Last week, smoke from wildfires in Washington and B.C. reached Saskatchewan. Air quality in Calgary was worse than that of Beijing. Alberta Health Services issued advisories. The City of Calgary prohibited backyard fires and promised $10,000 fines for violating the ban.

In B.C., the Rock Creek fire burned down 30 houses, 15 other buildings and forced several hundred persons to abandon their homes and flee. Forest animals, from the fleetest whitetail deer to the slowest badgers, suffocated when the fire consumed all the ambient oxygen. Their carcasses feed crows. The Rock Creek fire was likely caused by a cigarette butt.

The Okanagan complex fire is the largest in the history of Washington. Last year’s fire was the second largest. Three towns were evacuated, 50 houses and 60 other buildings were burned. Three firefighters died and four more were injured. The governor called it an “unprecedented cataclysm.”  It was started by lightning strikes.

Both fires were very hot, which provides a clue as to why they were so devastating. First Nations and Native Americans traditionally burned the woods, usually in winter, to preserve and regenerate vegetation. Today, foresters seldom disturb the forest by setting it alight in a more or less controlled way.

One consequence is that the woods fill with debris, from dead trees to impenetrable undergrowth. Fire suppression, the triumph of Smokey Bear, has caused a huge problem of fuel loading. The result: too many, not too few, trees. So when forests burn today, they have plenty of fuel to cause catastrophically hot fires that sterilize the soil, destroy watersheds and boil streams.

Officials on both sides of the line have known for years about overstocked forests and the cause: a prohibition against human disturbance of the woods. Here is where things get interesting.

The Sierra Club wants to end all logging on federal public lands in the U.S. Greenpeace has testified before the UN Intergovernmental Panel on Forests (a malignant twin to the Intergovernmental Panel on Climate Change) that everyone needs to adopt “environmentally appropriate substitutes” for wood. But as Patrick Moore, who co-founded Greenpeace before they went goofy, noted: “no list of substitutes is provided.” Why not? Well, because there aren’t any.

So why do such environmentalists want to close the woods to commerce? So far as I can see, they have advanced three reasons, all of them specious.

The first is that forestry causes entire species to go extinct. The poster-child for this conceit is the northern spotted owl. Computer models indicated that it needs old growth trees to flourish. But these “desktop extinctions,” as Canadian journalist Elizabeth Nickson called them, do not exist in the woods. There, spotted owls flourish in second- and third-growth forests and grow fat on a diet of dusky-footed wood rats that relish life in new forests.

The second reason is that the environmentalists think that natural disturbances, such as mega-wildfires, are O.K., but human ones, such as logging, are fundamentally different and very, very wrong. Of course, logging is not the same as fire and both are different than volcanic eruptions. No two fires are identical. And yet, forests recover when fires go out, when volcanoes stop erupting, and when loggers leave the woods.

The third is that they see ancient forests as sacred green cathedrals, not decaying vegetation that could become two-by-fours before it turns into fuel. Old-growth forests have always been part of a cycle and never existed by themselves.

So here is a question: How many environmentalists have a clue that their pseudo-religious nonsense is responsible for the thick air last week?