Arguments
How do human CO2 emissions compare to natural CO2 emissions?
What the science says...
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Basic
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The natural cycle adds and removes CO2 to keep a balance; humans add extra CO2 without removing any. |
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Climate Myth...
Human CO2 is a tiny % of CO2 emissions
“The oceans contain 37,400 billion tons (GT) of suspended carbon, land biomass has 2000-3000 GT. The atpmosphere contains 720 billion tons of CO2 and humans contribute only 6 GT additional load on this balance. The oceans, land and atpmosphere exchange CO2 continuously so the additional load by humans is incredibly small. A small shift in the balance between oceans and air would cause a CO2 much more severe rise than anything we could produce.” (Jeff Id)
Before the industrial revolution, the CO2 content in the air remained quite steady for thousands of years. Natural CO2 is not static, however. It is generated by natural processes, and absorbed by others.
As you can see in Figure 1, natural land and ocean carbon remains roughly in balance and have done so for a long time – and we know this because we can measure historic levels of CO2 in the atmosphere both directly (in ice cores) and indirectly (through proxies).
Figure 1: Global carbon cycle. Numbers represent flux of carbon dioxide in gigatons (Source: Figure 7.3, IPCC AR4).
But consider what happens when more CO2 is released from outside of the natural carbon cycle – by burning fossil fuels. Although our output of 29 gigatons of CO2 is tiny compared to the 750 gigatons moving through the carbon cycle each year, it adds up because the land and ocean cannot absorb all of the extra CO2. About 60% of this additional CO2 is absorbed. The rest remains in the atmosphere, and as a consequence, atmospheric CO2 is at its highest level in 15 to 20 million years (Tripati et al. 2009). (A natural change of 100ppm normally takes 5,000 to 20,000 years. The recent increase of 100ppm has taken just 120 years). [Paragraph updated July 2022, to correct information on % of additional CO2 that is absorbed.]
Human CO2 emissions upset the natural balance of the carbon cycle. Man-made CO2 in the atmosphere has increased by a third since the pre-industrial era, creating an artificial forcing of global temperatures which is warming the planet. While fossil-fuel derived CO2 is a very small component of the global carbon cycle, the extra CO2 is cumulative because the natural carbon exchange cannot absorb all the additional CO2.
The level of atmospheric CO2 is building up, the additional CO2 is being produced by burning fossil fuels, and that build up is accelerating.
Basic rebuttal written by GPWayne
Update July 2015:
Here is the relevant lecture-video from Denial101x - Making Sense of Climate Science Denial
Last updated on 5 July 2015 by gpwayne. View Archives
bullsh*tbullet.[DB] Per SkS contributor Gary McGuigan, here is another interesting example of how trace concentrations can have a large effect:
The Brazilian Wandering Spider (Phoneutria) or banana spider appears in the Guinness Book of World Records 2007 for the most venomous spider and is the spider responsible for most human deaths. This spider is believed to have the most potent neurotoxic venom of any living spider. Only 0.006mg (0.00000021oz) is sufficient to kill a mouse.
I have a question, is there any way of reducing some of the CO2 natural emissions or making other ways to absorve more CO2 preventing it from going to the atmosphere, such as planting more threes or something like that?
My question is, the only way to stop globar warming is reducing the human CO2 emissions?
(sorry for my english)
Juanss, due to albedo changes, replacing the world's agricultural areas with trees will not necessarily be of any aid in stopping global warming. Scientist Ken Caldeira has shown that replanting all available boreal forests and even mid-latitude temperate forests will lead to warming.
Only replanting all tropical areas with trees produces cooling. And there simply isn't enough of it to be effective (an area greater than the surface area of the United States must be replanted and no such sizable area exists). Only a drastic reduction in CO2 emissions will have any effects.
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Following on from what Daniel wrote, it is worth adding that it would be a good idea to try and limit further deforrestation of the tropics, for many reasons, including CO2!
There have also been attempts at seeding the oceans with nutrients to try and increase uptake by marine biota, but it didn't seem to help much. The link below discusses a chance experiment following volcanic activity, but I seem to recall this type of seeding being tried deliberately as well.
http://www.scientificamerican.com/article.cfm?id=seeding-atlantic-ocean-with-volcanic-iron-did-little-to-lower-co2
At the end of the day, cutting down fossil fuel use is likely to be easier and cheaper for the forseable future.
So how does this work? Do the natural cycles segregate man made CO2 from the natural produced CO2? It is true that nature balances the levels when there are changes in CO2 production, whether it's man made or natural. "Balance" is a variable and it is relative over time. When the CO2 levels increase, the amount of flora increases as well. It's so basic I don't know how you can write such things about non-issues.
Elysium, if you want to discuss science, then I would avoid starting your message "So how does this work?" and ending "It's so basic I don't know how you can write such things about non-issues.", which rather sounds like you have made up your mind about how it works.
If you think something is a non-issue, then state exactly what you think is a non-issue and why, and maybe someone will discuss it with you.
It clearly isn't "true that nature balances the levels when there are changes in CO2 production, whether its man made or natural". If it were, CO2 levels would not have been rising sharply for the last century or so.
Elysium... If you believe it's "so basic" then you should have no problem citing the published literature that supports the point you're trying to make.
I would first suggest that you read the comments policy before continuing the conversation.
I am in search of an answer that I have not found in the comments tread or searching other references...relating to the isotope ratio signature that identifies ACO2 emissions. Is there also the signature of O18? The isotope signature that identifies Oxygen combustion either from natural events such as wild-fires or or anthropogenic events such as fuel combustion.
What I want to know is if there is any signature that has O18 along with a C13-C12 ratio that would show combustion of older Carbon sources. It would appear to this layman that a signature directly related to the combustion of older Carbon would surely be the smoking gun of anthropogenic activity; not that any logical suspision really exist but another brick in the wall surely would be welcome.