Introduction:
Long ago, in a debate about the relative merits and faults of Ronald Reagan (which also happened to be a hijack of this thread), I made the mistake of trotting out the old saw that Reagan had once claimed “trees pollute more than heavy industry,” as evidence of his creeping dotage. Sam Stone responded:
After providing an rather irrelevant link to support this claim, he continued:*
Clearly, here, Sam is arguing that the Smoky Mountains derive their name from the pollution produced by all the trees. I found this claim ludicrous, and said as much. When I explained why, however, Sam failed to respond to my counter-argument, and the issue was dropped.
I have avoided bringing up this embarrassment since then, out of a sense of decorum, but in this thread, I found myself so provoked by one of Conan the Canadian’s posts that I couldn’t resist reminding readers that the opinions so expressed were those of a person who also believes that the Smokies got their name from the pollution produced by the trees. To my amazement, not only did Sam continue to defend his claim, but others jumped in to support him.
Despite the fact that there are much more important events occurring in the world, and significantly more important topics for debate, I find that I simply cannot let this question go. It irks me. It is important in part because Sam’s claims are terribly misleading, but also because it provides a textbook example of how scientific findings can be misconstrued to support a given political agenda – or, as seen in this specific case, can be misused to revise the historical record, by reconstructing a historical figure – Ronald Reagan – and transforming him, as it were, from the boob he truly was into a kind of “Renaissance Man of Science.”
But let us start at the beginning. These are the specific statements made by Reagan on this question:
As I pointed out in the previous discussion on this issue, linked above, “80% of the world’s pollution coming from plants and trees would mean, if my math is correct, that 20% of the world’s pollution resulted from industry (and cars);” that is to say, Reagan is claiming above that trees pollute more than heavy industry, precisely as I had originally posited, and not that “some trees pollute,” as Sam would have the reader believe.
Nevertheless it turns out, ironically, that there was a grain of truth to Reagan’s claims. The culprit of the story is isoprene, a hydrocarbon that is also primary ingredient in the set of chemical reactions that lead to the creation of smog. Many species of trees release isoprene – one of a group of substances known as terapenes – sometimes in large quantities. In combination with man-made nitrogen oxide (from car exhaust), isoprene can form alkyl nitrate; and alkyl nitrate, when exposed to sunlight, turns into “photochemical smog.” Hence, in a roundabout sort of way, one can claim that some trees (particularly in urban forests), in combination with man-made sources of NO, contribute to the creation of urban smog. (It was later discovered that in some instances, terapenes reacted with sunlight to create so-called “fine particles” even without the intervention of man-made NOs). On the other hand, I submit that Reagan’s claims, quoted above, are hopeless simplifications of these findings, and seriously misleading as well. Reagan used this simplification, for example, to argue against anti-pollution regulations.
This is the crux of the matter. I beg the reader to keep in mind that isoprene, taken on its own, is not a pollutant. 80% of the isoprene produced by trees is oxidized into CO[sub]2[/sub]; the remaining 20% is converted into so-called “fine particles” (particles with a diameter of less than 2.5 micro-meters) of organic carbon. These particles provide the nuclei for rain, and contribute to the earth’s albedo (i.e., reflectivity). Depending on one’s definition, I suppose these products might also arguably fill the technical qualifications for “pollution,” or “smog,” but that’s stretching it a bit. This also depends on whether or not one defines smog in terms of the presence of fine particles, or in terms of the creation and presence of ozone, NO[sub]2[/sub], and PAN (peroxyacetylnitrate), which are the chemical compounds that make up smog as it is traditionally understood. (Regardless of that, Sam’s claim that “The same condition can be found in the ‘Blue Ridge Mountains’. The ‘Blue’ comes from the constant presence of ground-level ozone and hydrocarbons, emitted from the trees,” is class A disinformation – trees do not release ozone.) Finally, we must also consider quantity: do trace amounts of fine particles, ozone, NO[sub]2[/sub], and PAN in an atmospheric sampling really imply the presence of “smog,” or “pollution,” as the terms are commonly used?
I submit that the isoprene emitted by trees in the Smoky Mountain biosphere does not lead to the formation of a significant “blue haze,” or to the creation of “smog pollution” up on the heights, despite “popular scientific” reports to the contrary. Nor are the Smokies covered in a “constant haze of these type of pollutants,” i.e., isoprene, as Sam clearly believes (isoprene, I repeat, is not a “pollutant.”) Rather, I argue, the “Smoky Mountains” got their name from the wisps of fog that often cloth their upper reaches in Spring, Fall, and Winter. And this fog, I claim, consists almost exclusively of water vapor.
In the last round of this discussion, Sam provides the following information to back up his claims:
…and then crows:
…revealing, alas, once again, the fact that he simply doesn’t know what he’s talking about – or that, at the very least, he is anxious to frame the facts in way that gratuitously supports his agenda.
The report Sam cites is part of an ongoing project at the TVA, in conjunction with the EPA, to study the production and concentration of so-called “fine particles” in the atmosphere. As noted above, these are particles with a diameter of less that 2.5 micrometers, and are primarily comprised of sulfates and organic carbon. Unfortunately, Sam fails to understand (or chooses to ignore) that the project attempted to measure carbon particles exclusively, which in turn comprise only a portion of the total pool of fine particles found in the air. He therefore conveniently skips over the paragraph directly following his quote, which clearly states:
Thus, his claim that “50 to 90 percent of the ‘smog’ in the Smoky mountains comes from natural vegetation emissions,” is a complete misconstrual – and a very long way from the 80% originally claimed by Reagan.
In addition, we run into a definition problem here. The study makes no claims whatsoever about the abundance of NO, NO[sub]2[/sub], ozone, or PAN – the chemical components of what is traditionally understood as “smog” – at all. In fact, without the presence of man-made NO, isoprene cannot be converted into photosynthetic smog or produce ozone. So I am at a loss. Does Sam shift his definition of “smog” when convenient? Is it on occasion PAN/ozone, and on other occasions fine particle mass? Does a fine particle mass of 3 to 8 micrograms (a microgram is 1 millionth of a gram) of carbon per cubic meter of air constitute a “smog?”
In fact, at least according to the EPA, isoprene itself is not implicated in production of “haze,” which is the result of quantities of fine particles in the atmosphere (and is not the same thing as “smog,” by the way). The EPA has currently set a standard of 15 micrograms of PM2.5 per cubic meter air, a level which is proving difficult to meet for many areas of the Southeast, admittedly due to the combination of man-made and natural sources for these particles. Nevertheless, judging from the TVA report above, if we were to remove all human-generated sulfur and fossil-fuel sources of fine particles from the atmosphere, then the concentration of PM2.5 would fluctuate at a natural rate of between 2 and 6 micrograms per m[sup]3[/sup]. And of that quantity, an unknown amount is the result of “combustion of wood and agricultural wastes” – that is to say, is also man-made. In fact, the report speculates that the spike in “modern carbon” recorded during October 2001 was caused by “the burning of wood for heating, the burning of agricultural wastes, and forest fires.” Regarding the findings of this particular study, a related page summarizing the work done on the issue so far notes:
The TVA air samples were gathered at Look Rock. If one were to visit Look Rock during the spring or summer (as I did many, many times in the days of my youth), you would be hard pressed to note any sort of “haze” or “blueness” among the branches. In fact, Look Rock is in the foothills, and seldom becomes particularly foggy at any time of the year – and especially not during the summer, despite the inordinately high levels of PM2.5.
Sam:
Sorry, but I fail to see how the willful misrepresentation of scientific findings falls into the category of “fighting ignorance.”