This forum is about wrong numbers in science, politics and the media. It respects good science and good English.
Charles might be on to something there. Freeman Dyson made the case that our control of land use (i.e. increasing the amount of vegetation, and especially preserving rainforests) could be a much more effective means of countering climate change than limiting fossil fuel usage, if we take the orthodox scientific views on the role of CO2 in the atmosphere for granted. Ironically, in Brazil, they have cut down great swathes of rainforest in order to create arable land for the production of 'green' biofuels.
I believe I read that the efficiency of the tree as a mechanism to remove CO2 and release oxygen is a function of its age. The older the tree the less effective it is and then it dies and releases its CO2.
Nominally this is "carbon neutral" behaviour and OK but at any one time the tree population may have a different age distribution and of course, man has been messing about with logging since he left the caves and we might suggest that now is when we have the biggest impact.
Of course, this has an analogy to the UK population... we are tending toward an older much more mature population, all wanting to draw pensions, much to the governments annoyance even though it defends its right to enforce retirement upon us, like it or not.
So here, over recent years, we have had an explosion of Greenie sponsored tree planting (I'm all for it, more trees and fewer houses) much like a post war baby boom. It means an awful lot of trees will mature together and die together, spiking the data some when.
Of course, we went through this during the Napoleonic wars when we denuded the countryside to build Nelson's navy and Evelyn was behind the move to reforest the country and here we are again with yet more initiatives. Curiously, the most beneficial tree management was probably to support the paper industry.
Anyway, that's a poor solution for the greenies because it means to maintain the most effective forests you need to keep cutting them down and replanting and they like virgin forest or primary forest best of all.
I have, of course, taken a button and sewn a vest on it, so from my scant data I have constructed a rather suspect scenario and it would help if someone out there could comment.
The position on whether old forests are carbon sinks is quite confused. The 'traditional' view amongst ecologists is that they're carbon neutral but there was a comprehensive study published last year suggesting that most of them actually do act as carbon sinks.
On the other hand old Canadian forests are net emitters of CO2 apparently due to infestation by mountain pine beetles:
The OCO satellite which failed to make it into orbit last month was supposed to identify carbon sinks from space and sort out this kind of issue.
The question is, who benefitted more from this satellite being prevented from making it into space (it was obviously thwarted ;-) ): The Greens or the Deniers.
Another point worth mentioning is that some people think that the forest area in South America is actually increasing, not decreasing. There is a tendency for people to give up farming and move into cities, and 'secondary forest' springs up rapidly on the abandoned farmland.
This newspaper article discusses the issue:
"These new “secondary” forests are emerging in Latin America, Asia and other tropical regions at such a fast pace that the trend has set off a serious debate about whether saving primeval rain forest — an iconic environmental cause — may be less urgent than once thought. By one estimate, for every acre of rain forest cut down each year, more than 50 acres of new forest are growing in the tropics on land that was once farmed, logged or ravaged by natural disaster."
These new secondary forest areas will have a better cO2 absorbing capability than mature rainforest.
This is analagous to the argument that North America was actually a net sink for carbon during the 20th centurry as re-forestation of the massive area logged during the 18th and 19th centuries took place. I haven't looked at the maths, but the whole of New England was essentially treeless by the mid-1800s and it certainly is't any more.
Of course people of a certain complexion want to argue that a tropical forest is so much more valuable than a temperate forest, but from a carbon sink standpoint, this is just crap.
I would also challenge the suggestion that crop plants doen't account for significant carbon fixation - yields from the major crops have gone up at least 4-fold per hectare in the past 50 years. Now that is a significant fixing of carbon, even if only temporary as it wil be recycled faster than wood from trees.