ClimateProgress: We are 80 ppm of CO2 away from extinction

Does Joe Romm know that the next 80 ppm of atmospheric CO2 will have less effect on the atmosphere than the previous 80 ppm?

Read “Doubling Of CO2 Levels In End-Triassic Extinction Killed Off Three Quarters Of Land And Sea Species.”

Well, how much does carbon dioxide heat the Earth?

Oh my, we were afraid you were going to ask that. Because so many of the atmospheric processes are still being sorted out and quantified this is a non-trivial task. But alright, here goes.

What we can do is plot some of the more common estimates — note that these are something of a curve-fitting exercise on our part because we don’t have the full papers and workings at hand. Stay with us while we run through a couple of rough sketch graphs, following which we’ll try a different approach to see if we can’t narrow the possibilities.

We’ll offer three of the more commonly used and/or discussed estimates for the amount of cooling Earth would experience for a hypothetical zero-CO2, cloud-free atmosphere

  • Lindzen (5.3 °C clear sky, 3.53 °C with 40% cloud);
  • Charnock & Shine (12 °C clear sky), C&S are the big number guys in the estimation game (both these from Physics Today, 1995); and
  • Kondratjew & Moskalenko (7.2 °C, commonly cited but we are not sure why, perhaps because Houghton used their estimate in his book, ‘The Global Climate’, 1984).

co2greenhouse-X2 032413

Here these estimates are simply scripted up to produce the following graphs and the numbers are imprecise, merely adequate to give everyone a reasonable look at how carbon dioxide fits into the picture.

Note also that there is still dispute over whether water would (does) act as a positive or negative “feedback” (multiplier effect) since water vapor and droplets (clouds) affect both incoming Solar radiation and outgoing Earth radiation.

Our simple script is logarithmic (remember our example of adding more shades over a window) but does not allow for complete saturation of radiative wavelengths, likely increases in evapo-transpirative cooling, increases in albedo (bright clouds reflecting more incoming solar radiation) nor any variation by latitude and so will progressively overestimate potential warming from CO2 alone. No matter, it does quite well enough to demonstrate the principle.

co2greenhouse-X4 032413

You can see how much this little script has overshot the mark since Lindzen states explicitly that a doubling from 300ppmv to 600ppmv of atmospheric carbon dioxide would result in only 0.5 °C warming. Rather obviously, Lindzen’s calculations do not suggest a particularly large greenhouse influence on post-Industrial Revolution temperatures and, significantly, this does not include clouds, so CO2 would really only be a fraction of the total effect shown (Lindzen states 0.22 °C if calculated with 40% cloud cover).

Despite our over-estimation of the numbers on the graph it should be apparent there is only moderate warming potential from carbon dioxide emissions. These have all been plotted simultaneously so you can see the range of estimates for incremental change in temperature driven by greenhouse gases and below we show for a quadrupling of CO2-equivalent greenhouse gas relative to pre-Industrial Revolution levels.

Since some people are not familiar with logarithmic effect, we’ll just point out a few features from the above graphs. Note the diminishing effect in all cases — the first half of pre-IR greenhouse-driven temperature increment in each estimate is achieved by less than 20 parts per million carbon dioxide (20ppmv CO2), it then took adding thirteen times as much again to repeat the performance (to 280ppmv). The estimated temperature increment range for a doubling of pre-IR CO2 (graphed as 300ppmv to 600ppmv) is just +0.6 °C to +1.5 °C and for a quadrupling (to 1200ppmv) +1.3 °C to +2.9 °C.

5 thoughts on “ClimateProgress: We are 80 ppm of CO2 away from extinction”

  1. I apologize for being blunt, but Shut your trap.

    We have gone over this time and time again. Of course the presense of a cold body can warm a warm body. Radiative effects do not consider the temperature of the receiving object because they are two independent events. The cold body emitts radiation blackbody radiation due to its temperature. This radiation strikes the warm body, warming it. The greenhouse gas effect is real, it’s existence is proven, and attempting to deny that basic fact is the WORST thing you can do while debating in a skeptical forum. The argument is over its magnitude in direct warming and in amplified warming.

    Don’t try and debunk science when you have only a sophomoric knowledge of the underlying physics.

  2. I t’s all fine and dandy to do lots of calculation regarding CO2’s ability to cause warming, BUT, and a big but, it is meaningless.

    The entire CO2 warming climate meme depends on the upper troposphere warming the surface and doing so because of added CO2.

    As long as the upper troposphere is at -17 deg C and the surface at 15 deg C, it is impossible for warming to occur. A cold body cannot warm a hot body—those lower energy levels, corresponding to the colder body’s radiation, are already full in the hot body and will be reflected back upwards to be lost to space. This is basic thermodynamics and not a stretch. However, such basic science is totally ignored in order to pretend that CO2 has the claimed effect.

    The required hotspot for the warmists’ model is missing entirely in the real world—the upper troposphere has actually been cooling a bit. But, they ignore these inconvenient facts and blather on about the (nonexistent) greenhouse effect, a piece of never validated conjecture by Arrhenius in the 1800s.

    CO2 or any other gas at any concentration in the atmosphere cannot warm the climate. The basic starting temperature of the atmosphere is due to gravitational compression and moderated from there by solar input and ocean cycles.

  3. This is hilarious on the part of the Climate Astrologers, in that they attempt to create something out of nowhere. Most scientists think that the extinction event was caused by a combination of the breakup of Pangaea along with the massive accompanying volcanic activity. Some scientists say this would have actually caused global cooling.

    And, really, what would have caused the jump in CO2 back then? Fossil fueled cars driven by condodonts and proto-reptiles?

  4. “We are 80 ppm of CO2 away from extinction”.

    Yes, I hope you are right in fact I think your extinction should be brought forward to 10 ppm.

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