Are the ice core CO2 measurements accurate? (Part Two)?

Question

Other methods of reconstructing past CO2 concentrations in the atmosphere show more variation in the CO2 levels than the ice cores. For example, plants have minute pores in the epidermis of the leaf or stem through which gases and water vapor pass. The density of the pores varies with the level of carbon dioxide in the atmosphere. This has been tested in controlled environments in which the CO2 is held at a constant level and the pores developed at a density adequate enough to take in the required amount. If CO2 is increased, fewer pores are required. If CO2 is decreased more pores develop.
The stoma pores can be seen in fossilized leaves and CO2 concentrations can be determined from past climates by their density and carbon dating of the fossils. A study was done that reveals CO2 varies much more in the plant record than in the ice cores. It showed CO2 levels during the Holocene maximum to be as high as 328ppm.

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=129389

In actual chemical measurements taken by chemists and engineers from around the world and averaged, the CO2 levels varied more than the ice cores and have been comparable to present day levels.

http://www.anenglishmanscastle.com/180_years_accurate_Co2_Chemical_Methods.pdf

I’ve seen the so called “debunking” on RealClimate.com Driving around in Paris measuring CO2 concentrations today as compared to 1820 is apples & oranges.

Bob,
"Do you seriously think CO2 levels have jumped around like that in the last 180 years?"

Not at Mauna Loa.

Answer 1

You can't put a carbon monoxide detector at the tailpipe of your car and expect the reading to have any relationship to global values. And for exactly the same reason, you can't measure CO2 in an industrial region and expect it to have any relationship to global values, either.

Nearly all of those early 19th century readings (as described in your link) were taken in Europe. Well that's fine, but Europe was and continues to be one of the largest sources for CO2 emissions on the planet. So what are we really learning from that? Not much.

That's why today we take CO2 readings from the most remote areas we can find, like the top of a mountain in the middle of the Pacific Ocean, or Antarctica. These are properly described as the amount of "background" CO2, that is, the amount of CO2 in the air not associated with nearby CO2 sources. You can't expect CO2 measurements in industrial areas to be comparable, and they're not.

Answer 2

Becks article is not a reliable source for information about CO2 levels. It is an interestign read, but it is poorly written and the conclusions drawn can be rather easily refuted.

I will say this in defense of the scientists that made the measurements in the past:

I think the numbers are accurate due to the fact that the chemical methods for CO2 determination are well established and well refined. However, sampling is likely the problem, in that there can be significant local variations in gas concentrations. A simple analogy is the air temp in the shade vs full sun. By moving a few feet you get a different temp value. If there was some sort of CO2 source nearby (an early industrial age smoke belching coal plant) that would account for localized high CO2 concentrations. Thus the measurements are good, the samples are likely bad.

Answer 3

This isn't my area of expertise, you need a botanist or ideally, a paleobotanist, to provide a detailed answer.

What I do know is that the botanical record based on stomata is is highly variable and inconsistent. The same experiments conducted twice on the same sample produce varied results and if the experiment is repeated with different samples from different locations there are major discrepancies in the ppmv measurements.

If you look at the graphs in your second link and compare them you'll find there are broad inconsistencies with results fluctuating by as much as 25%, this compares with less than 0.2% for the ice core record.

You'll also see from the graphs that the CO2 levels according to these methods are all over the place and there are variations of up to 120ppmv in a single decade.

Further, compare the reconstructed readings with the actual ones and then have a look at the ice core readings. The instrumental record is remarkably consistent and shows a steady rise in CO2 levles that follows a gentle upward curve.

Now have a look at the botanical / chemical record. This doesn't begin to follow such a pattern and at best provides a rough (to within 25%) estimate of levels of atmopsheric carbon dioxide.

Now look at the ice core record and compare this to the instrumental observations - for all intents and purposes it's impossible to distinguish one from the other.

In short, the ice core record replicates what we're actually observing, the botanical record doesn't.

Answer 4

This question shows two things clearly.

The stomata data shows that his is a less accurate measurement than ice cores. Even so, 328 during the Holocene (unlikely) hardly affects the significance of the current data.

The "180 years" article simply shows that there's a lot of old bad data out there. Do you seriously think CO2 levels have jumped around like that in the last 180 years? And suddenly smoothed out when we started making good measurements? Figure 2, and repeated in figure 9.

Absurd doesn't begin to describe that idea. The CO2 residence time in the atmosphere is many years. It's completely physically impossible to jerk that number around so rapidly. The amount of CO2 you'd have to input and, even less likely, remove, in a very short time, is astronomical.

This question (and especially figure 9 in the 180 years article) is basically excellent support for the accuracy of the ice core data.

EDIT - Forget Mauna Loa. I guess I didn't say it clearly enough. It's PHYSICALLY IMPOSSIBLE for CO2 levels to jump around like that, worldwide. Especially going down. Not unless the Almighty has a CO2 specific vacuum cleaner to suck CO2 out at an incredible rate, far in excess of any natural "sinks".

Answer 5

co2 is just 0.02% in air so if u ad 100% it wil com2 0.04%, f u ad 200% 't wil com 2 total 0.06%, f u ad 400% then 't wil com2 0.1% or air ! ! ! nw u decid urslf! is it possible for u to add400% cO2 in air even if u brn al patralium or forast ?