The West is on fire. More than a half dozen fires are burning across Colorado, and they are hardly worse than those in Utah and New Mexico. Colorado Springs declared an emergency situation Saturday, qualifying them for federal aid, while the Fort Collins fire expanded to more than 80,000 acres this weekend. Hundreds of homes have been destroyed already, and more seem to be set for the same fate in the near future. Conditions across the West are hot, dry and windy, and show little inclination to change.

Topography, climate and fuel are the three primary components that drive wildfires. Fires are more likely to climb steep hillsides than shallow ones, and in climates like much of the American West that are dominated by arid and semi-arid forests, the lack of moisture allows many fires to spread quickly and unpredictably. On top of all this, nearly a century of fire suppression has created crowded forests ripe for burning. With this much fuel, fires can rip through forests much hotter than they would have otherwise, thereby damaging an ecosystem designed to benefit from such events.

Firefighters recognize three types of fuels in a forest – surface, which is composed of grasses, shrubs and other low-lying plants; ladder, composed of mid-level tree branches and fallen trees that allow a fire to climb vertically; and crown, which are the highest branches of the trees that form the forest canopy. When surface and ladder fuels are allowed to build up, the possibility that a fire will leap into the canopy and combust into a major fire is greatly increased. Once in the canopy, the fires are much more difficult to manage, and generally cause greater harm than surface fires.

Prevention has become a major part of firefighting. Thinning forests is one of the most widely-used techniques, as it eliminates overgrown surface and ladder fuels. If done properly, and if the fires stay within control, natural fires through thinned forest are healthy components of the ecosystem. Trees like Ponderosa Pines have thick jackets of bark that protect them from all but the hottest fires, and some seeds even require fire in order to take root. Indeed, countless other benefits are derived from fires in natural conditions. Firebreaks are commonly implemented, as well. In these, certain key areas, often near the wildland-urban interface, are cleared of trees in order to protect structures or slow burning. This is often done on ridges or near the perimeters of towns. An oft-used but controversial tactic is controlled burning, in which fire crews will burn areas of forest in order to prevent natural fires from spreading as quickly through the same areas. These areas work as a type of firebreak during big wildfires, slowing the flames and reducing the heat. In the best of circumstances, this allows firefighters the opportunity to take control over the flames.

But the greatest knowledge comes from knowing that fires are unpredictable. They can traverse massive tracts of land in mere minutes, choking off the area for hundreds of square miles with thick smoke and ash. The fires in Southern California in the fall of 2010 sent plumes of smoke across the Pacific Ocean large enough to be seen from space. Several computer programs work to compile outrageous amounts of information about terrain, ecology, weather, human structures and countless other variables to try to predict where and how fires will burn. The sheer size of the American West and other fire-prone areas like southeast Australia means that even large controlled burns and forest thinning has little effect on the really big fires. To combat this problem, scientists have derived certain principles from wildfires that allow them to undertake the most effective fire prevention tactics possible. A 2003 study by the US Forest Service concluded that:

“Evidence from natural fire patterns that have fragmented fuels across landscapes suggests that mosaic patterns can limit the growth of large fires… Model simulations of landscape fire behavior indicate that the spatial arrangement of treatments greatly influences the amount of area that needs to be treated. Strategic placement of treatments… creates landscape fuel patterns that can be expected to slow fire growth and modify behavior while minimizing the amount of treated area required.”

But even these are no guarantee in the midst of one of nature’s most powerful forces.

Right now the West is on fire on a scale similar to the epic 2002 season, when three of Colorado’s largest fires decimated the landscape, and even forced the Hardrock 100 to cancel the race. A dry winter and abnormally warm spring has leveled against us the fury of fire in dry, hot and windy conditions. Combine this with the fact that millions more people live in the West than even twenty years ago, and the danger to humans and infrastructure is appalling. Firefighters now recognize that fire is healthy and necessary to forest ecosystems, but the number of people living in the West means more fires have to be fought to save homes, and conditions are now such that many natural fires become too big and too hot to aid the forests. Even more appalling is the dollar amounts being spent on these fires – big fires easily cost tens of millions of dollars to combat, up astronomically over the past half-century, while fires continue to increase in size and number. The cracks in our system are beginning to show.

And as I write this on my front lawn in Silverton, Colorado, on an evening cool enough for a jacket, watching the last of the day’s sunlight play against the rocky peak of the Sultan, I’m acutely aware of the danger to these mountains. In the immediate future, my favorite race may be in jeopardy, but the long-term prospect is even more fearful. These magnificent mountains are, in part, so wonderful because they are clothed in thick layers of forest that provide shelter to innumerable plants and animals that breathe life with their presence. To see these destroyed would be to lose a fundamental part of my favorite place in the world. I hope to be able to continue to enjoy the dappled sunlight of a summer morning while I run through the mountains.