Adding fuel to the fire

Hot stuff

I have written about wildfires multiple times now, which is concerning, to say the least.

Most recently, I wrote about the summer of 2023, notable for the record fires in Canada and dense smoke that clouded the eastern half of the U.S. for weeks. In that piece, I focused on the need for effective and logical landscape management and pointed out the ways in which climate change might affect wildfires.

There are no simple solutions — one question often leads to another and another and another. So I have been developing a framework to understand and manage complexity as we adapt to our changing climate. Here, I will rely on that developing framework to focus on the complexity around accumulation of heat and its influence on changing wetness and dryness.

Fire and rain

Let’s start with the one thing about climate change that is most certain: Our world is getting warmer. In the case when water is available, more extreme precipitation will occur. This is observed.

But will it get wetter or dryer? That depends on several factors. First, is it raining more? Or is it only raining harder? If it is raining more, is there a large enough increase to balance out the additional evaporation caused by the warmer temperatures? If yes, get ready to get wetter.

So, how do these wetter conditions impact the prevalence of fire?

On one level, the answer is easy: Less fire.

Therefore, one outcome of climate change would be places/time periods with less fire.

Things get more complicated when we think beyond the role of water in suppressing or eliminating fire. One of fire’s three essential ingredients is fuel, and with wildfire, that fuel tends to be trees, brush, grass, and other vegetation. A seemingly positive rainy spring may promote a burst of welcome growth. But this is potentially a burst of fuel if, subsequently, the landscape dries out and goes unmanaged. That burst of wetness in one season can be “remembered” as more fuel a few months later.

Thus we face the counter-intuitive possibility, perhaps even the likelihood, that a wet growing season could set up the ideal conditions for an active fire season, particularly when the growing period is followed by a dry summer and fall.

Dry as a bone

In cases where water is not available from seas, lakes, or swamps, a warming climate will certainly create dryer conditions, even amid rainfall. Guidance from climate models suggests dry conditions will be a recurring theme in any locale that normally experiences both wet and dry conditions over the course of year.

The increased heat will lead to drier soils and drying plants. Vegetation on the landscape will become potential fuel for wildfires. It is this increase in fuel, especially in forests and grasslands, that is expected to enhance the conditions for fire in a warming climate.

Another way a warming climate can affect the availability of fuel is its impact on tree-killing pests. Notably in the western parts of North America, pine beetles have killed many millions of trees. Because of the warmer temperatures, fewer beetles are dying in the winter. In some cases, they have an extra life cycle in the warm season.

Fire is natural

Throughout human history, we have learned to suppress and manage fire, even to the point of believing we can eliminate fire. However, this has proved not to be the case because it is impossible to eliminate all sources of ignition. (There is always lightning.)

It actually is reasonable to think of fire as a type of weather, similar to a storm. Then we can ask, how will a warming climate influence fire?  Since we already experience many types of fires, we should expect that trend to continue. We may see big forest fires, grassland fires, and smoldering peat fires. We may have a large number of small fires and we may have record-breaking large fires. Perhaps most likely, we should expect wildfires in places and during seasons when they have been historically uncommon.

Chatter and controversy often follow the ways in which fires are reported in the press — headlines cry out that large fires are being caused by climate change. Sweeping statements about global wildfire trends are common among experts and non-experts alike. But as with other aspects of climate change, there is no one outcome, no one thing that climate change will do.

Fire walk with me

If we think about what I’ve written here, we would expect a future in which some regions will experience more fires, while others will have fewer fires. Therefore, combining fire measures into a global average obscures the story in important ways. It is certainly meaningless for planning in a region that experiences long wet and dry seasons.

If we focus on regions with drying vegetation, the Sierra Nevada of California, for example, then there are huge changes in the character of fires. The season is longer, and has featured many recent fires of record extent and duration. The same is true in Canada.

With warming temperatures in the eastern part of North America, planners also need to consider increased fire risk. Onset, intensity, and persistence of drought will likely increase. In other words, when there is drought, the drought is likely to be more extreme. I have found the First Street Foundation has developed a credible tool for thinking about fire risk.

