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Thread: 3 simple facts about CO2

  1. #1 3 simple facts about CO2 
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    Just in time to be too late for inclusion in an earlier discussion, this neat summary of CO2 facts turned up today.

    Introductory remarks
    Some things about carbon dioxide in the climate system are so firmly established and fundamentally important, you can use them as litmus tests to determine whether the person you are listening to is honest and knowledgeable. Note that somebody contradicting these facts may be dishonest or ignorant or both, but itís usually not possible to tell which.

    Fact #1: A small concentration of CO2 is a big deal...... ...... ....

    If you hear or read somewhere that the amount of carbon dioxide in the atmosphere is so small that it must be unimportant, your source is either too naive to know better or trying to deceive you.

    Fact #2: The fraction of CO2 molecules in the atmosphere that were produced by man is different from the fraction of CO2 molecules in the atmosphere that are there because of man.
    ..... .... ....

    If you hear or read somewhere that the amount of man-produced CO2 in the atmosphere is only a small fraction of the total CO2 in the atmosphere and that therefore man is having a small effect, your source is either too naive to know better or trying to deceive you.

    Fact #3: Carbon dioxide is good for plants, in the sense that it makes them grow more rapidly.
    .... ...... ....

    ... we see that plants as a whole are certainly benefiting from climate change, in the sense that they are extracting more carbon from the atmosphere and turning it into plant material than before.
    If you hear or read somewhere that manís addition of CO2 to the atmosphere has been generally harmful to plant productivity, your source is either too naive to know better or trying to deceive you.

    The whole item appears here if you want to read the full details rather than the abbreviated text I've shown. Three Simple Facts About Carbon Dioxide | Climate Abyss | a Chron.com blog
    (One special note. John Nielsen-Gammon is totally opposed to the term, greenhouse gases, because of its known descriptive inaccuracy. Rather than go wth the flow like everyone else and accept that it's become the standard nomenclature, he insists that CO2 and its friends shoudl be called Tyndall gases. I also suspect he wants to raise the profile of the earliest climate science contributors.)

    The only issue I would raise is with his far too vague description of "plants as a whole" benefiting from increased CO2. John N-G is a meteorologist and he's the Texas State Climatologist. He's a reliable expert on analysing and predicting droughts, storms, seasonal outlooks and the like, he's not an expert on agriculture or ecology. Those experts argue that it's not much good to us if the plants that benefit from increased CO2 are things that either we can't eat at all or are weeds that damage crops of items we do eat.

    The agriculture folks also point out that warming by greenhouse gases (rather than other warming mechanisms) increases night-time temperatures more than day-time maxima - and many cropping plants have a cut-off point where they won't set seed at higher overnight temperature. Rice and corn are already showing problems of this kind in a few areas. It won't matter to us if crops grow faster or bigger if they won't set seed that we either eat directly or need for planting the next crop.


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    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  3. #2  
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    This space is reserved for climate change deniers to spout inane nonsense in response to the above.

    Another service brought to you by the "John Galt for World Dictator" campaign.


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    It's possible that for many plants CO2 is a limiting resource - but the matter is very complicated, and the results of boosting CO2 would have to be played out over several generations and several regular weather cycles to answer.

    One of the central compexities is the timing and duration of stomatal opening - if a plant would have to open its leaf pores more at the wrong times than is strictly good for it, to exchange gases at the optimal rate for its maximum employment of CO2 (would lose water that is hard to come by, etc), then simply supplying more CO2 per minute of pore opening would benefit that plant. But for a plant that has already maxed its CO2 usage capability and is depending on its pore opening triggers to get rid of O2 or cool by evaporation or the like, extra CO2 might actually interfere with its pore triggers and best functioning.

    Meanwhile, even if all plants in a location do better on higher CO2, some will benefit more than others - in Minnsota, where cold and dry conditions have influence and the sunlight regime booms and busts seasonally, poison ivy appears to be much benefited by higher CO2, C4 grasses less benefited; this may explain why along the woodland edges of many meadows poison ivy is spreading into grassland where it was formerly unable to compete.

    CO2 is a nutrient. Each species of plant has an ideal or best function relative rate of supply of all its nutrients, so much nitrogen per minute vs so much potassium per minute for example (in any given situation,), and its own sensitivity to changes in those relative rates, as well as its maximum efficiency of use (how far it can draw a given nutrient down in the soil, how low a rate of supply it can handle, for example). At any given moment only one or two of those nutrients will be limiting, and boosting the others doesn't generally help much or have direct and easily predictable effects.
    Last edited by iceaura; February 10th, 2012 at 02:12 PM.
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  5. #4  
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    Quote Originally Posted by adelady View Post
    Just in time to be too late for inclusion in an earlier discussion, this neat summary of CO2 facts turned up today.

