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CO2 - Friend or foe?

  1. Nov 11, 2003 #1
    Part of Explorations today dealt with CO2 emissions and the melting southern ice shelf. I have a colleague who argues against placing controls on CO2 emissions because, since CO2 is a naturally occurring gas, there is no way that it can be justifiably called 'harmful'. Since it is 'natural' and not 'harmful' there is no reason why it should be controlled.

    What do real scientists have to say about this reasoning methodology? Are there any other instances where too much of a natural thing can be harmful?

    I recall reading something discussing the changing balance between O2 and CO2 and the possible ramifications on life. Unanswered questions were raised as to what such a change in balance might mean on a biological level. Could this explain attention deficit disorder? IOW, could some of our societal problems lie in the air we breath?

    Thank you very much
  2. jcsd
  3. Nov 11, 2003 #2


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    There is a theory that the natural world can absorb even quite large variations in atmospheric CO2. It goes like this, if the CO2 builds up, plants will grow more vigorously (this has been demonstrated). So they will put out more roots and thus deepen the humus that covers the natural floor of the ground. And the deeper the humus , the more atmospheric CO2 it will absorb and fix for long periods of time. So you have a rough negative feedback loop here.

    Your friend's dichotomy of "natural" or "artificial" is not adequate in thinking about the world. Too much of something can be bad for you, even if it's natural and even if a little bit is good for you. Consider sugar. For that matter snake venom and anthrax are natural.
  4. Nov 11, 2003 #3


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    You should ask your friend if he would like to bathe in some perfectly natural H2S04 (Sulfuric Acid).

    CO2 is an interesting case because there are many different processes that emit CO2. There are geological processess that trap and release CO2 on a large scale. In fact, a currently popular theory calls for volcanoes to emit sufficient greenhouse gas and soot to end an ice age.

    This is AFAIK not an accepted theory, but it's entirely possible that highter CO2 levels lead to higher temperatures leading to more biomass leading to more carbon trapping at the bottom of the ocean leading to lower CO2. That would mean that the CO2 levels are more-or-less self balancing.

    Unlike other many other types of air polution, CO2 is also relatively easy to deal with because there are so many organisms that interact with it. For example, H2S, the chemical that causes rotten egg smell, is much more difficcult to deal with because it is much more toxic, and there are relatively few organisms that are adapted to dealing with large quantities of it.
  5. Sep 24, 2005 #4
    I think that the main problem is that the majority of the public don't understand the subject. Environmentalists seem happy for the public to draw the conclusion that mankind produces all of the Co2 and this is simply not the case and by a long way.
    Additionally, the majority greenhouse gas (approx 99%) is water vapour and no one has suggested limiting that!
    They also use ridiculous scaremongering statements such as, "We (humans) are destroying the planet". Someone should suggest that they consult a dictionary for a definition of the word destroy!
  6. Sep 24, 2005 #5
    His arguement is very poor. Suppose my Leukemia came back. Then one way to save my life is to give me chemo until all my white blood cells are dead. Then give me in the correct manner a thethal dose of radiation. After the radiation kills all the "blood cell" producing cells inside the bone marrow the patient is given healthy marrow from another, matching, patient. The marrow then gets nice and comfy in its new home and the patient is cured. So you tell me? Is that dose of radiation lethal?

    My motto in life is this - All things in the right amount

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