cohenite Says
"since humans breathe in air with a concentration of CO2 of ~390 ppm and breathe out air with a CO2 concentration of ~ 4000 ppm, why don't you, Geoff and like minded people solve the problem by holding your breath?"
I say
Since all the CO2 I breath out recently came from plants this does not increase the amount of CO2 in the air. On the other hand the co2 from fossil fuels comes from plants that grew 10s or 100s of millions of years ago. The isotope of carbon in CO2 tells that the origin of the increased levels of atmospheric CO2 comes from the burning of fossil fuels.

A quick calculation for you
typical breaths per min = 12
typical human exhales 1/2 a litre of per breath
Air breathed out is 4% CO2
Therefore one human exhales =0.04 grams (2g/L x .04 x .5L) per breath

Therefore in 24 hours one person exhales 24 X 60 X 12 X 0.04 grams= 692 grams
world's population is 7 billion in 24 hrs humans exhale 483,840 tons of CO2.
CO2 emitted from fossil fuels, industry and land clearing is about is about 35 billion tons annually or 96 million tons daily. so breathing works out at about 1/2 percent of the our daily emissions. It would seem that if we want to reduces our emissions of CO2 reducing our use of fossil fuels is more practical than your suggestion of not breathing.

I do not dispute that adding CO2 to the air generally increases plant growth but this is on a par with statements like crashing your car saves fuel. The net benefit of adding CO2 to the atmosphere for plants is so heavily outweighed by the negative impacts to the climate that no one who understood the science would advocate such a crazy idea.

Ok, so I took on board suggestions that I should look at the review paper under discussion and Dons suggestion that if I thought that there was "something shoddy about an aspect of the argument or evidence, then for goodness sake find the shoddiness and tell us what and why. That way we can argue about something important."
So, my second foray into 'mini-reviewing' Idsos work by random sampling didn't really go so well either. My methodology:
I looked for one of the first instances where he quotes a "%" figure from a paper and then I thought I would track down that paper and see if he interpreted it correctly. It turns out that it was Lin et al. (2010) on page 7, which is a meta-analysis of 127 studies.

Well, he scored ok for at least transcribing the figures correctly, but there is no evidence that he actually read the paper beyond the abstract, as all the quotes are directly from the abstract. If he read the paper he would have found that some plant types don't do so well from warming. If you are a leguminous or spore plant, you're not keeping up with the Joneses as it were. Lin et al. actually discuss this and include conclusions that "Dependence of the terrestrial plant biomass responses to warming upon PFTs [Plant Functional Types], geographic and climatic factors as well as warming magnitudes will have consequent influences on community composition and structure, vegetation dynamics, biodiversity and ecosystem functioning in a warmer world. "

This is also in the abstract but is completely missing from Idso's "review". The ecology will change significantly in a 'greener' world, and it is difficult to tell whether this is good or not, as some plant species will definitely decrease, as others increase, which will have consequences for the animals that live on them and the food chain. Idso never really seems to get past the "greener is gooder" type of reasoning. And this is only random sample #2.

Wow, I can only guess what will happen in my next random sample.

It's likely it is Providence supplying for the needs of the poor, population is reaching a peak then will decline in middle of century around the time global cooling begins, and food for the developing world is a necessity. God loves his children.

Matt 9: “Which of you, if your son asks for bread, will give him a stone? 10 Or if he asks for a fish, will give him a snake? 11 If you, then, though you are evil, know how to give good gifts to your children, how much more will your Father in heaven give good gifts to those who ask him!

Undeclared animosity toward God explains most of the ideas given prestige by the liberal ruling class. They're able to use any old flimsy screen to conceal their naked lust for power these days we are so much a flock of sheeple

warmair your calculations about howmuch human exhalation contributes to CO2 levels compared with fossil fuels may be a bit off:

http://micpohling.wordpress.com/2007/03/27/math-how-much-co2-is-emitted-by-human-on-earth-annually/

This calculation shows human breathing contributes as much as 8.9% as fossil fuel. Which is why AGW believers want fewer humans I suppose.

Bugsy: your critique of Norton [1999] linked to good old Dr Bert who says this:

“The response of the wetland to elevated CO2 has been increasing over this long period, rather than decreasing as many would have predicted”

And then uses that to assume that vegetation will cease to be able sequester the extra CO2 from AGW!

The 2nd Dr Bert link, which attempts to find a problem in the difference between C3 and C4 vegetations response to extra CO2, is just wrong. Did you even read the peer reviewed links I supplied before? The 2nd one said this on page 1110:

"Corn, sugarcane, sorghum, millet, and some tropical grasses use the C4 pathway, so named because the first products of photosynthesis have four carbon atoms per molecule. C4 plants also experience a boost
in photosynthetic efficiency in response to higher CO2 levels, but because there is little photo-respiration in C4 plants, the improvement is smaller than in C3 plants. Instead, the largest benefit C4 plants receive from higher CO2 levels comes from reduced water loss. Loss of water through leaf pores declines by
about 33% in C4 plants with a doubling of the CO2 concentration from its current atmospheric level.
Since corn and other C4 plants are frequently grown under drought conditions of high temperatures and limited soil moisture, this superior efficiency in water use may improve yields when rainfall is even lower than normal” (Wittwer, 1992)."

Your complaint about people not reading their references appears to be a problem with you as well.

Cohenite, could you please at least have the decency to put some water on that lettuce before you savage me with it?

A couple of points:
-I did not give a critique of Norton et al 1999. I have been giving micro-critiques of Craig Idsos work. Norton was merely an example (the FIRST random sample!) of how Idso doesn't maintain a database that is to be scientifically trusted.
-Good old Dr Bert is merely an example of people who conduct scientific research and experimentation on the nuances of the carbon cycle and its relation to ecology. Your critiques of his work are irrelevant and quite frankly would be insulting to a scientist, because your 'refutation' is a quote from a footnote in a Tim Curtin document published in Energy and Environment, which itself was originally from Wittwer (1992), which was published Policy Review (hint-NOT a scientific publication)! Oh and Good Old Time didn't even have the decency to reference the full and correct title of Wittwers paper.

In twenty years the arguments haven't changed, and you guys don't seem to like the primary research literature, you keep quoting review documents that were written by people with the same point of view, many of which are not reviewed, except perhaps by a copy editor.
And you think that I have a problem with not reading references?

Oh pulease.

cohenite says
warmair your calculations about howmuch human exhalation contributes to CO2 levels compared with fossil fuels may be a bit off:

http://micpohling.wordpress.com/2007/03/27/math-how-much-co2-is-emitted-by-human-on-earth-annually/
_______________________

I checked up to find the problem the method above is correct but he uses a figure of 24.136 gigatonnes for annual fossil fuel emissions based on 2007. The figure I use used was 35 gigatonnes based on 2010 which I obtained from the same source as your link above used.

I also made a mistake in that I lost a zero on the CO2 emissions by humans breathing the correct figure would appear to be around 5%.
I don't mind admitting when I make a mistake after all many years ago I thought that human emissions of CO2 would not be on scale large enough to have a global climate impact. The sad part is that fossil fuel emissions are rising by about 2% a year so even if we all could stop breathing in about two and half years our efforts would be eliminated.

While it is an interesting calculation it does not alter the fact that a reduction of 5% in emissions could easily be achieved by simple measures such as improving efficiency, nor does it alter the fact that the burning of fossil fuels is adding a massive unnatural load to the carbon cycle.