For a tabloid quite a good summary of the debate and what ‘hide the decline’ refers to.
Read it here
Sunday, December 13, 2009
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8 comments:
I guess, I had been always a little suspitious of claims made by anthropogenic global warming supporters and recently I came out with a very simple math problem that, in my simplicity, has convinced me of the non-sense of assuming that present day GW (if it exist) is anthropogenic in origin.
It could be presented like this: given that (1) Human CO2 contribution to the atmosphere is around 3% (actually 2.91% from figures published in IPCC´s 2001 report), and that (2) CO2 maximal contribution to the green-house-effect is estimated to be 26% (Wikipedia: a non-skeptic-source for AGW), the actual maximal-man-made-contribution to global warming could be calculated to be: 0.03 x 0.26 x 100 = 0.75%. That means that less that 1% of any change in the climate attributed to CO2 could be blamed on humans. Which reasoning do AGW-supporters use to blame humankind for 100% of any CO2 linked climate change?.
It seems to me very unlikely that the actual annual increase of CO2 in the atmosphere (11,700 billion Tm; according to IPCC´s 2001 report), equivalent to 50% of our CO2 production, corresponds only to human produced CO2. In this respect, are there any atmospheric CO2 isotope studies supporting that Mother Nature selectively absorbs ONLY/MOSTLY human-produced-CO2 in the atmosphere?. If so, any references pointing to that possibility would be most appreciated.
I´m posting this question here to be corrected if I´m wrong, but also to show my appreciation for this blog, and to show my respects for what I feel the scientific integrity of its contributors.
Best regards. Alfonso
you are wrong. Totally. Did you ask the same question at realclimate.org, too?
It is assumed the CO2 part in the atmosphere was approx. 280 ppm at the beginning of the industrial revolution. Now it is ca. 390ppm. Thus, our contribution is much higher than 3%, around 30%.
Now, how can we know this?
the isotope ratio is changing. it is known plants like C12 carbon more than C13/C14. Therefore, fossils fuels do not contain C13 or C14. Thus, there is an observed lowering of the C13/C12 ratio in the atmosphere. The same for the oxygen: the oxygen part of the atmosphere is decreasing, fitting exactly to the burned carbon mass.
Additional evidence is the acidification of the oceans and the increase CO2 content in the oceans. That means, oceans are a sink, not a source.
Secondly: the net effect matters, if more CO2 is emitted to the atmosphere than absorbed, the CO2 concentration will increase. And we add the additional amount of CO2.
All this has been proved for a long time. And the measurements are repeated and repeated.
There are still uncertainties in the carbon cycle, but it is definite that we humans are responsible for the CO2 increase.
There are many more evidences and measurements, that I do not know, I am not a scientist.
My question now: what do you think about the anthropogenic global warming now?
Dear Alfonso, dear anonymous,
It is not that simple to detect the anthropogenic CO2 origin in the atmosphere, anonymous is not right on this.
A very good dicsussion of this subject s provided by Roy Spencer:
http://www.drroyspencer.com/2009/01/increasing-atmospheric-co2-manmade%E2%80%A6or-natural/
Corinna
The oceanic carbon content change is actually not very well known, we are lacking specificaly measurements from pre-industrial time and estimations of deep ocean carbon contents. The atmospheric CO2 is particularly sensitive to variations of the mineralisation depth and hence the distribution of carbon content between upper and deeper ocean. Minor changes in the remineralisation depth could have pronounced impacts on atmospheric CO2 concentrations.
A recent paper by Kwon et al. discussed these impacts:
EY Kwon, F. Primeau, JL Sarmiento (2009). The impact of remineralization depth on the air-sea carbon balance. nature geoscience, DOI:10.1038./NGE0612.
Kwon et al. found that an increase of 24m in remineralisation depth will result in a decrease of atmospheric carbon content by 10-27 ppm in their model. Natural variations in remineralization depths are certainly larger than those tested.
To add: remineralization is a.o. temperature and oxygen dependent and hence likely to be influenced by warming of the ocean (also by solar warming).
