Research

Are there more forest fires or is the media more active in reporting them? Forestry Professor David Martell offers his expert opinion

There seems to be more news about forest fires and wildfires in places like California, Australia and parts of Canada. Why is this?

I don’t compile statistics on media coverage of forest fires, but there probably has been more media coverage lately because there have been more spectacular losses. But the phenomenon of wildfires wreaking havoc on people and forests and their homes is nothing new. If we go back to our early history, particularly in eastern Canada, Ontario for example, some of our worst forest fire disasters happened in the 1920s. More recently in Canada, most people would relate to the Kelowna and Barriere fires in the southern BC interior in 2003.

California makes the news on a regular basis — most often in the fall. Australia had problems in the state of Victoria in January and February. Almost 200 people died and more than 2,000 homes and some whole communities were burned. So that made the news. These kinds of problems also crop up every summer in the Mediterranean Basin — southwestern France, Spain, Portugal, Greece.

Why do we see more coverage than in the past? Frankly, it’s probably because we have better media coverage. We find out what’s going on in Australia almost as fast as the Australians.

For the most part, the newsworthy items are where people and homes are involved. When wildland fires start running, they often run through communities. Why? Well, in the fire business we talk about what’s called the ‘wildland-urban interface’ where people are building permanent and recreation homes out on the landscape. And when they build out there they don’t always take account of the fact that some landscapes burn.

So one of the reasons there is probably an increase in news reports is that more people are building more homes in flammable forest and wildland landscapes.

Also, at this time, every year, my phone usually starts to ring. As soon as the first big fire happens somebody calls up and says “Is this a sign of climate change?”

To the extent that we understand these large scale fire processes, we expect that fire activity will increase as a consequence of climate change. There is a link between climate change and fires and people are aware of that now.

Are wildfires different from forest fires?

They are and they aren’t. In Canada, we usually use the term “forest fires” because we have mostly forests that burn here, but in Southern California, they use the word “brush fires” because it tends to burn chaparral brush lands. They call them bush fires in Australia. How do they differ? If you get up in an aircraft and look at them burning in Northern Ontario, you’ll see tall trees burning, mostly pine and spruce trees, in Southern California, you’re going to look at what you’d think of as brush and in Australia and other parts of the world, you get forested areas where there are eucalyptus trees and a lot of grassland burning. All of this is wildfire.

When fire specialists look at landscapes, they see fuel, so they look at fuel types. A jackpine fuel type, for example, or a spruce fuel type. If you look at a fire in Northern Ontario, you’re looking at tall trees, with flames up to 50 metres high, whereas in Southern California, the flames aren’t as high because the brush that’s burning is lower in height.

There are differences in the way these fires burn. In northern Canada, they burn like large, marching fires with a continuous front and they could burn, say, five to eight kilometers an hour.

But Southern California has its most severe problems when they have Santa Ana winds.  Continental atmospheric wind circulation patterns become established and they get a dry wind coming from the continent and pushing toward the coast and you get very high speed and very dry winds. The flames are bent over at 90 degrees, it’s like burning in a wind tunnel, incredible speed and intensity. In Australia, they have eucalyptus and some kinds of eucalyptus have bark that is conducive to what is called “spotting” — dry, stringy bark that catches fire, and then the wind picks it up and throws it way ahead of the main fire.  So it could easily start new fires, five or 10 kilometres ahead of the original fire.

For any fire, you need flammable vegetation that is dry enough and pushed by a strong steady wind to get the kind of crises you see in the news.

How do they start?

There are two main causes of forest and brush fires — people and lightning. In Ontario lightning accounts for about 35 per cent of the fires. About 65 per cent are caused by people. There’s a disconnect because most of the area that is burned is burned by lightning-caused fires. Most of the fires are caused by people, but lightning burns more area.

Among those people-caused fires, there’s an interesting element that you certainly heard about in Australia in that some of those fires are believed to have been arson fires. I don’t know the proportion in Australia, but some were suspected to be arson. We know there is a significant arson problem in some parts of the United States, but there’s not much arson in Canada with forest fires that we’re aware of.

What’s the forest fire season looking like this summer in Ontario and Canada?

Ultimately it’s determined by the weather. But a number of things have to come together. We tend to have two types of fire seasons in Canada. We have a spring season before the new deciduous tree leaves have emerged and “greened up” the forest, when you have a lot of dead leaves from last year. The new deciduous forest hasn’t yet come out, so the sun bakes the forest floor. Someone’s out fishing or something and starts a fire and there’s a potential to have large, person-caused fires. You have a hot dry day with some wind and someone makes a mistake that causes a fire.

The second season is with lightning fires. The question is do you get them during a period of prolonged drought or when it has been more normal weather? You can get a whole lot of lightning fires, but they don’t do a lot because there hasn’t been drought to precede them or they’re spread out over time so fire organizations are not overwhelmed and most of the fires can be contained by fire fighters.

Climatologists believe that if they study sea surface temperatures in the Pacific ocean, and to some extent in the Atlantic, they can make long term predictions — in the order of months — about general atmospheric wind circulation patterns and the extent to which storms will affect different parts of the country. This is more accurate in the west than the east, because the west is closer to the Pacific.

If you look at the latest weather predictions that have been issued by some of the weather agencies, they’re suggesting some hot, dry weather in parts of western Canada as far east as Manitoba. In other parts of Canada, they’re looking at fairly normal temperature and precipitation. So to the extent that someone has made a prediction as to where hot, dry conditions might materialize, there are people who are suggesting forest fires might happen in western Canada, but the fact of the matter is, from the standpoint of the fire business, three or four days of good drying weather and the ignition of fires can create a one-week fire season that you really can’t anticipate more than a week ahead.

• Professor Martell’s website
• “Of Forest and Fire”, Edge Magazine article about Professor Martell

Tags: Behind the Headlines, climate change, David Martell, Environment