September 29, 2004

ONE LAST SCORE FOR THE GIPPER (via Robert Schwartz):

Study: Emission of smog ingredients from trees is increasing rapidly: Changes in forestry and agriculture affecting ozone pollution (Steven Schultz, 28-Sep-2004, Princeton University)

While clean-air laws have reduced the level of man-made VOCs (volatile organic compounds), the tree-produced varieties have increased dramatically in some parts of the country, the study found. The increase stems from intensified tree farming and other land use changes that have altered the mix of trees in the landscape, said Drew Purves, the lead author of the study that included scientists from four universities.

"There are seemingly natural but ultimately anthropogenic (human-caused) processes in the landscape that have had larger effects on VOC emissions than the deliberate legislated decreases," said Purves.

Although scientists knew that trees contribute substantial amounts of VOCs to the atmosphere, the rate of increase in recent decades was previously unrecognized. "If we don't understand what's going on with biogenic (plant-produced) VOCs, we are not going to be able to weigh different air-quality strategies properly," said Purves. "It's a big enough part of the puzzle that it really needs to go in there with the rest."

The study may help explain why ozone levels have not improved in some parts of the country as much as was anticipated with the enactment of clean-air laws, Purves said. Environmental technologies such as catalytic converters and hoses that collect fumes at gas pumps have substantially reduced human-produced VOCs. However, in some parts of the country -- particularly the area extending from Alabama up through the Tennessee Valley and Virginia -- these improvements may have been outweighed by increased VOC emissions from forests, mainly because of tree growth in abandoned farmland and increases in plantation forestry. [...]

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."

Somewhere he smiles.

Posted by Orrin Judd at September 29, 2004 2:45 PM

Let's see, the number of forested acres has been going up, and so the amount of these gases has been going up, so it's all humanity's fault. Sound's like another argument for increased clearcutting to me.

Posted by: Raoul Ortega at September 29, 2004 2:49 PM

Yet one more reason (including being
downwind from lots coal plants) that N.H.
has a distinct smog problem in the Summer
despite being one of the most densely forested

Posted by: J.H. at September 29, 2004 3:35 PM

New England is more forested now than it was at independence. It would be astonishing if that didn't have some environmental effect. (Actually, it probably correlates better with global warming than man-made CO2 emissions.)

Be Green Like Ron and George: Clear Brush For Our Children's Future.

Posted by: David Cohen at September 29, 2004 3:35 PM

And let's not forget "acid rain". What was being blamed on midwest coal fired powerplants was actually due to the runoff from rainfall on granitic soils covered with highly acidic dead leaves from forests that used to be farms only a few decades earlier. ("Acid rain" was also responsible for problems in the Sierra Nevada, where all the coal fired plants are hundreds of miles to the east, against the prevailing winds.) But then who consults with soil geologists and hydrologists when the problem is obviously meteorlogical.

Posted by: Raoul Ortega at September 29, 2004 4:25 PM

It's hard to imagine that the spread of plow agriculture to tens of millions of acres of North and South America, Australia etc. in the past 200 years didn't add some impulses into the brew that creates climate.

Warm or cool? Who knows.

In 1985, I spent a fair amount of time flying over the Connecticut River Valley at 3,000 feet.

It looked like the forest primeval, but, as David notes, that valley was the breadbasket of North America and the Caribbean in the 18th century.

Planted acreage in the U.S. South peaked in 1860 and forest has been taking back the place ever since.

Posted by: Harry Eagar at September 29, 2004 5:15 PM

In one of Bill McKibben's books he rhapsodized about the untouched forest near his cabin, but it was then pointed out that the area had been logged in the 19th century, and so his forest primeval was only about 100 years old.

The Blue Ridge Mountains got their name from the smoggy haze given off by fir trees.

I'm leary of the "80%" in the quote, though.

Posted by: PapayaSF at September 29, 2004 7:36 PM

That should be "leery," of course.

Posted by: PapayaSF at September 30, 2004 12:33 AM

Of course trees give off toxic waste. They give off oxygen --- toxic waste from the point of view of anaerobic bacteria.

If environmentalists had been around two billion years ago, oxygen would have been illegal.

Posted by: Joseph Hertzlinger at October 3, 2004 1:45 AM