By the way, Roy Spencer made also an interesting presentation at the AGU meeting,
http://wattsupwiththat.com/2009/12/17/spencer-on-his-agu-presentation-yesterday/
@Corinna
Thanks a lot for the links. I will read them (if I post as anonymous is because it is the only way I can get to post).
Thanks again
Alfonso
@the non-Alfonso-Anonymous
First, yes I was the one asking at realclimate (you see I'm trying to solve my doubts, by asking questions).
One thing that I may have learnt (I hope) since I made the previous post is that 13C is low both in fossil fuels and living plant fuels.
http://www.bgc.mpg.de/service/iso_gas_lab/publications/PG_WB_IJMS.pdf
if my statement is correct, I do not think that a decrease in atmospheric 13C-CO2 can be taken as proof that increased atmospheric CO2 concentrations are the result of fossil-fuel-burning, for an increase in respiration by present day plants could theoretically lead to a similar decrease in atmospheric 13C-CO2.
With respect to your statement "The same for the oxygen: the oxygen part of the atmosphere is decreasing, fitting exactly to the burned carbon mass", I have no data to argue (either way), but I would appreciate you send me a link to a reference for learning more about it (thank you).
I agree with you that, if I understand it correctly, acidification and the increased CO2 content in the oceans means they act as sinks. However, oceans will become more acidic (at a given temperature) irrespectively of CO2 origin (natural or anthropogenic) as long as an increase in CO2 concentration takes place. Therefore (IMHO) ocean's acidification "per se", while fitting our present paradigme, is not proof that fossil-burning by humans is its major cause. To make it clear: we are certainly contributing to it, but the question is: to which extent?.
With respect to your final question "what do you think about the anthropogenic global warming now?", I tell you that I still do not have a clue if it is majorly (or minorly) anthropogenic in origin, but I will make my own mind about it if I'm able to read (and understand) the original sources. Xmas season is coming by, and it may be fun to make some reading (Corinna´s links look interesting).
Best regards
Alfonso
hello Alfonso, Corinna
i have a really nice link about CO2 and Dr Roy Spencer:
http://www.drroyspencer.com/2009/01/the-origin-of-increasing-atmospheric-co2-a-response-from-ferdinand-engelbeen/
As Corinna knew the first article, she must have known also the second, but she did not mention it... hm. I knew both, therefore I did not mention them.
Yes, it is true, C13 depletion is coming from vegetation and fossil fuel. Assuming: vegetation is increasing because of global warming and more CO2, the C13/C12 ratio has to increase not decrease. IMHO, AND you must say, vegetation is increasing, if you do not accept the ocean as sink. Maybe there is a further big sink...
oh, the data, I am a layman, I learned a lot from Ferdinand Engelbeen: http://www.ferdinand-engelbeen.be/klimaat/co2_measurements.html, he collected many information about this issue. In my opinion, this site is a good starter in this issue.
As you can see, Ferdinand is talking with Dr Spencer and he is skeptical about the influence of CO2 as greenhouse gas. That makes him even more convincing in my eyes.
At last, something more about Dr. Spencers CO2 discussion: http://tamino.wordpress.com/2009/01/19/a-bag-of-hammers/ (from tamino).
IMHO, Dr Spencer is wrong and the Keelings, Suess, Revelle, etc are right.
Best regards,
ghost the anonymous
@Alfonso
one more nice link: if you want to read more about the issues and the history, Spencer Weart is another great source: e.g., http://www.aip.org/history/climate/Revelle.htm
on this site, you can discover a lot about the history of "greenhouse" research. At least it is one nice starting point.
Hope it helps.
last post.
@Corinna
your reference to Kwon et al is a little bit, hm, strange. At first, they said, there is no change in the remineralization depth at the moment, second, does this change the C13/C12 ratio, the Oxygen ratio etc? Fact is, we emit twice as much as the CO2 increase in every year. Thus, something has to absorb the other half. Is it only the biosphere, there must be another O2 signal. If the oceans are sources, there cannot be the observed C13/C12 decrease. No, no, no, there are many open questions about the carbon cycle, but it is quite clear, we are responsible for almost all additional CO2 in the atmosphere.
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