The Mysterious Wildfire Chart

Yet another piece of bad news is that wildfires are on the increase in the USA. I linked to that story in a blog post about extreme severe events and climate. The article was by Deanna Conners by at earthsky.org .

She offers this graphic, along with a claim that 2015 was (as of mid-September) already in the top six wildfire years, along with the reasonable speculation that 2015 may exceed prior years:

wildfires-acresburned

These data trace to “the National Interagency Fire Center in Boise, Idaho, [which] publishes a ton of useful statistics on wildfires that are critical for helping state and federal agencies manage the flames. These records date back to the 1960s.” according to Dr. Conners’ posting.

It’s suggestive of an increase. and compellingly so after adding 2015 to the series as a top-five year.

I also pointed to an odd bit of counter-evidence that I’ve seen trumpeted triumphantly by the occasional climate troll. Unfortunately it is on a legitimate US Forest Service webpage.

tot-ac-burNow everybody who has any intuition about environmental data who has looked at this says it doesn’t pass the smell test – it looks very much as if the pre-1960 data which NIFC does not report is of something else than what NIFC reports after 1960. Unfortunately the sourcing of the graph is unclear.

In a recent comment here, Dr. Conners reports that she has worked on tracking the graph down independently. I think it’s at least important enough to quote in full in a top level article here.

Thanks for linking to my blog on wildfires. I spent some time tracking down the original source for the pre-1960 wildfire data that you linked to in the footnote of your blog—the original source for the U.S. Forest Service graph was “America’s Renewable Resources: Historical Trends and Current Challenges,” which was published in 1991 by the non-profit organization Resources for the Future. The original graph is located on page 117 of Chapter 3, and the author (R. A. Sedjo) cites “U.S. Department of Agriculture, Forest Service, 1926–1967, Forest Fire Statistics, various annual issues,” as their data source. The author also cites “U.S. Department of Agriculture, Forest Service, 1968–1989, Wildfire Statistics, annual issues,” as their data source for post-1960 data. Unfortunately, the text of that document did not describe the data in detail.

I did find a useful supplemental document (http://www.fs.fed.us/research/sustain/docs/national-reports/2003/data/documents/Indicator%2015/Indicator%2015.pdf) to the more recent U.S. Forest Service reports/graphs that had this to say about the pre-1960 data (page 19):

“Between 1930 and 1950, in excess of 10 million acres were burned by wildfires annually. Most of the area burned during this period was in the Southeastern United States (South RPA Region) and were primarily incendiary fires. Since 1960, between 2 and 5 million acres were burned annually by wildfires. In recent years, the average area burned has increased, especially in the Rocky Mountain and Pacific RPA Regions. A peak fire year occurred in 1988 when 7.4 million acres burned. This was the year of the extensive fires in the Greater Yellowstone Basin. The range of recent variation (since 1960), in terms of area burned, was exceeded in 2000 when wildfires burned more than 8.4 million acres. This was the largest area burned in more than 40 years.”

So it appears that much of the pre-1960 data were related to incendiary forest fires (per http://www.interfire.org/features/wildfires.asp, an incendiary fire is one that is set intentionally) and not to true wildfires. The post-1960 dataset that I analyzed only contained data for wildfires; the National Interagency Fire Center explicitly separates the wildfire data from the prescribed fire data. Hence, comparisons to earlier data may indeed be akin to comparing apples to oranges, as Magma cautioned earlier in their comment.

So the case isn’t exactly proven in terms of which are the apples and which the oranges, but it’s pretty compelling that it is a graph, so to speak,  of apples after 1960 and some other fruit or fruits before 1960.   Fortunately, the title of the graph is honest enough. It says “Total acreage burned – all lands” which pretty clearly indicates that it isn’t really a graph of wildfires.

I think that it does match the 1960-2006 NIFC data closely. If so it must be a plot of at least two separate and distinct records. If that in turn is so, how such a shabby thing gets on a federal website and how to get it off is another story, but examined closely, it neither supports nor refutes the claim that current wildfire extent was greatly exceeded or even precedented in the past.

