Why is less than 0.04% CO2 important to climate change?

Discussion in 'Earth Science' started by Woody1, Jun 12, 2017.

  1. Woody1 Registered Senior Member

    I guess that means you don't think the internet has changed the way people do business in any significant way. That couldn't be right. You must mean something else.
    Last edited: Jun 13, 2017
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  3. spidergoat Valued Senior Member

    Even a "changing" business model is still business as usual. It's all predicated on relatively cheap energy.
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  5. exchemist Valued Senior Member

    Yes, I admit I had my tongue in my cheek when I wrote that.....

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  7. iceaura Valued Senior Member

    It was 280 or less, depending on your chosen start date of the industrial revolution.
    And there will be life on the planet (probably) even if AGW destroys human civilization as we know it over the next three hundred years - which is not likely, but is in fact possible. Increasingly possible.
    That's one of the risks "we" are choosing to take, in order to avoid the trouble and expense of cutting back on fossil fuel burning.
    Yeah, we do. Essentially: Every researcher who has published on the topic.
    I'm not sure what your question is. Are you asking why the entire planet is not instantly heating to its equilibrium temperature upon each new hike in the CO2? Or are you asking why a given concentration of CO2 might have different effects, depending on things like oxygen partial pressure and the like that were different then?
    It's all caused by the CO2 boost, essentially - the other gasses wouldn't matter without it;
    we control all of the CO2 boost;
    we don't know for sure how bad a disaster it will be - estimates range from "pretty bad" to "catastrophic".
    So why don't you?
    Why haven't your suspicions led you to observing relevant facts?
  8. billvon Valued Senior Member

    Good quote. And fortunately for science, the predictions made by IPCC models are coming true.
  9. exchemist Valued Senior Member

    If you were an educated person living in Bangladesh or the Netherlands, you would not be talking like that. If you do not understand why I say this, I am willing to explain it - and to explain why the fate of people in Bangladesh is important to the rest of us.
  10. Facial Valued Senior Member

    I have the impression that Woody1 is making a genuine effort to understand the science. I'll address the OP directly:

    A 270ppm to 400ppm CO2 concentration is important because of several reasons.

    1. CO2 has a long "residence time" meaning that it takes a long time (~5 years) for a molecule of CO2 to be absorbed back into the a solid or gas, or more generally rendering it in a state where it cannot absorb heat radiation. A spike in the concentration of CO2 will take hundreds of years to return to normal. Water vapor is different, because it doesn't stay in the atmosphere for as long. Pointers: The molecular ~5yr estimate can be traced back to Craig (1957) or earlier. Global climate models (GCMs) started around that time, maturing with enough power by the mid-80s by Hansen's work to predict our current situation. It is through these GCMs, also with ocean-atmosphere interaction work by Revelle and Suess (1957), that people now know the collective residence time of CO2 in the atmosphere.

    2. The unique infrared absorption bands of CO2 relative to water vapor, the dominant greenhouse gas, means that CO2 will always absorb IR at any increased concentration and never saturates out. Millions of these absorption lines are now known, and this information is stored in Harvard's HITRAN database, which I think is accessible to the public. The "golden age" of this spectroscopy was around the 1950's when heat-seeking missiles were developed by the U.S. military. A few physicists - Plass (1956, 1958), Manabe and Wetherald (1975) used them for climate computations.

    3. The energy gained by the earth from the extra IR absorption is only 1-2 W/m^2, which is small compared to net 300-400 W/m^2 on a sunny day. But that really does add up over the years and one can't expect nothing to happen over decades. The effects on weather, which is more unpredictable than climate, is the emergent development of more extremes. There's a good paper on this topic by Hansen et al. (2012). This happens all the time across many different areas of science including my own past research on engineering. A statistician would call this "heteroscedasticity," and a statistical physicist would draw analogy to the Boltzmann distribution for molecular velocities in a heated gas.

    I know there are many, many references for each of the three points made above, but sometimes it's hard to find simple facts in the academic literature even from Google Scholar. In my opinion, the IPCC summarizes the science very well. For more technical information, it's probably best to consult someone working on the topic. Just keep looking and be persistent.

    Link to a good video on the topic. (I've met this guy before).
    Last edited: Sep 2, 2017
  11. river Valued Senior Member


    I'm with you.

    People just understand what the mainstream media gives them .
  12. iceaura Valued Senior Member

    Woody's one of those people. The trouble comes from the refusal of guys like Woody to learn better - he actually defends his media-inculcated state of confusion and ignorance, by rejecting information that would straighten him out.
    That rejection too is something he got from the mainstream media, and it's politically motivated as well as organized by the agenda of the corporate influences on the corporate media we label "mainstream".
    That's why the Republican Congress and Republican White House is jacking around with the primary sources of information, such as the scientists doing the relevant research - what we saw under W&Cheney, with political operatives assigned to all Federal research agencies and all communication with the public channeled through them rather than coming directly from the researchers involved, is becoming even worse under Trump; the researchers themselves are being moved, the research itself defunded, even the accumulated data put at risk of destruction.
  13. iceaura Valued Senior Member

    For those interested in keeping up with the observations of facts and conclusions to be drawn, this:

    It's long, but there are pictures.

    The single most significant takeaway, imho, is in section 15, page 411:
    Last edited: Nov 4, 2017

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