More forest fire statistics, less climate change blame

Further to what I blogged about this morning, another article from MacLean’s also suggested that the number of forest fires is increasing with time. The author writes, “In the 1970s, the Canadian National Forest Fire Database tracked about 4,000 fires annually. Over the last decade it’s been over 8,000 on average.”

But a funny thing happens when you click on the link the author provides, and do a little digging into those number…

The link brings you to a page with the following chart which considers the entire nation of Canada. The data I looked at was strictly limited to Alberta.

wildfire_stats_01

As the author describes, the CNFDB did, indeed, track about 4,000 fires per year back in the 1970s, and, sure enough, it does track around 8,000 per year in more recent years.

But, wait… what’s that link above the chart? It says something about “statistics from the CNFDB compared with the NFD.” What’s that all about?

wildfire_stats_02

Holy cow! While the CNFDB was only tracking 4,000 fires per year back in the 1970’s, the NFD was tracking closer to 9,000 fires per year back then. More than double!

How do we explain the discrepancy? One of two scenarios seems likely. Either there were actually only about 4,000 fires per year, and somebody somehow miscounted by 5,000 fires, or there were actually about 9,000 fires per year, and somebody somehow miscounted by 5,000 fires. Different accounting systems between different agencies would not be surprising, and that would not be a sign of some kind of conspiracy to hide the real data, or sloppy research or anything like that. Maybe one of the agencies only considered fires that reached a certain size or something, and changed their criteria with time. Please don’t misconstrue this as a criticism of either of those agencies.

But this additional data – that the MacLean’s author didn’t take into account in his article – sheds an entirely different light on the subject. According to the CNFDB the number of forest fires has increased, overall, since the 1970’s (and it has apparently leveled off since about 1988). According to the NFD is has remained relatively steady, or slightly declined from about 9,000 per year to about 7,000 per year.

If it were up to me, I’d take the larger number from both of those data sets and assume that’s closest to reality. If we do that, then the NFD has higher numbers from about 1970 to about 1986, so we use their data. From 1986 until about 2005 the two agencies recorded very similar results. After 2005 it appears the CNFDB has reported more forest fires, so we use their data. With this modified data set, however, the trend is…

Wait for it…

Steady. Unchanging. More or less flat. Kind of like what I described in my original article. If climate change is contributing to increased wildfires, then apparently the climate hasn’t changed much in the past half century or so. Or it has changed, but isn’t actually impacting extreme weather as many people believe it is.

If you look at total hectares that got burned there does appear to be a slight increase in the average number of hectares that get burned after about the year 2,000, but the years with the largest spikes are generally from before 2,000. The top five years, for instance, are clearly pre-2,000. Total burned area is far more chaotic than the total number of fires, so trends are harder to discern; that data is ambiguous.

It would be interesting to dig through data going back even further in history, but I haven’t the time or interest to do so. This data (and what I previously examined) seems pretty clear. While the author at MacLean’s is concerned that “the horror of forest fires is roaring back” it would seem the roaring has actually remained pretty steady for a very long time. At least as long as he’s been around.

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