Well I don't know the guy so will have to take your word on that.
Is not the NASA stuff about organic matter doing well because of the CO2 new information? I don't, I must admit to not really researching it properly, but that is mainly because I don't have time. I don't believe that should exclude me, it should mean I should be aware that the information could be false but then I am not basing my opinions on it, just using it to question the assumptions we have made.
I don't really like these debates because if you question anything you are seen as a bit of a nutter, even if you accept the premise, and then you have the idea that you are supposed to research every link someone has posted exhaustively before you should be allowed to comment on it.
Sure, if this was parliment and we were making the Laws, but we aren't and we ain't. For the simple matter of discussion I don't think we need to be professional climatologists.
OK, let's get into this in a little more depth then...
1 - It's long been recognised, and indeed demonstrated pretty much conclusively by proper scientific experiments that increased CO2 levels lead to increased plant growth. It's why greenhouse growers have added CO2 to their greenhouses for decades (though this is slightly different because a greenhouse is essentially a closed / semi-closed system which if left to it's own devices will have co2 levels significantly below those of the air outside due to the plants absorbtion of the co2, so without adding co2 to the system, co2 levels will fall to levels so low that plant growth virtually stops).
2 - This has also long been recognised as a positive feedback mechanism within the anthropogenic co2 induced climate change hypothesis... I can't be arsed right now to search through the IPCC report to find references to it, but I was taught about it at uni 12 years ago when discussing the various positive and negative impacts of increased co2 levels.
3 - The climate change / co2 issue is a complex issue with many constituent parts, and in deciding upon whether action needs to be taken to stabilise CO2 levels all factors need to be taken account of. To do this you'd take account of all the known and potential positive impacts, and all the known and potential negative impacts of all the various factors, together with the certainty levels (ie how certain the science is behind each factor) to get an overall view of the need to stabilise co2 or not. This is what the IPCC has done, and concluded that the positive effect of increased CO2 levels on increasing plant growth do not offset the negative impacts of increased co2 levels enough for business as usual to be a sensible policy... ie, yes you will get increased plant growth, but the other changes resulting from increased CO2 levels are predicted to cause much more damage, therefore the overall effect of increased CO2 levels is strongly negative.
Bigfish appears to be arguing that because increased Co2 levels mean increased plant growth nothing else matters... this is fine from his position, because he doesn't believe that increases in CO2 will have any real impact on climate at all. If bigfish's hypothesis on the other effects of increased CO2 levels were to be correct, then I would almost certainly agree with him that pumping more co2 into the atmosphere to increase plant growth is a great idea. Unfortunately he has yet to produce a single scrap of evidence that this is the case (well any evidence that hasn't been fully discredited on these boards for anyone to see).
4 - You also might like to consider exactly how much of this 6.2% increase in the last 20 years or so is actually down to increased CO2 levels rather than other factors. We've already discussed the idea that 42% of this increase is actually down to reduced levels of cloud cover in the amazon basin allowing more sunlight to reach the plants at ground levels rather than being reflected back out to space by the clouds (post 28 by bigfish of all people, from sciencemag).
Another major factor is the global decrease in sunlight reflecting aerosols over precisely the timescale that this increase in Biomass production has been taking place. Essentially reflective aerosols prevent a significant proportion of the sunlight from ever hitting the ground, and less sunlight = less plant growth. this effect is particularly strong at high lattitudes as the sunlight has to pass through much more of the atmosphere to reach the ground (as it's coming in at an accute angle rather than straight down as at the equator).
This graph from nasa of total global average light reflective atmospheric aerosol content should give a decent idea of this reduction.
[
sourece=nasa]
note that aerosols not only have a direct impact on solar radiation hitting the ground by the light that reflects directly off the particles themselves, but this impact is multiplied by increased cloud cover as clouds form around the particulates.
so to conclude... yes Bigfish is correct, increased Co2 levels will have beneficial effects in terms of total organic growth rates. However much of the increased growth rates we've seen are likely to be attributed to factors other than CO2 levels, and the remaining incrased growth rates attributable to increased CO2 levels would in no way compensate for the other problems caused by increased Co2 levels.
hope this helps
eta - ketchup
