CREDIT: CanWest News Service Researchers now say forests can do little to improve the future climate or to lower the atmosphere's carbon levels. What they can do is make global warming worse.

OTTAWA - Canadians rely partly on our nation's forests to help save the world's climate. Now evidence says it's time to stop.

In Canada we know we burn too much coal, gas and oil, creating the "greenhouse'' gas called carbon dioxide.

But we have learned for years that in the fight against climate change, this country's vast forests too many trees to count pull carbon dioxide out of the air again, locking it up as solid carbon in branches, roots and trunks.

Just one problem, scientists now say. It's largely wrong.

Even as the federal government is poised to argue that our trees should reduce our Kyoto obligations, scientists say these supposed saviours have done about all they can to prevent global warming.

Forests can do little to improve the future climate or to lower the atmosphere's carbon levels. What they can do is make global warming worse.

In the late 1990s, a Canadian and American team of forest scientists went into the woods in northern Manitoba to do something never been done before. They wanted to measure carbon going into and out of a living forest, to learn how effectively the forest was sucking carbon dioxide out of the atmosphere and storing it. That's called being a ``carbon sink.''

They chose an area that belongs to the boreal forest the northern forest dominated by black spruce that is Canada's most widespread, and still most untouched forest.

What they found surprised many.

The team made 22,000 hours of intensive measurements of the soil, the surface of the ground, and all the way up through the 120-year-old forest past the canopy to open air.

They learned carbon goes both ways.

From late May through July, new growth made the spruce forest ``inhale'' one to one and a half grams of carbon per square metre of forest per day. In August and September, the hottest, driest period, the rate of carbon dioxide movement fell to about zero.

But in the late summer and fall, the forest ``exhaled'' carbon back into the atmosphere at a rate of a little less than one gram per square metre per day, as warmer soil allowed soil bacteria to digest organic matter and release carbon dioxide. This fell to a much lower rate through the winter.

Overall, in three of the four years they measured, the forest was putting slightly more carbon into the air than it took out a bad thing, if we want forests to store this material. The fourth year, the balance tilted the other way: The forest sucked out and stored carbon but not a lot of it.

``Forests on average certainly exchange a lot of carbon with the atmosphere,'' team leader Steve Wofsy of Harvard University said in an interview. ``So if you want to say: `Do they remove a lot of carbon from the atmosphere?' yeah, sure they do. Do they put back a lot? Sure, they do that, too.''

But what about all the other forests, the southern ones with their maple-beech-oak hardwoods, and their pines and aspens? Aren't they cleaning our air?

Unfortunately, said, Bill Schlesinger of Duke University, even these forests are generally in a steady state in terms of carbon production and sequestration.

``And so you can't really count on them as a big sink,'' he said.

Yes, he acknowledges, many people do make the claim that forests will counteract our car-driving, coal-burning ways.

``Oil and coal companies love to say that. So do various forest services,'' he said. ``It sort of gives them a raison d'etre.

``But the idea that they're going to combat the rise of CO2 in the atmosphere has, I think, probably been overstated. If you disturb them,'' by cutting them down or burning them, ``then they may exacerbate the rise of carbon dioxide.''

This could be disappointing news for many of Canada's political leaders, who have been counting on credits under the Kyoto Protocol for Canada's forest ``sinks.''

If your forests are taking up carbon, the United Nations Framework Convention on Climate Change says, then you don't have to do as much to stop burning coal, oil and gasoline.

Canada has until Jan. 1 to decide whether it wants to include forests as ``sinks'' to gain credit for cleaning up the greenhouse. Federal and provincial government experts haven't finished going through the numbers.

But here's a twist.

All that matters in this accounting is whether our forests suck up carbon for a brief period 2008 through 2012, the time covered by the Kyoto deal. We could claim a credit if managed forests showed a burst of regrowth, and probably with an aggressive campaign to limit forest fires, during this period. Results would have to be audited during this period. But this type of accounting looks only at short-term, temporary changes, with no regard for the long-term reality.

Federal scientists know the forests are not going to help much. But in the short run they say forests may be able to suck up some carbon that they will release again later, after the accounting period. It's like a boxer purging to get his weight under a limit in time for a fight, with no thought of staying at that weight afterward.

Ottawa Citizen