"How trees might not be green in carbon offsetting debate" article

[mcg]

http://environment.guardian.co.uk/climatechange/story/0,,2053447,00.html

How trees might not be green in carbon offsetting debate

· Planting may worsen warming, say scientists
· Environmental gestures 'useless' outside tropics

Alok Jha, science correspondent, Tuesday April 10, 2007, The Guardian

It may have become the penance of choice for the environmentally conscious individual, but planting trees to offset carbon emissions could contribute to global warming if they are planted outside the tropics, scientists believe.

They argue that most forests do not have any overall effect on global temperature but, by the end of the century, forests in the mid and high latitudes could make their parts of the world more than 3C warmer than would have occurred if the trees did not exist.

...
Dr Caldeira warned that chopping down trees outside the tropics was not a good idea. "Preservation of ecosystems is a primary goal of preventing global warming, and the destruction of ecosystems to prevent global warming would be a counterproductive and perverse strategy."

Dr Bala added: "Apart from their role in altering the planet's climate, forests are valuable in many other aspects. Forests provide natural habitat to plants and animals, preserve the biodiversity, produce economically valuable timber and firewood, protect watersheds and indirectly prevent ocean acidification."

...

[NNadir]

1. I hear this sort of thing all the time, but I don't believe it.

A tree planted in previously <em>open</em> space obviously sequesters carbon on a ton scale.

Forests themselves are in equilibrium, of course.

It is clearly important to do what we can to protect the tropics. But places like these are under pressure. I had a long piece some time ago about Cameroon, where some of the world's most important forests are being destroyed for firewood and lumber exports. But I don't know how to tell the Cameroonians to die instead.

[jwirr]

2. There is also the issue of ground water levels and trees. When

an area is denuded the water levels go down or at least I think they do.

[Dead_Parrot]

6. You could tell them...

...that there's no truth to the rumour that their axes contain radioactive material, and that they are perfectly safe. Experience suggests the Cameroonians will immediately bury them all in a deep pit and never go near them again.

[htuttle]

3. They're confusing local climatic effects with global ones

While trees warm local environments in a number of ways, they help reduce global warming in the long term far more by removing carbon from the atmosphere.

They're engaging in very short term thinking here.

[wtmusic]

4. Short-term, and small-scale

The amount of energy absorbed by trees worldwide is microscopic compared to the amount of energy prevented by CO₂ from radiating back into space.

This reminds of the role of the sunspots in global climate, elevated to importance by GW deniers only by the volume of their rhetoric.

[greenman3610]

5. trees= soil

soil sequesters carbon