Digging In to Cool the Planet

By Sandy Bauers
Philadelphia, PA (November 25, 2007)- All over, volunteers are giving planting trees a green thumbs-up. Planting a tree used to be such a simple thing. For many, it was a simple act of beautification. Or perhaps a way to shade a patio. But lately, planting a tree has been elevated to a cause, a mission, a step- however tiny, as skeptics note- to stall global warming.


In cities throughout the country, in countries around the planet, volunteers are muddying their knees and dirtying their fingernails as they plant more, more, more!
Southeastern Pennsylvania’s TreeVitalize program is finishing up a mammoth tree-planting spree- more than 14,000- this fall. The largest will count toward a four-year, $8 million, 22,000-tree goal for the partnership. Next month’s final tally is expected to exceed it. Handily.
Baltimore aims to double its tree canopy. Seattle wants to plant one for every citizen- 650,000. Los Angeles has a target of a million. The grandaddy of efforts is surely the United Nations Environment Programme’s goal of a billion trees. All in 2007. The target is in sight. More than 655 million have been planted, according to a tally on its Web site, and pledges have topped 1.4 billion.
Every third grader gets the gist: Animals exhale carbon dioxide; trees absorb it. Unfortunately, cars, trucks and power plants spew tons and tons of the greenhouse gas into the atmosphere, where it is clearly helping to warm the Earth. Trees can help reverse that. They combine carbon dioxide with water and sunlight to make complex sugars that become new tree tissue, the process called photosynthesis.
The carbon stays. The exact amount is what foresters have been gauging with increasing accuracy and an ever-expanding database. A U.S. Forest Service report released in December parsed the mitigation potential of Philadelphia’s 2.1 million trees to this: They store 530,000 tons of carbon, and each year, in new tissue, they sequester an additional 16,100 tons – an overall value of nearly $10 million. It’s the equivalent of the city’s emissions for 22 days, or the annual emissions of 318,000 automobiles.
Trees also help “avoid” emissions by shading buildings, which then require less power-hungry air-conditioning. One forester figures urban trees will become so vital in a new carbon-centric world that their performance will be strictly monitored. Society will no longer have the patience to coddle sick or stunted trees. They will be yanked and replaced.
Traditional forests are a different matter, but even those are being seen through a carbon lens. Pennsylvania’s 17 million acres sequester 4 percent of the state’s carbon emissions. Nationwide, forests offset 11 percent of emissions – proof that “forests aren’t just a trivial part of the global climate balance,” said Brian Murray of Duke University’s Nicholas Institute for Environmental Policy Institutes.
“In the past, the value of a tree in the forest was greater when it was dead and turned into a product” like furniture or paper, said Greg McPherson, director of the U.S. Forest Service’s Center for Urban Forest Research. “Now we’re recognizing the ecosystem services of forests.”
Pennsylvania’s Department of Conservation and Natural Resources has been working for more than a year on a report, due in December, looking at how to manage trees better. And get more of them. “We’re looking at these resources in a new way,” said John Quigley, the department’s legislative director. “In the rise of carbon markets, is there an economic value that we can take advantage of?”
Not that concerns haven’t arisen. Especially when it comes to massive tree “plantations,” which are chemical-dependent monocultures. This fall, columnist Ted Williams launched a tree diatribe in Audubon magazine. He took a jab at Joyce Kilmer’s “cloying little ditty” and fretted that rampantly “jamming seedlings into the ground” as carbon offsets could amount to little more than a greenwash for polluting businesses and profligate consumers. Cambridge University naysayer Oliver Rakham has said planting trees to prevent global warming is akin to telling people to drink more water to keep down sea levels. Partly, he clarified in an e-mail, because trees just can’t do it all.
Proponents respond with a politer version of “Well, duh!” “If you’re under the misconception that if I plant a tree, I can drive an extra hundred miles… no. You can’t buy off the forgiveness,” said the Morris Arboretum’s Bob Gutowski.
TreeVitalize’s project director, Patrice Carroll, who is kind of the 411 of tree-planting in the region, said she didn’t think people expected that. Tree-planting “connects people to nature,” she said. “It gives them a bigger stake in the issue.” They might drive less, not more.
Just like changing a lightbulb or turning down the thermostat, “when you aggregate those individual actions over a broad scale, they are meaningful and important,” said Quigley, who noted that the Department of Conservation and Natural Resources would like to see TreeVitalize expanded across Pennsylvania.
Anyone can plant a tree, and they can do it without federal legislation. So they do. When Philadelphia’s Air Management Services found itself with discretionary money from air-pollution fines, it gave $340,000 in grants to the Fairmount Park Commission to plant 2,400 trees in the city.
In addition to storing carbon, trees absorb pollutants, said Alison Riley, Air Management Services’ coordinator of voluntary programs. “They affect people right here in our city.”
Weekend after weekend this fall, TreeVitalize volunteers planted away. Nearly 90 trees went into the ground near Passyunk Square in South Philadelphia, 60 in Oak Lane, 65 in East Falls. About 800 trees and shrubs went into the ground at a Montgomery County stormwater retention basin, 3,400 at the Stroud Preserve in Chester County.
“Certainly, we must transform the way we produce and consume energy,” McPherson noted in a rebuttal to tree-planting critics. But “doing so will require the brightest minds of science, the staunchest will of politicians, and a great deal of time, effort and money.
“In the meantime, we can all plant a tree.”
For the full article, visit the Philadelphia Inquirer.
Related Resources:
Pennsylvania Horticultural Society
Center for Urban Forest Research