EPA document supports ~3% of atmospheric carbon dioxide is attributable to human sources

As has been pointed out innumerable times on WUWT and every other skeptic web site around, plants need CO2 to live and survive and to provide the carbon component from the splitting of the CO2 molecule in the photosynthetic process for the sugars they produce that provide the plants with the energy that allows them to grow, flower and set seed.
Without plants there would be no sentient life on this planet.
Again as has been pointed out innumerable times, the pre industrial atmospheric levels of CO2 are claimed to have been around 280 ppm.
Plant biologists looking at fossilised leaves and counting the stomata that are the pores on the underside of the leaves through which CO2 is taken in by the plant and O2 left after the splitting of the CO2 molecule for it’s carbon component, plus water vapour, is expelled through those same leaf stomata.
High CO2 concentrations mean that the plant needs fewer stomata to access it’s needs for that essential CO2. Fewer stomata also means the plant conserves water better leading to more growth but less water requirements per growth mass to achieve that extra growth.
Consequently plant biologists who have studied the stomata numbers in fossilised leaves have claimed that the pre-industrial CO2 was around the 310 -320 ppm, or 30 or 40 ppm above that long standing claim of 280 ppm of pre-industrial CO2.
But that 280 ppm claim does make the supposed anthropogenic / humanity contribution to atmospheric CO2 by raising the CO2 levels to 400 ppm seem a much greater contribution than is likely the case.
At around the 180 ppm level of CO2 a lot of plant species start to suffer severe slow downs in growth as they become starved for that essential CO2 to split for its carbon component to make those growth essential plant sugars.
Below 150 ppm of atmospheric CO2 some plant species die due to CO2 starvation..
So if we take 180 ppm as the minimum plant requirement for survival then at that pre-industrial level of CO2 of 280 or 300 PPM, the plant kingdom had a pre-industrial CO2 buffer of about 100 to 120 ppm over it’s minimum for survival 180 ppm CO2.
At 400 ppm of CO2 that CO2 buffer stretches out to 220 ppm
Effectively if the increase in plant essential CO2 to 400 ppm is accepted as anthropogenic in origin, we humans have doubled the amount of the available plant useable CO2 from it’s previous buffer of 100-120 ppm pre-industrial levels to a healthy for plants, 200-220 ppms today..
Plants have got to love us for that and as we sentient beings of every calibre are in fact utterly dependent on the plant kingdom for our very existence then that doubling of available and plant useable CO2 over the last 40 or 50 years is of immense benefit to ALL life on this planet.
And if there is a fraction of a degree warming included then that also is of very considerable benefit.
May it long continue although sadly the warmth part of the equation might be coming to an unfortunate end for the next few generations of mankind.

The Mauna Loa CO2 trend gives some clues as to how much of the increase in atmospheric CO2 is man-made.
http://www.esrl.noaa.gov/gmd/ccgg/trends/
Although atmospheric CO2 has increasing by 2 ppm each year for many years, every northern spring, CO2 concentrations actually fall by 7 ppm followed by a 9 ppm increase in the northern autumn. This cycle repeats every year without fail. Obviously seasonal changes in temperature are causing the seasonal fluctuations in atmospheric CO2. This raises two points:
1. Natural effects causes atmospheric CO2 to fluctuate hugely every year. Even if you accept that all the 2 ppm net annual increase each year is man-made, the natural annual fluctuations are much greater than the annual man-made effects. Without understanding the natural long term CO2 cycles, to assume that all the long term CO2 increase in the last 100 years is man-made should not be accepted as very likely at all.
2. The seasonal CO2 fluctuations clearly show that the temperature changes first, followed by changes in atmospheric CO2. Temperature is the independent variable and CO2 the dependent variable. This is the opposite of what the IPCC claims. Could someone among the many informed WUWT readers please explain how a dependent variable can also be an independent variable? I did not think that was mathematically possible.

At one Utah site CO2 varies by 150ppm between summer and winter.
http://co2.utah.edu/co2tutorial.php?site=7&id=1
Rotting vegetation probably explains the yearly variation … not fossil fuels.
So the cycle we are getting all excited about:
LIA recovery = more vegetation = more CO2 when it rots

“I don’t think this should disappear from WUWT”
Nor is it in any danger of doing so. Good time to ponder alarmist sites with their penchant for disappearing mistakes, and contrast that with most of the skeptic sites I know about. Who doesn’t make a mistake from time to time, especially on such a high volume site? Kudos Anthony.

Wow.
I’m really disappointed to see such misinformed “analysis” appear here, but I’m encouraged by the fact that so many commentators have promptly weighed in to correct the errors in understanding.

Anthony Watts says:
July 29, 2014 at 7:42 am
Anthony:
My kudos to you sir for responding to this error in an honest and open way that these days seems to be totally opposite of the way the CAGW alarmists react when they know that they’re wrong. It is refreshing to see and It serves to reinforce my belief that the truth about the CAGW issue does indeed lie here at your blog.
It is my belief that CAGW alarmists are totally off the mark if they think that they are morally and ethically right these days to engage in lies and the perverse manipulation of science to achieve what they feel is a just and righteous end. Among other things, history teaches us that it is technological advances and improvements that usher in new eras in human history. Thus it will be technological improvements and advancements that will someday usher in a post-fossil fuels world (probably a nuclear powered one among other things) and not CO2 taxes, cap-and-trade-schemes, solar and wind boondoggles, and scientifically bogus climate scare campaigns. A campaign built on lies is one built on quicksand.
Anthony, keep up the great work at this blog. You are worth your weight in gold. Let’s see…gold is around $1300 the ounce right now multiplied by……how much do you weigh Anthony?
REPLY: Thanks. I try not to be like John Cook – Anthony

“The level is now 400 ppm, the highest level for 800,000 years. In the absence of any other theories to the contrary, it is reasonable to suppose that the current enhanced CO2 levels are due to human activity.”
Huh? Every time I see a house fire I drive up and sure as hell the fire department is there, so I reasonably suppose that these fires are due to fire department activity.
The Vostok ice core graphs also show a major decline in temps over the holocene, with larger temperature swings as we get closer to present time. It also shows temperature rise preceding CO2 rise. It also shows a metric crap ton of temperature swings, all but ONE of which happened before industry showed up. So why would I be out of line to complain when CO2 attribution is used to artificially raise energy costs and reduce my standard of living? The climate “scare” started with the hippy/greeny anti SUV attitude and went on from there. Now it has morphed into a cosmic money and power grab. Need more science please, less MSM and IPCC.

Regarding the “right” level of CO2: obviously, there isn’t a per se “right” level. But we do have a planet’s worth of infrastructure that is based on certain assumptions we’ve made about rainfall, temperature, available water supplies and sea level. If those assumptions prove to be incorrect, we will have to do something about it: relocate cities, convert arable land to passive uses and vice versa, and on and on.