STEVE INSKEEP, host:
Now, let's go to a not so noisy environment - the redwood forests of California. There's an experiment going on, there, to turn trees into what are called carbon banks. The idea is to manage forests so they absorb more carbon dioxide from the atmosphere and slow down global warming.
At next month's big climate meeting in Copenhagen, one proposal is to pay countries to do this. As NPR's Christopher Joyce reports, California has already started.
CHRISTOPHER JOYCE: For carbon banking you need carbon accountants, people who can put hard numbers on how much carbon trees breathe in and out. Some of these accountants can be found in the Big River forest, a mountainous swath of oak, Douglas fir and redwood in Mendocino County.
On a rain-slick road, tractors are unloaded from trailers for a day's logging. But the Conservation Fund, an environmental group, has bought 16,000 acres of this forest and put it aside for an experiment.
This part of the forest is hardly pristine. A walk along a muddy trail with the Fund's Chris Kelly takes us through thick undergrowth and small trees � the kind of forest that comes up after heavy logging.
Mr. CHRIS KELLY (Conservation Fund): This forest, if you look around, you see it's very dense. You almost - in some places you couldn't walk through it. It's as if you just cast out seeds on the ground in your garden and then didn't come back and weed it. As a result, you get a choked garden with skinny carrots and under-ripe fruit.
JOYCE: But that's just the kind of forest the Conservation Fund is banking on -literally.
Mr. KELLY: So what we're trying to do is come in and thin the forest, and leave the bigger trees to grow. And as a consequence of that thinning, they will grow bigger, faster.
JOYCE: In essence, what these foresters are doing is weeding out some trees so that the remaining forest will grow faster and absorb more carbon that it does now. This is where the accounting comes in. It's tricky. If you cut down a tree, its carbon goes up into the atmosphere. So foresters here, have to prove their weeding will produce a net gain - more carbon stored in the trees that remain and grow than is released when the foresters weed. That means measuring, lots of measuring.
Mr. MADISON THOMPSON(PH) (Forestry Technician, The Conservation Fund): I'm Madison Thompson. I'm a forestry technician for the Conservation Fund. First things first, we're going to find how much downed wood there is within a one-tenth-acre radius. That's one of the things that we measure.
JOYCE: Downed wood, meaning fallen trees, tree limbs, even big branches. When they eventually rot, they emit carbon. They're liabilities in the balance sheet.
Mr. THOMPSON: Watch for the poison oak, point it out when you see it.
JOYCE: Thompson and his colleague Liz Forwin(ph) are covered head to toe in rain gear. It's steep and overgrown with ferns and poison oak. They scramble down a ravine and crawl up the other side to measure a stand of young redwoods. The redwoods are the assets, like the bank vault, where the big carbon gets stashed away year by year.
Jordan Golinkoff is the fund's mathematician. He keeps the balance sheet.
Mr. JORDAN GOLINKOFF (Mathematician, The Conservation Fund): Redwoods are kind of amazing because they can grow for hundreds and hundreds of years and still be, you know, measurably increasing in size and growing.
JOYCE: Most of the redwoods here are fairly young so they have a lot of growing ahead of them.
Ms. LIZ FORWIN (Forestry Technician, The Conservation Fund): Twenty-five.
JOYCE: Twenty-five inches?
Ms. FORWIN: Yeah.
Mr. THOMPSON: Yeah.
JOYCE: A typical 25-inch diameter redwood can store about a ton of carbon.
Mr. GOLINKOFF: If I wrap the tape around this tree and measured it and I knew its height roughly, you know, I can get a volume. And then once you know the mass, carbon is roughly 50 percent of the mass of most trees.
JOYCE: The fund calculates that over two years, their forest has soaked up an extra 350,000 tons of carbon. That's roughly equivalent to taking 80,000 cars off the road for a year. And Golinkoff says there are other benefits.
Mr. GOLINKOFF: By managing for carbon, we're not going to be harvesting as much, and harvest disturbs the soil, harvest reduces the size of the trees. And so, in general, when we have bigger trees and less disturbance, you have -creeks like this are shaded. They stay cooler. Fish like that. Creeks like this have less sediment running into them.
JOYCE: Okay. Now, you've banked your carbon, so what's it worth? Well, the fund is actually making money from Big River by selling carbon credits to people trying to green up their image or who want to offset their carbon footprint. Every ton of carbon is worth one credit.
It's a small market now, mostly in California. But it's growing, and negotiators in Copenhagen want to do the same thing around the world.
Gary Gero runs the Climate Action Reserve, which sets standards for carbon trading in California. He says once you legally limit carbon emissions, carbon banking starts to make business sense.
Mr. GARY GERO (President, Climate Action Reserve): Businesses in California said, we know you are going to regulate this someday, so give us the ability to start now reducing greenhouse gas emissions and ensure that we are recognized for those reductions.
JOYCE: And that, adds Gero, gives people who own forests a new option.
Mr. GERO: Whether or not they're going to be driven towards the timber industry or whether they can actually make a living at being a carbon supplier.
JOYCE: With next month's Copenhagen conference looking less likely to produce a grand and new climate plan, negotiators are now talking about some sort of forest carbon deal instead if they can figure out how to do the accounting.
Christopher Joyce, NPR News.