Study Suggests That Canadian Boreal Forest Has Switched To Net Carbon Source, Not Sink-

[hatrack]

Forests have long been thought of as an ally in the fight against global warming, but a new study suggests that Canada's boreal forest may in fact be releasing more greenhouse gases than it absorbs. "The boreal forest, at least in the north-central part of Manitoba, has gone from a weak carbon sink to a weak carbon source," said Dr. Tom Gower of the University of Wisconsin, whose paper is being published Thursday in the journal Nature. "It is now contributing to atmospheric (carbon dioxide) concentration."

Gower and his fellow researchers studied a million-square-kilometre stretch of forest around Thompson, Man. The team took field measurements of how carbon moved between the forest and the atmosphere and then used computer modelling and forestry records to suggest how that cycle has changed since the 1950s.

Trees absorb carbon dioxide as they grow and release it when they burn or decompose. Although results varied for individual years depending on the severity of the forest fire season, Gower found that the forest once absorbed, on average, slightly more carbon than it emitted - about five or 10 grams per square metre of forest per year.

Now, however, the direction of that flow has reversed. On average, the forest actually emits about two grams per square metre per year. "(The forest) is actually contributing to rising carbon emissions," Gower said. The cause, he said, is forest fires. Climate change, according to most models, leads to increased forest fires because it creates hotter and drier conditions. "The warmer climate has increased fire frequency and extent," said Gower. "Those wildfires have caused this transition in the boreal forest from a carbon sink to a carbon source."

EDIT

http://canadianpress.google.com/article/ALeqM5igPzr49ppvSTb3YRwsOYiKVv22gg

[applegrove]

1. Not to mention the pine beetles. They kill alot of trees that then rot.

[GliderGuider]

4. And they become fuel for the fires.

I heard Dr. Gower interviewed on CBC radio last night. Smart, aware, articulate - he really had his crap together. He says there is no way we can deal with this, because it's all caused by climate change, it's probably happening all across Canada, the amount of material involved is too large for human intervention, and in any case the forests where it's happening are inaccessible. I wonder if in 20 years we'll be seeing Australia-style wildfires in the Canadian boreal forest?

He did say the effect is small. The forests have gone from being sinks of 0.1 tonnes/ha/yr to emitters of about 0.1 tonnes/ha/yr. This could put a crimp into things like the billion-tree campaign, though.

[gulfcoastliberal]

2. Abrupt climate change achieved - runaway warming initiated.

Humanity & civilization now critically endangered. Interesting times.

[tom_paine]

3. Sounds like the buffering capacity of the Earth is just about gone

Any chemists, biologists, or others know what happens to a solution or a system once the buffering capacity is used up?

Here's a graphic representation of this very common (in biology and chemistry both) process.

[amandabeech]

5. I wonder how long it will take before natural reforestation takes place.

I would expect a less dense forest with some difference in species.

I hope that the soil has not burned deep like it has in some of the most intense fires. The fire burns the organic matter in the soil, as well as ungerminated seeds that would help bring back the forest. I wonder if it might be worthwhile to try mixed planting of native species thought to be more tolerant of drier conditions, all of trees, bushes and annuals. I know that it is best to let nature take its course, but we may not have time.

I know that it sounds silly, but perhaps we need to bring back Arbor Day. Encourage more landscaping with trees and shrubs and run a PR campaign against vast expanses of grass and annuals. In addition to locking up more carbon, trees and shrubs can help limit water runoff during strong downpours, returning more water to aquifers and less to the sewage system.

[NNadir]

6. Well, that's not all that surprising, is it? K&R.

[NNadir]

7. Whoops. I can't recommend. I apparently missed it more than 24 hours ago.

[Kolesar]

8. Now I'm mad.