by
Mike Flannigan and Mike Wotton
Forest fires are a significant, natural and necessary element of Canada's boreal forest, yet when they threaten our values, such as our communities and timber resources, they become unwanted and we try to limit their extent through suppression activities. Fire's occurrence, spread and suppression are strongly linked with day-to-day weather. The changing climate will cause many complex effects throughout the world, increasing temperatures, changing precipitation amounts and frequencies, and altering basic weather patterns.
Research in Canada has shown that increases in forest dryness, due to increasing temperatures, will be expected over most of Canada's forest. With drier fuels, our forests will be more prone to fire starts and fire growth, although across a country as vast as Canada, there will be large differences in the size of these changes. Recent research has shown that under the climate changes projected for the 21st century, the number of forest fires will increase, driven strongly by increased lightning fire activity. This increase is estimated at more than 50 per cent by the end of the century; some regions will see greater increases than others.
Forest fire suppression organizations have great success when they can reach a fire soon after it ignites and contain it before it can grow in size. It is the small handful of fires that escape this initial attack, called "escaped fires," that become large and contribute to the vast majority of the area burned in Canada. Both the weather conditions driving a fire and the number of fires occurring in an area influence the ability of a fire management agency to contain a fire during the initial attack phase.
Research has shown that the increase in the number of fires occurring, and the increased fire spread potential accompanying future climate, will probably lead to large increases in the number of escaped fires. With the increased warming associated with climate change, we expect longer fire seasons. Therefore, fires may start earlier in the spring and burn longer into the fall.
In addition to an increased area burned in Canada, there are other interacting factors to consider, such as disturbance from insects, disease, blowdowns from wind or ice storms. These other forest disturbances, which change the fuels themselves, can magnify weather's influence on fire activity.
Canada's fire management agencies are as modern and efficient as any such agencies in the world. They have evolved to effectively manage the general fire load they receive. It is currently only the infrequent 'extreme' fire seasons, for instance, a year with an extended period of drought, that overwhelms them, leading to larger numbers of escaped fires and large areas burned. Research is quite clear that climate change will create conditions that will contribute to more forest fires throughout most of Canada. We therefore expect that agencies will soon experience more and more of these 'extreme' years. Years that challenge them and overwhelm current levels of suppression resources will become more the norm, leading to more fires burning the landscape.
While agencies might initially respond by increasing their resource levels with personnel and equipment, such as crews and air tankers, to meet the increased number of fires, analysis has shown that very large increases in resources are needed to maintain the current levels of effectiveness given even the modest changes in fire activity expected over the next couple decades.
Analysis of the initial attack system shows that there may be a substantial need for resources required to meet a modest increase in fire activity. It is doubtful that agencies can realistically be expected to expand to maintain the current amount of fire in the forest as we reach the end of the 21st century, given the large changes in fire activity that are expected. Through this next century, it is reasonable to expect that the forests of Canada will see more fire, and the values we have in the forest will be threatened more frequently. How we adapt to this increased presence of fire must include more than simply relying on fire suppression. It requires a rethinking of how much fire we can live with in our forests.
The Great Lakes Forestry Centre in one of five Natural Resources Canada - Canadian Forest Service centres across Canada.
Great Lakes Forestry Centre is located in Sault Ste. Marie and has a worldwide reputation for scientific excellence and is a world leader in forest research.The Sault Star
