What to Know About Canada’s Exceptional Wildfire Season

Canada is burning.

That, at least, is the perception around the world as hundreds of fires have convulsed the country, forced tens of thousands of people to flee and sounded a global alarm about the perils of climate change.

In a nation famed for its orderliness, the out-of-control fires have created the ominous feeling of a country under siege, stretching from the west to the east coasts and sending toxic plumes over major cities like Ottawa, the capital, Toronto, the largest city and financial capital, and Montreal.

As the smoke poured into the United States, disrupting life around the Northeast, and turning New York City’s skyline an apocalyptic orange hue, the fires also underscored how environmental disasters don’t obey borders.

Here’s what you need to know about the fires and Canada’s wildfire season.

Wildfire season started early this year.

While wildfires are common in spring and summer in much of Canada, they usually burn in remote and sparsely populated areas. But this year’s fires have already been remarkable: Hundreds are burning across much of the country.

A dry, windy and abnormally warm spring created ideal fire conditions in many regions with the first major fires erupting in May in Alberta, an oil and gas producing province that is regularly plagued by fires.

So far, more than 2,300 fires have consumed about 9,142,899 acres of forest, far higher than the 674,357 acres that burn, on average, by this point in the season.

The fires are likely to multiply.

The Canadian government forecast shows all of the country at an above average risk for wildfires for the rest of June. Ontario and British Columbia have seen relatively limited fire activity, but most experts anticipate that will not last. But not all parts of the country will be affected; the Arctic regions above the tree line are too cold for trees.

The distribution of the major fires is also unusual: from Alberta in the west to Nova Scotia on the Atlantic coastline, three time zones away. The smoke that’s plagued the United States is mostly blowing down from areas in Quebec that are not normally associated with major wildfires.

What started the fires?

Lightning typically sets off about half of Canada’s wildfires each season. Those fires are generally the most damaging because they tend to start in remote areas and are difficult for firefighters to access. They account for about 85 percent of the forest that is burned most seasons.

Humans are to blame for the other half of the fires not caused by lightning, setting them off in a variety of ways, usually unintentionally through carelessness. One of Alberta’s fires this year started when an all-terrain vehicle burst into flames. Some provinces have closed parks and forests to people and have banned camping and all outdoor burning to limit risk.

In past years, sparks from trains braking while descending mountain passes have also caused fires.

What role has climate change played in the fires?

Climate research suggests that heat and drought associated with global warming are major reasons for the increase in bigger fires.

Canada has the world’s largest intact forest ecosystem, and many parts of the country have experienced drought and high heat recently. That can make trees vulnerable to fire and can dry out dead grass, pine needles, and any other material on the bottom of the forest floor that can act as kindling when a fire sweeps through a forest.

Wildfire experts see the signs of climate change in the dryness, intense heat and longer fire season that have made these fires more extreme and are likely to do so in the future.

When will the smoke subside?

Smoke patterns, like the fires themselves, are weather dependent. In cities that have spent days dealing with smoke and ashen skies, relief is on the way.

Rain and cloud cover near wildfires in Ontario should improve air quality in Toronto.

Steven Flisfeder, a warning preparedness meteorologist at Environment and Climate Change Canada, said that the weekend could improve air quality in Toronto, thanks to some rain and cloud cover near wildfire areas in Ontario.

Catherine Brabant, a meteorologist at Environment Canada, said it did not appear that wind patterns will shift the smoke plumes toward Quebec’s biggest city, Montreal.

But with fires growing in frequency and intensity, experts say smoke filtering down into the United States may become more common.

Why is Canada’s firefighting capacity so stretched?

Canada does not have a national wildfire fighting force but relies on its 10 provinces and three territories.

In normal times a coordination center shuffles firefighters and equipment like water bombers and helicopters from provinces with few fires to crisis areas being convulsed by blazes.

These, however, aren’t normal times.

The scope and scale of this year’s fires is making it difficult for provinces to share firefighters and equipment and the system is stretched to the limit.

To help ease the strain, over 1,100 firefighters have traveled to Canada from abroad, including groups from France, Chile, Costa Rica, the United States, Australia, New Zealand and South Africa.

Vjosa Isai contributed reporting.