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6 Responses to The Mysterious Wildfire Chart

  1. Looking at the first graph, for wildfires, by eye it would appear that some sort of tipping point occurred around 2000. Does the annual total acreage burnt by wildfire correlate to temperature, precipitation or both (or anything else)? Are there further tipping points in the pipeline? Is there a statistician out there who can perform an appropriate analysis?

  2. Magma says:

    Several weeks ago I discussed the dubious nature of the older forest fire statistics, pointed to a contemporaneous source of the compiled data used by the USFS and suggested a few possible reasons for the discrepencies here (third comment from the top):

    https://andthentheresphysics.wordpress.com/2015/10/12/show-me-slowly-what-i-only-know-the-limits-of/

  3. izen says:

    In any discussion with a motivated rejectionist of the mainstream narrative that climate change is causing more wildfires, you will be told that the cause of the increased wildfires is the stupid Greens trying to prevent the ‘Natural’ fires that always occurred before.
    All that 1960s ‘Smokey the Bear’ fire prevention and fire watch towers to prevent and control ANY fires has resulted in an unnaturally low level of fire, which is now causing bigger and worse fires because of the unnatural level of fuel that has built up in the artificially controlled forests.

    There is an element of truth in this.
    Although the efforts put into fire prevention were as much about protecting a valuable resource. Analysis of fire patterns in the 50s-60s was concerned with the amount of sawtimber or industrial lumber that an area could provide as much as preserving a supposed untouched wilderness.

    Indigenous fire-setting as a means of land-management along with a natural rate of fire had shaped the forest ecology before European settlement. The attempt to control and limit forest fires in the 60s~ was partly a misguided attempt to ‘preserve Nature’, but was also a response to a real increase in forest fire rates from agricultural settlement, mining and railroads. The lumber industry also had a role in wanting to protect a commercial crop from the increasing population and industry that was intentionally, and accidentally using fire to remove forests.

    As always the reality is complex, contingent and conditional. The ‘Mysterious Wildfire chart’ may represent a real measure of the amount of forest fire in the past. While the peak in the past may be inconvenient for a simple narrative that forest fires are increasing now because of climate change making things hotter and drier, it does represent the POSSIBLE area that could burn in the past. Both as a ‘Natural’ process and increased by the ingress of people and industry. You cannot start large forest fires unless the conditions are conducive to their occurrence. That high peak of incendiary fire was a result of low prevention and control with increased fire sources. It was also during a local climate state that had similar droughts and temperatures to the present.

    It may represent the lower range of possible fire rates given the present climate and without the modern prevention and control of fire. Which now includes controlled burning of under canopy fuel load as part of that recent increase. As any keen denialist will tell you.

  4. Eli Rabett says:

    The answer is the New Deal done it

  5. opluso says:

    It’s difficult to discuss wildfires without acknowledging the change in US forests over three centuries. Mature, climax forests are less susceptible to major fire damage and they don’t really exist today. Starting with Colonial settlement and accelerating during Post-Civil War timber “harvesting” (aka, strip-mining), natural tree cover was removed across the eastern United States. By the early 1900s the process made its way to the West Coast — “Georgia-Pacific” was not a randomly generated name.

    So along with fire suppression management you must consider that the forests themselves have changed drastically. And we are still learning to deal with it.

    As an aside, I toured Yellowstone in the aftermath of the “Great Yellowstone” fires mentioned above. Managers there admitted that suppression techniques over the decades had allowed fuel to accumulate to the point that hotter-than-natural fires sterilized the soil. Even the recovery periods and processes are changed by “modern” forests.

    Intensity, frequency and area burned all change when you change the forest itself. Like all of nature, it’s complicated.

  6. Chris says:

    A couple more factors in the up tick in acres burned could be attributed to fire management policy. Managing fire for resource benefit and no or limited suppression areas can increase totals. For example, Alaska Fire Service (aka. Bureau of Land Management) has large areas where suppression action is not taken. You can easily have a million acre fire, doing good things, but also bumping up the statistics because it’s a wildfire.

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