The frequency severity, and extent of wildfire are strongly linked to climate. In a warming climate, we are experiencing earlier snowmelt, lower summer soil moisture and fuel moisture, more drought, and longer fires seasons. Collectively, these conditions have led to increases in fire extent and challenges for land managers.
Increasing temperatures and changes in precipitation and snowmelt patterns are increasing the severity and size of wildfires in the West, especially in the northern latitudes, including Alaska. Much of the West has experienced prolonged drought in the last decade. Florida, Georgia, Utah, California, Texas, Arizona, New Mexico, and Colorado have all experienced their largest and / or most destructive fires in history in the last six years.
These changing patterns of temperature and moisture also contribute to fire indirectly. Warmer winters increase insect populations such as mountain pine beetle. Moisture-stressed trees are also more vulnerable to insect attack. Large areas of dead and dying trees contribute to fire hazard by providing excess fuel.
The interaction of fire with stressors such as drought, insects and invasive species has the potential to cause drastic changes in structure, productivity, and carbon storage across large landscapes. In some ecosystems, this may cause long-term changes in species distribution and abundance. Places such as Alaska and the American southwest may already be seeing such impacts.
Wildfire Management in the Forest Service
Climate change and the increasing magnitude of wildfire occurrence and impact on natural resources, communities, and on our own agency require an adaptive response. In fire management, we manage fuels and vegetation to mitigate fire risks. We work collaboratively with communities to increase their resilience and preparedness for wildfire. When wildfire occurs we have a variety of response tactics. These tools line up with the goals of the Cohesive Wildland Fire Strategy: resilient landscapes, fire-adapted communities, and safe, effective, and efficient wildfire response.
The fire management community is very good at suppression -- 98% of fires are suppressed in initial attack. However, recent trends in large fires show that this success rate may not be sustainable. We're seeing more large fires, more acreage burned. On average, there were seven times as many fires / year larger that 25,000 acres in the last decade compared to 1970s.
In light of increasing trends in large fire occurrence, we need to continue and ramp up our long-term commitment to increasing both community and ecological resilience -- to increase our ability to live with fire, to create conditions where fire can visit with less than devastating outcomes. That is the goal of our fuels management program, as well as our work with partners, states, and communities. Our strategies to manage fuel are not different under a changing climate, but climate change gives urgency to our efforts. We thin dense stands to reduce moisture stress, we remove surface fuel such as litter and woody debris and small trees we call ladder fuels. We reintroduce fire to stands using prescribed fire under moderate conditions rather than waiting for a wildfire to occur. All of these strategies are cornerstones of fuel management.
Managing fuels to reduce potential fire size and severity helps us preserve the important ecological role of forests and the many benefits they provide society -- even in a warming climate.
Climate scientists warn us to expect not just increasing average temperature, but more extreme events and variability as the climate continues to warm. One of our concerns is not just an increase in fire occurrence, but fire that is outside the range of our experience, exposing firefighters, communities, and important resources such as water to increased risk.
Foresters and land managers are trained to take the long view -- our Forest Service mission is to sustain the health, diversity, and productivity of the Nation's forests and grasslands to meet the needs of present and future generations. Responding to climate change is a commitment to the future.