In 2005, a group of fire experts announced the onset of a catastrophic new age: the era of the mega-fire. In a concept paper, “The Mega-Fire Phenomenon,” published by the Brookings Institution, federal wildland firefighting officials defined these mega-fires, which burn more than 100,000 acres, as “extraordinary, in terms of their size, complexity and resistance to control.”

Once rare, these conflagrations are now the norm. Colorado has experienced several mega-fires over the past 15 years In 2013, the West Fork fire scorched more than 110,000 acres near Wolf Creek Pass. In 2002 the Hayman fire, the state’s largest, killed five firefighters, destroyed more than 100 homes and devastated nearly 138,000 acres.

Mega-fires are consuming Western states. A 256,000-acre fire hit Washington in 2014, followed in 2015 by blazes of 218,000 acres and 145,00 acres. The Murphy Complex fires burned 652,000 acres in Idaho in 2007. Oregon’s Long Draw fire in 2012 scorched 557,000 acres. Alaska is the epicenter of the mega-fire phenomenon, suffering through fires of 1.3 million acres (2004), 636,000 acres (2009) and 615,000 acres (2004) in recent years. Canada’s forests are also ablaze. Last year, the Fort McMurray fire burned 1.5 million acres, forced the evacuation of thousands, and was declared one of Canada’s worst natural disasters ever.

A record 10.1 million acres burned nationwide in 2015. “The U.S. burns twice as many acres as three decades ago,” and that acreage “may double again by mid-century,” states the 2015 United States Forest Service report, “The Rising Cost of Wildfire Operations.” The six worst fire seasons since 1960 have come in the past two decades, and “many western states have experienced the largest wildfires in their state’s history since 2000.”

The forests of the West are undergoing climactic change. Colossal beetle kills. Mega-fires and more acreage aflame. Simply put, we are witnessing the slow-motion collapse of an ecosystem. Our forests are dying.

Global warming is the big culprit. It’s two degrees Fahrenheit hotter now in Colorado than it was in the 1970s. Hotter temperatures and earlier snowmelt have lengthened the fire season by 78 days since 1970, according to some studies, and the fire season now lasts 300 days per year in some regions of the country. A 2016 study by the Lamont-Doherty Earth Observatory at Columbia University says hotter temperatures and shorter winters have doubled the amount of acreage burned since 1984. Doubled.

Science tells us it will only get worse. Some climate models predict temperatures could rise 6.5 degrees in Colorado by 2050. If that happens, the forests of Colorado as we know them will be gone. Common Colorado tree species will be in decline, replaced by sagebrush, grasses and shrubs, and aggressive invasive species such as cheatgrass.

A reckoning is coming—about where we live, how we protect our communities, how we adapt to flames. Coloradans’ relationship to fire will become even more intimate.

A History of Fire

Fire has always been part of Western forests. Prior to European settlement, lightning was the prime ignition source. Now humans, through carelessness or arson, provide the spark. A 2017 study in the Proceedings of the National Academy of Sciences examined 21 years of wildfire data and determined that humans, deliberately and accidentally, started 84 percent of wildfires during that time. More people living in and visiting Western forests means more cigarette butts tossed from car windows, more campfire embers, more sparks from dirt bike tailpipes.

Smokey Bear, though well intentioned, deserves blame. A century of all-out fire suppression has left many forests choked with fuels and dry tinder. Paul Bunyan is another culprit. The turn-of-the-century timber barons who clear cut mountainsides and decimated old-growth forests forever altered ecosystems that had evolved with flame.

Now we are paying the price. Prior to 2000, the federal firefighting bill never topped $1 billion. Since then, the tab has topped that amount 13 times. In 2015, the federal cost for fighting wildfires hit a record $2.1 billion. Last year it was nearly $2 billion. Firefighting now eats more than half of the U.S. Forest Service budget. By 2025, the figure could be nearly 70 percent, according to agency estimates. In 1995, firefighting was just 16 percent of the agency budget.

This should alarm recreationalists, wildlife watchers, hunters, anglers and others who value national forests. Wildfire is bleeding the Forest Service of money for other important programs—recreation and trails, wildlife management, habitat restoration and more.

