October 19, 2004
Air Pollution From Trees Increasing Rapidly

A number of factors have combined to increase volatile organic compounds (VOCs) air pollution from trees faster than VOC pollution from humans has declined.

They calculated that vegetal sources of monoterpenes and isoprene rose by up to 17% from the 1980s to the 1990s equivalent to three times the industrial reductions.

The three major contributing factors are the natural reversion of abandoned farm land to forested land, the invasion of sweetgum trees, and the growth of large forests of pine trees for lumber.

Princeton University post doc Drew Purves got to the bottom of the tree pollution problem.

Further studies at Princeton and the federal Geophysical Fluid Dynamics Lab at Princeton are using sophisticated computer models to estimate the changes in ozone caused by the changes in tree-produced VOCs. Purves noted that interactions between VOCs, NOx and ozone are complex -- some may actually lower pollution -- so it would be premature to base environmental policy on studies of VOCs alone.

Purves, a postdoctoral fellow, wrote the article in collaboration with Stephen Pacala, professor of ecology and evolutionary biology at Princeton, as well as John Casperson of the University of Toronto, Paul Moorcroft of Harvard University and George Hurtt of the University of New Hampshire. The article is scheduled to be published later this fall in the journal Global Change Biology.

The scientists conducted the study by analyzing data collected by the U.S. Forest Service, which measured and cataloged 2.7 million trees on 250,000 plots of land across the country. They calculated the VOC emissions for each tree and each plot and used their findings to map VOC levels nationally. The scientists compared survey data taken in the 1980s with those taken in the 1990s to determine how levels were changing over time.

They found that areas where farmland has been abandoned during the last century have early generations of trees that produce higher levels of VOCs than older growth forests. In the South, pine plantations used for their fast-growing supplies of timber have proven to be havens for sweetgum trees, which are major producers of VOCs. Indeed, virtually every tree that grows fast -- a desirable quality for forestry production -- is a heavy emitter of VOCs.

"It's just one of those biological correlations," said Purves. "What you want is a fast-growing tree that doesn't produce a lot of VOCs, but that doesn't seem to exist."

The truth is plain to see: Nature is dangerous and needs to be brought under greater human control so that we can have a safer and cleaner environment. This shouldn't be surprising. After all, where does typhoid come from? Nature. Where does the Ebola virus come from? Nature. Where do cholera, diphteria, malaria, and tuberculosis come from? Or tidal waves? Earthquakes? Rattlesnakes? Tornadoes? Floods? Avalanches? Black widow spiders? The asteroids that probably wiped out the dinosaurs? You already know the answer to all those questions. And what about air polluting volcanoes? They aren't operated by the petroleum industry.

Consider the irony for construction. If you build with concrete, steel, plastic, and other less natural materials you will reduce the need to plant trees and therefore fewer polluting trees will be planted.

Polluting trees also call into question the idea of using various kinds of biomass as energy sources. If we grow more stuff then that disgusting and dirty (hey, plant roots have dirt all over them) plant matter is going to release all kinds of pollutants into the atmosphere.

The findings also could raise questions about potential strategies for developing "green" fuels. One idea for cutting greenhouse gas emissions is to create "biofuels" from renewable tree plantations; however, these plantations may lead to increased ozone levels, the authors note.

What to do? Technology can provide the answer: plants used for biomass and trees grown for lumber need to be genetically reengineered to be less polluting. If better engineering designs can make cars less polluting then why can't better engineering clean up trees and other natural polluters as well?

Ronald Reagan came in for a lot of criticism when he warned of the dangers of letting trees run amok and ruin our air.

Noting President Ronald Reagan's notorious 1980 reference to trees causing pollution (Reagan said: "Approximately 80 percent of our air pollution stems from hydrocarbons released by vegetation."), the authors conclude: "The results reported here call for a wider recognition that an understanding of recent, current and anticipated changes in biogenic VOC emissions is necessary to guide future air-quality policy decisions; they do not provide any evidence that responsibility for air pollution can or should be shifted from humans to trees."

But obviously Ronnie was on to something. Where others have been lured into looking at towering Redwoods and seeing ancient stately majestic beauties reaching serenely into the sky Ronnie saw right through them like he saw through communist fronts. While the real effects of trees were invisible to the rest of us Ronnie clearly saw that trees were waging a silent war on Western civilization.

Update: One other point: The older trees in older forests pollute less. Tree population aging is a good thing.

