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

    Messages:
    178
    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
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. spidergoat Valued Senior Member

    Messages:
    51,605
    Even a "changing" business model is still business as usual. It's all predicated on relatively cheap energy.
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. exchemist Valued Senior Member

    Messages:
    6,134
    Yes, I admit I had my tongue in my cheek when I wrote that.....

    Please Register or Log in to view the hidden image!

     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. iceaura Valued Senior Member

    Messages:
    23,859
    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

    Messages:
    12,676
    Good quote. And fortunately for science, the predictions made by IPCC models are coming true.
     
  9. exchemist Valued Senior Member

    Messages:
    6,134
    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

    Messages:
    2,217
    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

    Messages:
    9,056
    Woody1

    I'm with you.

    People just understand what the mainstream media gives them .
     

Share This Page