Future Forests

What will future forests look like? The grasslands of Boulder County’s Walker Ranch open space provide a glimpse of the impacts of fire and global warming. In 2000, the Walker Ranch Fire consumed 1,100 acres of ponderosa pine forestlands. Historically, low-severity fires burned through ponderosa forests, clearing out brush and creating an open and park-like ecosystem of tall trees with grassy spaces between that supported a diversity of plants and wildlife. When old ponderosas died, new seedlings took root. No more.

Seventeen years after the Walker Ranch Fire, the ponderosa pines are not growing back. The forest is receding, the grasslands advancing. “In most parts of the Walker Ranch burn area we are not seeing any considerable number of seedlings regenerating,” says Thomas Veblen, a University of Colorado geography professor. Veblen has studied Colorado’s Front Range forests since the early 1980s, and he has seen this pattern repeated at many burn sites. “At the drier, lower elevations, there is frequently no tree regeneration.”

Research from elsewhere in the West shows the same thing: Forests are disappearing on their southern fringes and at lower elevations. Scientists from the University of California, Davis and the U.S. Forest Service studied burned areas across 10 national forests in California and discovered that fires have killed so many mature, cone-producing trees that the trees are not re-seeding.

“We are seeing a shrinkage of the total forest area,” says Veblen, who’s studied the growth patterns of 6,000 trees on Niwot Ridge for three decades. “When we compare mortality rates from the early 1980s to the early 1990s, and from the 1990s to now, we can see there has been a two-fold increase in the rate of tree deaths.” One of Veblen’s graduate students is working on a study whose data shows that Colorado is experiencing fewer and fewer years of successful tree establishment.

“These are some disturbing trends,” says Adam McCurdy, forest program director for the Aspen Center for Environmental Studies, or ACES. “Wildfires, sudden aspen decline, mountain pine beetle and spruce bark beetle outbreaks, these are all natural occurrences but they are becoming more pervasive.” ACES hopes to educate the public and policymakers about forest health through its Forest Forecast initiative. Forestforecasts.org is an online program that shows how various tree species will decline statewide in coming decades. The model shows that by 2050, Aspen, Colorado, will have a “low suitability” classification for aspen trees, and by 2090 the city may be completely unsuitable for them. “As educators, we are trying to communicate a slow onset disaster,” McMurdy says. “The data is sobering.”

Colorado’s forestlands will not disappear overnight, but they’re on a downward slope. We are bearing witness to the onset of the Anthropocene—total human domination of the planet’s ecosystems. Humans have become the asteroid.

Our Changing Relationship to Fire

Colorado has 24.4 million acres of forestlands, from low-elevation ponderosa foothills to dense and snowy subalpine lodgepole pine and spruce-fir forests. Colorado’s forested mountains are the water towers of the West. They protect watersheds by stabilizing soils and minimizing erosion and runoff. They sequester carbon. They are the epicenter of the state’s recreation economy. Colorado forests are home.

About two million people live in Colorado’s “wildland urban interface,” the burn zone where subdivisions meet forests. In 2000, that figure was less than a million. Like coastal residents facing rising seas, mountain communities must prepare for rising flames.

“Our old tools are not going to make it in the new era of Western wildfires,” says Tania Schoennagel, a fire ecologist and research scientist at the University of Colorado. In early 2017, Schoennagel was lead author on a study published with wildfire experts from across the West titled “Adapt to Wildfire in Western North American Forests, as Climate Changes.” The study says that fire suppression, forest thinning and prescribed burns are necessary but inadequate. The amount of acreage that needs treatment is massive.

“How do we create communities that are more adapted to fire? That is the question,” Schoennagel says. It’s a question worthy of a national debate that is not taking place. “We need to embrace and prepare for change,” adds Schoennagel, “because change is coming.”

Paul Tolme is a former Coloradan now living in the soggy bottoms of the Pacific Northwest. He is a longtime outdoors and environmental writer whose work frequently appears in SKI, National Wildlife and other publications.