Share |      Randall Parker, 2004 October 19 03:08 PM  Pollution Natural

Engineer-Poet said at October 19, 2004 5:37 PM:

Pardon me for my incredulity, but I honestly hope you're kidding about the "polluting trees" thing.  You only get photochemical smog if you add nitrogen oxides, which are mostly (though not entirely) a product of human activities.

If we want to get rid of the pollution issues, it makes sense to slash the use of internal combustion engines during the hot season.  As this outcome would be one of the results of most ways of slashing petroleum consumption, it makes sense to pursue the latter goal as a way of achieving the former.

Randall Parker said at October 19, 2004 6:14 PM:

E-P, I definitely found the story to be funny.

Jody said at October 19, 2004 6:46 PM:

Burn em. Burn em all.

p said at October 19, 2004 6:47 PM:

we need better definitions ... this research looks like an attempt to steer money in a new direction ...

Lazy Bones said at October 19, 2004 9:57 PM:

It's good to see the trees are fighting back against Western Civilization! Go trees go!

Randall Parker said at October 19, 2004 10:04 PM:

Lazy Bones, The trees are terrorists. They are all around us too. There are many more trees than people. They might decide to kill us in our sleep.

fingerowner said at October 20, 2004 8:03 AM:

First, cow flatulence. Now plant flatulence. Even Mother Nature agrees: fart = funny.

David A. Young said at October 20, 2004 10:28 AM:

Having lived in Florida since 1979, I long ago came to the conclusion that building homes out of wood is crazy. When you factor in mold problems, termites, fire vulnerability, energy efficiency, and noise abatement qualities . . . not to mention hurricanes . . . one of the numerous forms of concrete construction (block, ICF, pre-formed tilt-up, etc.) is definitely the way to go. ESPECIALLY in Florida, but in other climes, as well. This is just one more indicator that stick-built homes are a non-optimum solution to our housing needs. (No, I am not in the concrete-home construction industry; yes, this is a pet peeve of mine.)

wcw said at October 20, 2004 8:54 PM:

You see a wood-frame house and think about economics. Raised in a different part of the country, I see anything else and think about earthquakes.

David A. Young said at October 21, 2004 9:51 AM:

WCW, you're implication seems to be that properly built concrete single family dwellings are MORE vulnerable to earthquake damage than wood frame structures. I haven't read/heard this before, and can't find anything that suggests special susceptibility of concrete residences. Can you give me any references? Thanks.

kat kalay said at October 10, 2006 8:13 AM:

you got to be insane tree pollution ha! we from the wolfen clan know the problem the humans.

tom said at September 9, 2007 11:42 PM:

I think this whole topic about trees being the devil is a massive waste of time, rsearch and money.

red said at September 17, 2007 10:19 PM:

trees are life........ they give us oxygen and prevent us from destructive carbon dioxide....

Khoi said at November 1, 2009 9:37 PM:

"Changes in U.S. forests caused by land use practices may have inadvertently worsened ozone pollution, according to a study led by Princeton University scientists. The study examined a class of chemicals that are emitted as unburned fuel from automobile tailpipes and as vapors from industrial chemicals, but also come naturally from tree leaves. These chemicals, known collectively as VOCs, REACT WITH OTHER POLLUTANTS to form ozone, a bluish, irritating and pungent gas that is a major form of smog in the lower atmosphere." verbatim from the article from Princeton University

Whence those OTHER pollutants MOSTLY came from, if not from your beloved man-built factories and farms, Randy?

Khoi said at November 1, 2009 9:46 PM:

Moreover, New Scientist is NOT a peer-reviewed journal. The Princeton's study is 5-year-old.

Didn't you read the last line, Randy?

[T]hey [Princeton's researcher] do NOT provide any evidence that responsibility for air pollution can or should be shifted from humans to trees."

Are you the same Rabdall Parker Professor of Macro-OEconomics?

Bob Badour said at November 2, 2009 5:06 AM:
The Princeton's study is 5-year-old.

As is Randall's blog article. If you pay any attention, you will notice he wrote it in October 2004.

ED said at May 10, 2012 1:24 PM:

Oddly, when we lost all of our big trees in the back yard (lightening---massive strike)...everyone's health improved (it took about 3 months). Allergies gone
and no asthma either. Strange. Am I convinced there was a correlation? I'm not sure. I had posted it in http://www.majormedicalhealth.com
When we build another home next year, I'm not sure what to do about trees!

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