In 2015, American forests were ravaged by larger and more destructive fires than ever before. One of the most devastating wildfires occurred in Washington State and burned over 250,000 acres of forest at a rate of 3.8 acres per second.1 These unprecedented grand burns of over 100,000 acres have been justifiably coined by researchers as “Megafires.”2 Unfortunately, megafires are becoming an increasingly common feature of the American West.
Although forest fires are a natural and essential part of a forest’s life cycle, scientific records show a worrisome trend. Data from the National Climate Center in Asheville, North Carolina indicate that recent fires burn twice the forest acreage as wildfires 40 years ago.3 In contrast to replenishing wildfires that promote forest growth, megafires scorch the landscape, disabling forest regeneration and leaving wastelands in their wake.2 In other words, they burn forests so completely that trees are unable to regrow.4 The increased incidence of megafires accordingly threatens to cause environmental change, particularly in the Western United States.5 Once-rich forests are now in danger of depletion and extinction as they give way to grasslands and shrubs. Even the hardy Ponderosa Pine, previously thought to be completely flameproof, is succumbing to megafires.5
What is the future of our forests, and what can we, as custodians of our natural lands, do to shape this future? Can we prevent megafires? Understanding the contributing causes of megafires is essential in devising a solution to prevent them. Current thinking by various ecologists identifies three primary causative factors, both behavioral and environmental: new firefighting strategies, the rise of invasive species, and climate change.1
Government policies that promote aggressive control of forest fires are deceptive in their benefits. Fire-fighters have become incredibly efficient at locating and extinguishing wildfires before they become too destructive. However, certain tree species that have flame- and temperature-resistant properties, such as the Pine Barrens, Lodgepole Pine, and Eucalyptus, require periodic fires in order to reproduce.6 When facing wildfires these types of trees survive, whereas other plant species perish. Since flame-resistant tree species are often native flora to forest ecosystems, the selective survival of these trees maintains the forest’s composition over time and prevents shrubs and grasslands from overrunning the ecosystem. Flame-resistant trees accomplish their phoenix-like regeneration and self-sustainability by releasing their seedlings during a wildfire. In addition, forest fires destroy flora that would impede the growth of new seedlings through competition for space and light. This regenerative effect of forest fires has even resulted in the return of certain endangered tree species.4 One example, the Jack Pine, maintains its seedlings in cones that melt in the presence of fire. A policy to extinguish fires prematurely can inhibit seed release, threatening Jack Pine forests and others like it.6 To date, aggressive government policies toward forest fire-fighting have led to significant changes in forest composition accompanied by buildup of tinder and debris on the forest floor. This accumulated undergrowth now fuels megafires that burn with unparalleled intensity and speed. In contrast, forest management policies that revert to the practice of allowing small, controlled fires to clear away debris would maintain the forest’s long-term survival.
Invasive, flame-susceptible species provide the perfect fuel for megafires. During their westward expansion in the 1880s, settlers were not the only ones to achieve Manifest Destiny. Several species of grass also made the journey. The most common of these species was the Cheatgrass, a grass native to Europe, southwestern Asia, and northern Africa.7 Cheatgrass was inadvertently brought to the Americas on cargo ships in the 1800s and has been a significant environmental problem ever since. The short life cycle and prolific seed production of Cheatgrass causes it to dry out by mid-June, meaning that it serves as kindling for fires during the summer. Cheatgrass increases the size and severity of fires since it burns twice as much as the endogenous vegetation.7 Since the native vegetation is slowly being choked out by Cheatgrass, the landscape of the American West is transitioning into a lawn of this invasive species, poised to erupt into an inferno.
Global warming, one of the environmental causes of megafires, is perhaps an even more critical and challenging threat than invasive species. In 2015, forest fires ravaged more than 9 million acres of the Western mainland United States and Alaska.3 Studies of global warming demonstrate that every degree Celsius of atmospheric warming is accompanied by a four-fold increase in the area of forest destruction. Thus, the increase in global temperature is directly associated with the prevalence of megafires.8 Since the 1900s, the average temperature of the planet has increased by 0.6 degrees Celsius, primarily in the twenty-first century.9 Typically, severe fires burn less often at higher altitudes, due to cooler temperature and greater moisture levels, but as global temperatures increase, these areas become drier and more prone to forest fires. This warming of the climate contributes to massive burns that are fueled by centuries of forest debris and undergrowth.9 Climate change also contributes to a lack of precipitation, which further contributes to the expansion and intensity of forest fires. Wildfires themselves also contribute to climate change; as they continue to burn they emit greenhouse gases, which can contribute to accelerating global warming.9
Ultimately, due to poor policy practice, a destructive cycle is forming that serves as a catalyst to megafires. Finding long-term solutions that will prevent the occurrence of megafires will require policy adjustments at the regional, national, and international levels.6 Currently policies are changing, endorsing smaller burns to limit build up for megafire fuel. As more data is being introduced about global warming, efforts are being made to find more renewable forms of energy such as solar and wind.9 Ideally, this shift in resources will limit the increase in global temperatures and reduce the risk of megafires. Lastly research is being done to develop grasses that can out compete the problematic Cheatgrass.7 If we can meet these challenges, then megafires may finally be extinguished.
- Why we have such large wildfires this summer. http://www.seattletimes.com/seattle-news/northwest/why-we-have-such-damaging-wildfires-this-summer/ (accessed Oct. 9, 2015).
- National Geographic: How Megafires Are Remaking American Forests. http://news.nationalgeographic.com/2015/08/150809-wildfires-forest-fires-climate-change-science/ (accessed Oct. 11, 2015)
- Climate Central: The Age of Western Wildfires. http://www.climatecentral.org/news/report-the-age-of-western-wildfires-14873 (accessed Oct. 9, 2015)
- Deadly forest fire leads to resurrection of endangered tree. http://blogs.scientificamerican.com/extinction-countdown/deadly-forest-fire-leads-to-resurrection-of-endangered-tree/ (accessed Oct. 9, 2015)
- Rasker, thesolutionsjournal 2015, 55-62.
- NPR: Why Forest-Killing Megafires Are The New Normal. http://www.npr.org/2012/08/23/159373770/the-new-normal-for-wildfires-forest-killing-megablazes (accessed Oct. 11, 2015)
- Keeley, International Journal of Wildland Fire, 2007, 16, 96–106
- Stephens, Frontiers in Ecology and the Environment 2014, 12, 115-122.
- Climate Central: Study Ties Warming Temps to Uptick in Huge Wildfires. http://www.climatecentral.org/news/warming-huge-wildfire-outbreaks-19521 (accessed Oct. 21, 2015)