Also, as with many of the consequences of climate change, there is a strong dependence on what the conditions are on Earth’s surface, including how we have chosen to manage the landscape. Surface landscape is so instrumental to the science of climate change; it is essential to include it when developing planning scenarios to help us adapt to our changing world.

In my next column, I will discuss the importance of including surface conditions in climate planning.

(Lead image: iStock.)


  1. David Carlyon - 1971

    Prof. Rood,

    I’m wondering your parenthetical reference to lightning. You seem to suggest that it is a minor cause of forest fires.

    However, fighting forest fires in the West (to put myself through Michigan), I was told that lightning was the major cause of fires, followed by loggers, and only then, regardless of what Smokey Bear said, careless campers.


    P.S. When not on fires, I also played Smokey at ranger station campfire programs at Diamond Lake, Oregon.


    • Richard Rood

      Hi, I did not mean to suggest lightning was small, only that it was outside of our control.

      As I recall, a recent paper said about 40% of fires were caused by lightning. That in very remote areas it was near 100% and many of the largest fires were started by lightning.

      I have seen several papers that suggest arson, things that happen next to highways, and down power wires in wind storms are all significant if not near the top … perhaps regionally?

      Here in Colorado when we go into fire mode aside from open fires, outdoor shooting is prohibited.

      thanks for the comment.



  2. Jonathan Blanton - 1975

    Forest and other flora and vegetation management is the most important and effective way to prevent destructive wildfires, regardless of the vagaries of climate change, which are and will always be with us. But these sensible and necessary actions have not been properly and thoroughly taken for decades due to irrational policies and political considerations.
    Also property insurance for wildfires risk should be appropriately expensive for those who choose to build or live in high risk areas, or not available at all if deemed too risky by objective standards. Likewise, public and government and taxpayer funds should not be available to bailout or backstop those who choose not to purchase insurance.


    • Richard Rood

      in a fundamental way I agree with you. The point of an earlier article was that fuel management was our best lever. A warming climate should motivate us to do the things we know will work more diligently.

      As for property insurance, ours has gone up a lot since the Marshall Colorado fire and we are not in what is considered a historical fire district.

      The more I read and observe, the more important it seems to perhaps do much better management around power lines, and perhaps make the practice of burying or containing them more routine.

      thanks for your comment


  3. Alvin Bey - 1960 MS in Chemistry

    Dr. Rood: I enjoyed your articles and particularly appreciate the breadth of thinking you apply (as differentiated from our US government) to the global climate issues in the world. As I read your articles I also wondered about another factor that has received less attention; i.e. the the work of Dr. Walter Jehne of Australia. He has lectured widely around the work and suggest a potential solution via the impact of the greatly increased carbon content of soils and the inherent hydrological factors that lead to cooling. Lot os U-tube talks are worth listening to. Perhaps, the ‘regenerative agriculture’ movement in the USA , with increased carbon and soil water content, could someday help in climate moderation. Keep up the good work.
    Alvin Bey – University of Michigan – 1960 MS Chemistry, retried industrial scientist


  4. Dave Brewster - 1978

    Living in Summit County, CO, high in the mountains where the influx of tourists may be as high as anywhere in the country, I can say that most of our wildfires are human caused. I am told we have over 10 million visitors to the White River National Forest each year. We average almost one significant wildfire per year in the county and in the last four or five years all the fires are or are suspected to be human caused. In both Colorado and California humans cause almost all the fires through a wide variety of methods: powerlines in high winds, flat tires with rims on the pavement showering the road shoulders with sparks, the “campers” (sometimes indigent squatters) campfires, the casual cigarette butt which I regularly clean off my property, …. In a few years, we may ban outside fires in the county during the summer, but I fear that will only help slightly. While I strongly support buffer zones around our neighborhoods, I question clearcutting miles from infrastructure. Two hundred years ago our forests were dominated by moist fir and spruce. Thanks to lumbering and fires during mining 150-100 years ago, today they are dominated by fire encouraging lodgepole pines. Clear cutting prevents natural succession and the return of more fire-resistant fir and spruce. Some wonder if climate change would prevent spruce and fir from returning, but I am an optimist.


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