Climate change is increasing fire risk in Idaho

Climate doesn’t cause fire, it enables fire

Starting a wildfire requires three ingredients: Oxygen + Spark + Fuel. In the outdoors, oxygen is easy to come by. Humans and lightning can provide the spark. Trees, grasses and other flammable vegetation provide the fuel. It is the fuel that is the key to the level of intensity of a fire. The drier the fuel, the more likely fires will spread. According to researchers at the University of Idaho, climate change is affecting the dryness of forest vegetation.

The Springs FIre, Banks-Garden Valley, ID, Boise National Forest, Idaho Dept. of Lands, August, 2012

Rising temperatures are desiccating fuels earlier in the summer. Warmer springs have led to earlier snowmelt, which characteristically acts as a supplemental hydration source for plants during the growing season. This research suggests precipitation declines attributable to human-caused climate change are responsible for approximately half of the summer dryness of vegetation. Earlier drying and snow melt have extended the fire season and increases the window of opportunity for a stray cigarette butt or lightning strike to hit that landscape and start a fire.

Learn about carbon dioxide and forests in this short Forest Fast break video here.

More Fire, Less Re-Growth

Further, evidence suggests that climate change is also playing a role in forest resiliency after a major fire. Results from a recent study highlight significant decreases in tree regeneration in the 21st century. There isn’t as much precipitation as there was 30 years ago, which means unfavorable post‐fire growing conditions, significantly lower seedling densities and increased regeneration failure. Dry forests that are already stressed are prone to convert to non‐forests after wildfires. Climate‐induced reductions in forest health have important consequences for a myriad of ecosystem services now and in the future.

Weather

Natural weather can have an impact on Idaho forests too. Windstorms associated with cyclonic systems, and their cold fronts, do some damage to trees each year in Idaho. Storms of this type may occur at any time from October into July, while during the summer months strong winds almost invariably come with thunderstorms. The incidence of summer thunderstorms is greatest in mountainous areas, where lightning can cause serious forest and range fires. But most fires are not caused by lightning, rather humans cause the most fires. In 2018, 202 wildfires in Idaho were caused by humans, while just 56 were caused by lighting.