and more follow in speckled waves. Between six months and four years later, depending on individual circumstances, the red needles drop, leaving trees that look like grey, dry skeletons. 

Now, over 11 per cent of the province is covered in a forest graveyard of dead trees.
Red hot

The dead trees in the “red attack” phase are already known to pose a high fire risk. “We saw fire spread rates two to three times higher in these red-attacked stands,” says Perrakis. Fires burned quickly through the dry tree crowns, racing ahead of firefighters’ attempts to contain and control them.

But starting around 2011, forests became dominated with the grey tree skeletons – and we don’t yet fully understand how this “grey attack” phase affects wildfires. The situation is complex, with various competing factors either helping or hindering fires.

Without needles, fires no longer spread through forest crowns, but “underburns” racing along the ground are still common as new plants take over the forest. Fire-resistant aspen are taking over some hillsides, whereas highly flammable black spruce is growing in others.

Now when a fire starts, it spreads through a new mix of plants, and the dry wood of the beetle-killed trees adds to fire intensity and smoke production. “The dead trees fall over much more easily, sometimes even with just a breath of wind,” says Perrakis. This increases the danger to crews working in these stands.
Going on burning

This year in British Columbia, over half a million hectares have burned since 1 April, and with 126 fires still burning, that number may keep growing before the snows come. With slow starts to milder winters, that might not be until December. And we have no guarantees that this same disaster won’t unfold again next year, or the year after that.


Another report at New Scientist (How [Australian] Aboriginal knowledge can help the world combat wildfires), most of which is behind a subscription paywall, notes that every year wildfires burn an area the size of the country of India. "... and their economic and social impacts are felt far beyond their scorched boundaries. They release huge amounts of carbon dioxide into the atmosphere – and as Earth warms, they are on the increase."

But a connection between warming and forest fires says nothing about "unintended consequences of well-meaning policy gone wrong," does it?

We're learning more about the unintended consequences, aren't we, as we're learning a little more about the enormously complex issue of wildfires and their connection to the life cycle of forests, about which much is still unknown.

I knew nothing about the debate regarding wildfire suppression until I watched Nova's riveting 2002 program, Fire Wars (now available on YouTube). And it wasn't until a couple years ago that I knew anything about the connection between bark beetles and forest fires; I didn't even know until then that the beetles could do so much damage to forests.

Little by little. It takes time for specialized knowledge to work its way into general knowledge; this holds true no matter how important the topic. But if you think about how much you know about drought today and what you knew about it a decade ago, you'll see much reason for hope about the human race's chances. 

The perennial problem is passing along knowledge that shouldn't get forgotten in the shuffle of the day's news.

Humanity suffers from forgetfulness -- both our Achilles Heel and saving grace.  


No comments: