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Menopausal Mother Nature

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365 Days of Climate Awareness 319 – Global Warming Potential – Daily Kos


319CO2.png
Atmospheric carbon dioxide concentration.

Global warming potential is treated as a scalar: that is to say, a number without units, because all greenhouse gases are compared to carbon dioxide. CO2, by definition, has a GWP of 1. Since the gases have vastly different lifetimes: carbon dioxide, roughly 120 years, methane roughly 10.4, and CFCs less than that, their warming potential is averaged into a 100-year span. A few principle gases, using this 100-year average, are listed below. (For concentrations: ppm = parts per million; ppb = parts per billion; ppt = parts per trillion.)

  1. 319CH4.png
    Atmospheric methane concentration.

         Carbon dioxide (CO2): GWP = 1; lifetime ~120 yrs (but can vary widely); 410 ppm

  2.      Methane (CH4): GWP = 28; lifetime = 10.5 yrs; 1,800 ppb
  3.      Nitrous oxide (N2O): GWP = 265; lifetime = 132 yrs; 380 ppb
  4.      Various chlorofluorocarbons (CFCs): 4,660-13,900; lifetimes 16-500 yrs; 1-100 ppt
  5.      Sulfur hexafluoride (SF6): GWP = 23,500; lifetime = 3,200 yrs; 10 ppt
319N2O.png
Atmospheric nitrous oxide concentration.

Different time frames (20 years, 200 years) are used by different agencies around the world, but the concept is the same: amount of energy absorbed by a given mass of greenhouse gas during that timEPA – greenhouse gas concentrationse, given the average solar input of roughly 1.366 kW/sq m. With this statistical tool scientists can directly compare the impacts of various gases, though for high-resolution climate modeling, the different gases with their distinct behaviors are accounted for separately.

Tomorrow: introduction to general circulation models.

319CFCs.png
Atmospheric concentrations of various fluorocarbons and other chemicals.

Be brave, be steadfast, and be well.

Sources

EPA  — Understanding Global Warming Potentials

GHGprotocol.org

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