A new post at WUWT claims to “debunk” claims that “human caused warming doubled western U.S. area burned since 1984.” It was in response to a story in the LA Times of new research in PNAS (Publications of the National Academy of Science).
The LA Times article, like the PNAS research, is about area burned in the western continental U.S. But the WUWT post includes some bizarre statements, such as this:
The new study considered two time periods for comparing burned area acres and those were from 1984-1999 and from 2000-2015.
The number of U.S. wildfires for the period 1984 to 1999 is essentially unchanged from the number of U.S. wildfires for the period 2000 –2015.
Since the research is about area burned, why are they talking about number of wildfires?
It’s easy to figure out why: because if you look at number of fires there’s no real difference between the two time spans, but if you look at area burned the difference is obvious:
Attempting to “debunk” an increase in area burned by pointing to number of wildfires, is a classic example of changing the subject. It’s one of the most pervasive of all denier techniques.
The WUWT article goes on to say:
Additionally the latest year to date wildfire data (http://www.nifc.gov/fireInfo/nfn.htm) for the last ten years shows absolutely no consistent upward trend whatsoever in either burned acres or number of U.S. wildfires which have occurred.
This is even more bizarre; the WUWT article points out that they compare the 1984-1999 time span to the 2000-2015 interval, but now they want to talk about the lack of trend in year-to-date values only, using the 2006-2016 span only? That’s only 11 years’ worth, which will inflate the uncertainty in a trend estimate immensely. Of course, there’s no actual analysis here so there’s no mention of how uncertain trend estimates are.
Using full-year figures for 2006-2015 the estimated trend is negative, at -165000 acres per year. But it’s not statistically significant (no surprise, since there’s only 11 years’ data); the uncertainty level (95% confidence) is +/- 629000 acres/yr.
In fact the whole idea of trend-analyzing a mere 11 years in isolation not only relies on a ridiculously small amount of data, it also ignores what came before their chosen starting point. It’s tantamount to using a “broken” trend, one in which what happened before 2006 isn’t allowed to inform what the trend really is. The model is therefore like the blue line shown here:
It makes no sense to call that the “trend,” unless you want to ignore what happened beforehand because it tells a different story.
We can even compute the uncertainty in the trend model for both time intervals and add them to the graph as dashed lines, here:
When the uncertainty range (shown by the dashed lines) is included, we can see that a single, unbroken trend using the entire span 1984-2015 is perfectly consistent, not just with the whole interval, but with the analysis of the separate intervals:
Criticizing a comparison of 1984-1999 to 2000-2015 by discussing a tremendously uncertain trend estimate using only data since 2006, they’re once again indulging in the beloved denier practice of changing the subject. Because, after all, they can’t deal with the subject.
But wait, there’s more! They add this:
The new wildfire study also fails to address that U.S. drought data does not support claims of increased nationwide droughts as driving increased number of wildfires.
It’s about wildfire, not drought … the funny thing (hilarious, actually) is that neither the LA Times article nor the abstract of the PNAS research mentions the word “drought.” Which makes it yet another case of changing the subject by those who can’t deal with the subject.
And by the way, where are the claims of “nationwide” droughts, or even “nationwide” anything, in the articles they’re attempting to “debunk.” It’s all about the western continental U.S., so including the entire 48 states means that regions with decreasing drought (in the eastern U.S.) cancel out regions with increasing drought (western U.S.). And that’s why the WUWT article does so: to cancel out drought increase in western U.S. regions by including regions the article is not about.
It turns out that U.S. drought data does support claims of increased drought in the west and southwest:
The whole post is an immense bait-and-switch. The subject was supposed to be area burned by wildfire in the western U.S., comparing the 1984-1999 time span to 2000-2015. Instead, we’re “treated” to misdirection about number of fires, a “trend” ignoring everything before 2006, and drought (not the subject) which has to ignore the “western” part of “western U.S.” to avoid giving away the game.
I guess they just can’t deal with the subject.
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