NEW YORK (Reuters) - Consumers who see planting trees as a way to fight global warming can now sprout them without getting out the garden tools.
The U.S. Forest Service and non-profit group the National Forest Foundation launched a Web site on Wednesday where consumers can pay a $6 to offset one metric ton of carbon dioxide, the main gas scientists link to global warming. Their donations will pay for projects like the planting of ponderosa pines in a Montana forest wiped out by a fire, or Douglas firs in an Idaho forest damaged by a tornado.
"I think people are looking for something they can actually do besides reducing their carbon footprint," Bill Possiel, NFF's president said in an interview.
The world's largest emitter of greenhouse emissions, the United States, does not regulate output of the gases. That has helped spawn a voluntary, unregulated carbon market where consumers and companies pay someone else to cut emissions elsewhere at projects, such as wind power and tree farms.
Global voluntary market trade last year hit nearly 24 million tonnes of carbon dioxide credits worth more than $90 million, according to industry watchers.
Not every scientist agrees that planting more trees in the United States will cut greenhouse emissions. Ken Caldeira, a climate expert at the Carnegie Institution at Stanford University, says restoring forests outside the tropics will do little or nothing to stop climate change.
Trees absorb more sunlight than the ground so they can add to warming, according to Caldeira. The effect rises when the ground is covered in snow, which reflects the sun's heat back into the atmosphere.
Possiel said he was unaware of studies that say more trees outside the tropics can lead to more warming.
"We feel confident that the projects that we're proposing...will in fact sequester carbon and we have built in third party verification to make sure that is the case," he said.
The Forest Service estimates that the country's forests absorb 10 to 15 percent of U.S. carbon emissions, and the number could be boosted with more trees.
Some critics like Frank O'Donnell, president of non-profit group Clean Air Watch say consumers participating in voluntary carbon markets risk lulling themselves into thinking that they have cleared their guilty feelings and don't have to do anything else to fight warming.
"This is not being proposed as a solution to climate change," said Possiel, who said planting trees also helps entire ecosystems. "We're not trying to market this idea as an absolution for sins, it's a way that each of us can do something that has multiple benefits besides carbon."