    Introductory remarks
    Some things about carbon dioxide in the climate system are so firmly established and fundamentally important, you can use them as litmus tests to determine whether the person you are listening to is honest and knowledgeable. Note that somebody contradicting these facts may be dishonest or ignorant or both, but it’s usually not possible to tell which.

    Fact #1: A small concentration of CO2 is a big deal...... ...... ....

    If you hear or read somewhere that the amount of carbon dioxide in the atmosphere is so small that it must be unimportant, your source is either too naive to know better or trying to deceive you.

    Fact #2: The fraction of CO2 molecules in the atmosphere that were produced by man is different from the fraction of CO2 molecules in the atmosphere that are there because of man.
    ..... .... ....

    If you hear or read somewhere that the amount of man-produced CO2 in the atmosphere is only a small fraction of the total CO2 in the atmosphere and that therefore man is having a small effect, your source is either too naive to know better or trying to deceive you.

    Fact #3: Carbon dioxide is good for plants, in the sense that it makes them grow more rapidly.
    .... ...... ....

    ... we see that plants as a whole are certainly benefiting from climate change, in the sense that they are extracting more carbon from the atmosphere and turning it into plant material than before.
    If you hear or read somewhere that man’s addition of CO2 to the atmosphere has been generally harmful to plant productivity, your source is either too naive to know better or trying to deceive you.

    ...
    Not that I'm disagreeing with you but your first two points need some quantification. Just how small an amount of CO2 is an issue? Just how is man produced CO2 differnet from natural CO2? The last seems particularly counter intuitive.
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    From the link .........

    Relatively few of the CO2 molecules emitted by the burning of fossil fuels remain in the atmosphere. Most have been taken up by plants or absorbed in the ocean.
    But for every two man-produced molecules of CO2 that have been taken up by plants or absorbed in the ocean, there’s one molecule of natural CO2 that would have been taken up or absorbed, except that its place was filled by a man-produced molecule of CO2. So it’s been effectively squeezed out into the atmosphere.
    Infrared radiation doesn’t care whether the molecule it encounters is natural CO2 or man-produced CO2. So the key parameter is the total man-caused change in atmospheric CO2 concentrations, not just the concentration of man-produced CO2 molecules in the atmosphere. And yes, almost all of the rise in atmospheric CO2 concentrations since pre-industrial times has been caused by man.
    The difference between emitted CO2 molecules and those that are part of the 'natural' carbon cycle? Simple. Carbon isotopes.

    ....... "CO2 produced from burning fossil fuels or burning forests has quite a different isotopic composition from CO2 in the atmosphere. This is because plants have a preference for the lighter isotopes (12C vs. 13C); thus they have lower 13C/12C ratios. Since fossil fuels are ultimately derived from ancient plants, plants and fossil fuels all have roughly the same 13C/12C ratio – about 2% lower than that of the atmosphere. As CO2 from these materials is released into, and mixes with, the atmosphere, the average 13C/12C ratio of the atmosphere decreases. "
    4th paragraph of this item .... RealClimate: How do we know that recent CO2 increases are due to human activities?

    There are a lot of papers on this if you want to follow up further.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  7. #6  
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    Quote Originally Posted by adelady View Post
    Fact #3: Carbon dioxide is good for plants, in the sense that it makes them grow more rapidly.
    ...
    If you hear or read somewhere that man’s addition of CO2 to the atmosphere has been generally harmful to plant productivity, your source is either too naive to know better or trying to deceive you.
    That concluding sentence doesn't seem to make sense in the context of the article. Just before that it says, "A common skeptic argument is that CO2 is good for plants."

    So, surely, that concluding paragraph should be more along the lines of, "If you hear or read somewhere that man’s addition of CO2 to the atmosphere is universally good for plant productivity..." ?

    And of course, that isn't true. Increased CO2 is good for some plants under some situations. But, for example, the combination of increased temperature and increased CO2 (which seem to go hand in hand) is potentially devastating for rice production in many parts of Asia.
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  8. #7  
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    Yeah. This seems to be one of John's blind spots.

    You're not the first to notice this and others have made similar points to him at various times. He responds by criticising what he calls "the stupid farmer" model. The argument being that farmers aren't silly and they won't just let their crops die (though I don't see they've got much option in a drought or a flood) but they'll move to different strains or to different crops entirely.

    I don't buy this. It's one thing for farmers to move to better strains or species to improve production. It's another thing entirely to find yourself on a Red Queen's racetrack - running like hell to stay in the same place. It's already costing some Australian grape growers bulk money to graft new varieties onto existing plants to cope with shorter seasons and higher temperatures. Or replanting entirely for the rootstocks to cope with different rainfall patterns. And that's just for wine. How this scenario works for essential food production by poor rice/maize/cassava farmers in tropical countries I hate to think.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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