The politicization of the Western wildfires will not help us fight them — and will not prevent future crises. California Gov. Gavin Newsom (D) is certainly correct that they signify a “climate damn emergency” and that the question of whether global warming is occurring is settled. The wildfires burning in the West are as large, hot and fast as they are because of climate change, as more heat and less water make vegetation more flammable.

On the other hand, although President Trump’s discussion of “forest management” is politically motivated — his goal is to deny climate change and shift blame onto states — he’s right that significant mismanagement has occurred, although it has largely been on federal lands. Oregon Gov. Kate Brown (D), too, has cited “decades of mismanagement of our forests in this country.” After all, the three things you need for fire are oxygen, heat and fuel — and poor management means there’s more fuel to burn. Climate change makes it all the more important that we improve our forest management policies. 

Forest management has not affected all forests in the same way. In dry forests, such as those now aflame in California’s Sierra Nevada and coastal mountains and in eastern Oregon and Washington, there is too much fuel as a result of a century of fire suppression. Before then, these forests burned (less severely) with some regularity. Lightning started some of the blazes, which helped clear out fallen trees and dead vegetation — what ecologists call “surface fuel.” They also killed younger trees, leading to more variety in forest density; such variety can limit the size of fires. Indigenous peoples, until they were driven out, managed the forests for food and fiber by intentionally lighting fires in a practice similar to today’s prescribed burning.

When the United States started stamping out fires in dry forests to protect settlements and timber — the effort began in earnest in 1935 when the Forest Service implemented a “10 a.m.” policy, under which all identified fires were to be suppressed by 10 a.m. the next day — the surface fuel and density problems began to mount. This development fundamentally altered the way fire interacted with the vegetation: Flames could now move more easily from the forest floor into the canopy. While these “crown fires” are normal for some forests, such as the lodgepole pine forests in Yellowstone National Park, dry forest species are not adapted to this type of event. 

For years, even as the fuel built up, it remained pretty easy to put out significant fires, because the West was wetter and cooler than it is now. Beginning in the 1980s, however, as temperatures rose, the area susceptible to wildfires in the West began to spread. There were more crown fires in dry forests, and the problem grew significantly worse over the next three decades. (In some cases, like the Creek Fire, near Fresno, Calif., the surface fuel problem has been made much worse by a hot drought — exacerbated by global warming — that lasted from 2012 to 2016 and killed more than 100 million trees in the Sierra Nevada.)

If we restore variation in tree density and reduce surface fuel, we can reduce the chance that dry forests burn in raging crown fires of the sort we’re seeing this year. In some places, this means mechanically thinning the forest: People with chain saws or other specialized equipment cutting and removing small trees. In other places, the work can be done with fire: intentionally igniting the forest when weather and fuel conditions are conducive to controlled burns through the understory. Whether we start with thinning or go straight to burning, reducing large, fast-moving blazes in dry forests will require a lot more of the right kind of fire.

Embracing proper forest management also means we’ll have to change our ideas of what a forest should look like. In the Western United States, we’ve come to expect that a forest should be thick with green trees and the skies cerulean blue all the time. The fact is that in dry forests, “thick with green trees” is dangerous, and if the skies don’t periodically have small amounts of smoke from managed burns, massive fires — together with heavy smoke that darkens the sky and degrades air quality — will happen routinely.

The drivers of wildfire vary depending on the forest type, and therefore appropriate forest management varies, too. In the wetter forests of the west Cascades, in western Oregon, fires were far less frequent in the distant past: Decades or even centuries might pass between them. These forests are what ecologists call climate-limited. There is always plenty of fuel to burn, but most years it is too wet to catch fire. As a result, thinning and prescribed burning won’t change the wildfire hazard — although that doesn’t mean poor forest management hasn’t contributed to the current devastation.

On the west slopes of the Cascades, for example, plantation forestry makes fires worse. To produce inexpensive lumber for hardware stores, timber companies need to grow trees quickly and efficiently, so they plant them like crops — homogenously. While it still takes very hot and dry conditions to get these forests to burn, when extreme weather combines with homogenous fuel, flames spread faster. We need more research to understand how climate change will affect wetter forests, in particular.

Problems with excess fuel took more than a century to develop and will require several decades to resolve — if we tackle the problem aggressively. No doubt this will be an expensive endeavor, but we’re already paying billions of dollars to suppress fire and fix the damage it does. And laying the blame for poor forest management on the states (as the president does) is disingenuous, because a large portion of Western forest lands is managed by the federal government. Our national forests are among our greatest assets, and we ought to invest in managing them effectively.

It’s a false dichotomy to posit that the fires of 2020 are caused either by climate change or by poor forest management. The scientific research is clear that both play a role, even if that observation does not lend itself to a sound bite or a tweet.

Twitter: @MatthewHurteau