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Originally Posted by Cato
For the past ten years. Even if your argument weren't logically flawed, so what? What would this knowledge add to the debate?
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1) That co2 levels are rising. If co2 levels were not rising, they couldn't be a candidate for the recent warming.
2) That the co2 rise is anthropogenic.
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What evidence is that? What are all the natural causes for CO2 concentration fluctuations?
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Mainly temperature change. Ice cores show that co2 starts rising when temperature rises, and also show that during the little ice age co2 levels dropped about 10ppm. The basis of this is that the efficiency of processes like ocean absorption of co2 are dependant on temperature.
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No, they won't, according to your logic. You wrote:
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300 years ago nature was emitting as much as it absorbed.
As human activity started emitting more co2, nature started absorbing more in response.
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Which is true
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You reiterated this several times:
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The reason nature is absorbing more co2 than it is emitting is because there is an abundance of co2 in the atmosphere at this time.
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(Which has its own logical fallacy, but we'll stick to the current one.)
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I don't see how that can be seen as a logical fallacy. The equillibrium level of co2 in the atmosphere is largely a product of temperature. At this current time the level of co2 in the atmosphere is far greater than the level at which temperature can maintain it. All things equal co2 should be filtering out of the atmosphere in current conditions. It's only human contribution of an extra 28 billion tons co2 per year that is keeping the co2 rising.
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Ergo, if there were no human activity, CO2 levels would remain level at 280ppm. Do you believe CO2 levels would be at appr. 280ppm today if there were no human emissions?
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Yes
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How can co2 in the atmosphere continue rising if human emissions stopped, when nature is absorbing more than it emits?
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How can nature absorb more than it emits if you've already asserted the only reason it's absorbing more in the first place is because humans are emitting CO2?
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I am talking about if humans stopped emitting today. In that case there is still an abundance of co2 in the atmosphere and levels will start falling. I am not talking about if humans didn't emit in the first place. In that case co2 levels would most likely have remained near the preindustrial level of 280ppm to this day.
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Are you familiar with post hoc, ergo propter hoc arguments? Let me give you an example:
Everytime I walk out of the house with an umbrella it's raining. Can I therefore conclude my umbrella causes it to rain?
Correlation does not prove causation.
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We know umbrellas don't cause rain, there's no mechanism for them to do so. But we know that co2 emissions can cause co2 rises. "correlation does not prove causation" is a popular phrase but in reality when it is also coupled with mechanism, correlation can have a statisitical fit beyond chance, so becomes excellent evidence.
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How so? Does CO2 absorption always increase when there's an abundance of CO2 in the atmosphere? If so, then that either indicates: 1) an eventual reduction to 0ppm of CO2
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0ppm would be a shortage. There is a level of equilibrium which is largely determined by temperature (about 280ppm over the last few hundred years). If co2 levels are above this equillibrium level then absorption tends to outweigh emission, if they are below the level then the opposite is true.
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You want to presume since Man is here and emitting CO2 that somehow all the other natural causes of fluctuating CO2 concentrations stop.
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Quite the contrary. The fact is that natural causes of fluctuating co2 concentrations haven't stopped. At the moment nature is absorbing more co2 than it emits, so left alone nature would be pulling co2 from the atmosphere causing levels to drop. Ie rising levels at this time are not natural. It is the human source which is enough to mean more co2 is entering than leaving the atmosphere.
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Since Man is here, and CO2 concentrations have risen, Man has caused CO2 concentrations to increase. Post hoc, ergo propter hoc.
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That's not the argument. It would be better phrased as:
co2 concentrations rise due to more co2 being emitted into the atmosphere than is absorbed. Since man is here, extra co2 is being emitted into the atmosphere. Because co2 levels are only rising about half the rate man is emitting co2, nature must be a net sink of co2. Ie man is emitting twice as much co2 as co2 levels are rising. Therefore man has caused co2 concentrations to rise.
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But in no way is co2 going to continue rising without human emissions.
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Because CO2 doesn't rise naturally?
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No, because nature is absorbing more co2 than it is emitting. Take 2006 as an example - over that year nature took more co2 out of the atmosphere than it put in. Therefore without humans emissions you cannot have co2 levels rising in 2006. How could that possibly not be true?
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Assuming your numbers are correct. But quick assumptions really are the life-blood of this debate, aren't they?
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They are correct.
http://cdiac.ornl.gov/ftp/trends/co2/maunaloa.co2
http://cdiac.ornl.gov/ftp/ndp030/global.1751_2003.ems
What do you think would happen to atmospheric co2 levels if human emissions stopped tommorow? Don't you agree there would be 28 billion tons less co2
going into the atmosphere each year? Don't you agree that would turn the ~15 billion tons rise in atmospheric co2 levels each year into a 13 billion ton loss? I can't see how you could claim otherwise. mathematically it is impossible to subtract a larger number from a smaller number and remain with a number above zero.
The evidence is beyond doubt that co2 is rising, and the the rise is human caused.
Why does atmospheric CO2 rise