Is Increased Atmospheric CO2 Manmade
Posted by greg2213 on September 17, 2010
Naturally the luke-warm to catastrophic crowd says, “YES!” and tends to ridicule any thoughts to the contrary. That “settled Science” thing you know. If so many of them didn’t put Mr. Gore up on a pedestal as The Truth Giver then maybe it would be easier to go along with that “settled science.” Ridicule doesn’t tend to endear people to your argument, especially when all of Mr. Gore’s arguments are so very wrong.
Kinda like the climate sensitivity to CO2, which seems to shrink every decade or two. It was once 6C or so, now it’s around 1C or so. But that’s in a lab. In the real word one has to factor in known and unknown feedbacks into the sensitivity part, so the real number probably approaches zero.
Ok, fell off the track there…
Actually, given all the fuel burning industry of the world I’m perfectly willing to believe that some of the increase is man-made.
WUWT has an article discussion the isotope issue and why that points to a Yes answer.
The carbon of CO2 is composed of different isotopes. Most is of the lighter type: 12C, which has 6 protons and 6 neutrons in its nucleus. About 1.1% is the heavier 13C which has 6 protons and 7 neutrons in the nucleus. There also is a tiny amount of 14C which has 6 protons and 8 neutrons in the nucleus. 14C is continuously formed in the upper stratosphere from the collisions of nitrogen with cosmic rays particles. This type of carbon (also formed by above-ground atomic bomb experiments in the 1950′s) is radio-active and can be used to determine the age of fossils up to about 60,000 years.
The rest: Is it manmade?
The article is followed by the usual few hundred comments, from true believers to true skeptics.
Chiefio discusses isotope ratios here:
It is often asserted that we can measure the human contribution of CO2 to the air by looking at the ratio of C12 to C13. The theory is that plants absorb more C12 than C13 (by about 2%, not a big signature), so we can look at the air and know which came from plants and which came from volcanos and which came from fossil fuels, via us. Plants are ‘deficient’ in C13, and so, then, ought to be our fossil fuel derived CO2.
The implication is that since coal and oil were from plants, that “plant signature” means “human via fossil fuels”. But it just isn’t that simple. Take a look at the above chart. We are 5.5 and plants are putting 121.6 into the air each year (not counting ocean plants). There is a lot of carbon slopping back and forth between sinks and sources. Exactly how closely do we know the rate of soil evolution of CO2, for example?
The rest: The Trouble With C12 C13 Ratios
So we have CO2 from fossil fuels, forest fires, out gassing, vegetative respiration, bazillions of tons of microbes in the soil and the sea, animal respiration, and so on.
Of course, the next important question after proving the the CO2 increase is man-made, assuming that it is, is this: So what?
For a variety of reasons we should be looking to increase world CO2 levels, that much is clear from history. If CO2 does contribute some small amount to warming then perhaps it will help push away that next ice age, which really would be catastrophic.