What if the Worst Case Models are Right?

[Vice-Regent]

 

[Bhs1975]

 

Then we’re screwed.


.

[BillT]

OR co2 is already impacting as much of the IR spectrum as it can no matter how much more is in the air? IF a dam is holding all the water in the stream does building the dam thicker change anything?

[forkyfork]

Location:walker county alabama

[bdgwx]

4 hours ago, BillT said:

OR co2 is already impacting as much of the IR spectrum as it can no matter how much more is in the air? IF a dam is holding all the water in the stream does building the dam thicker change anything?

This actually isn't true. This myth has it's origins in an experiment Angstrom and his assistant Koch performed shortly after Arrhenius quantified the greenhouse effect of CO2 and actually predicted it would occur as a direct result of human behavior in the distant future. While the Angstrom/Koch experiment was technically correct in proving that the CO2 effect does saturate the interpretation of how this plays out in the atmosphere got badly bungled for multiple reasons, but mostly because scientists at the time treated the atmosphere as if it were a single homogeneous layer...which it isn't. There are a lot of very physics'y related details involved here but the main takaways are this: 1) Even if a layer of the atmosphere is subject to the saturated CO2 effect itself it will STILL warm via other radiation, conduction, and convection processes through the addition of CO2 because not all layers are subject to the saturation effect and 2) It's not even true that the CO2 effect is saturated to begin with.

[Vice-Regent]

14 hours ago, BillT said:

OR co2 is already impacting as much of the IR spectrum as it can no matter how much more is in the air? IF a dam is holding all the water in the stream does building the dam thicker change anything?

That does nothing to explain why the paleoclimate has been warmer than the holocene at times. It's clearly related to the amount of Co2/Water Vapor in the air. They feed on each other in a positive feedback.

[BillT]

11 hours ago, bdgwx said:

This actually isn't true. This myth has it's origins in an experiment Angstrom and his assistant Koch performed shortly after Arrhenius quantified the greenhouse effect of CO2 and actually predicted it would occur as a direct result of human behavior in the distant future. While the Angstrom/Koch experiment was technically correct in proving that the CO2 effect does saturate the interpretation of how this plays out in the atmosphere got badly bungled for multiple reasons, but mostly because scientists at the time treated the atmosphere as if it were a single homogeneous layer...which it isn't. There are a lot of very physics'y related details involved here but the main takaways are this: 1) Even if a layer of the atmosphere is subject to the saturated CO2 effect itself it will STILL warm via other radiation, conduction, and convection processes through the addition of CO2 because not all layers are subject to the saturation effect and 2) It's not even true that the CO2 effect is saturated to begin with.

amazing you admit there is a point of saturation,but dont seem to grasp what that means, doubling co2 will NOT have  HUGE IMPACT in the real world the only place it does is in computer models which pre assign a power to co2 that is doe NOT have.....you even say after saturation other factors will still cause warming and still blame co2 for the other factors because of some computer generated positive feedback.......if some such positive feedback happens solely because of co2 the earth would have been a cinder long before humans were here.......the next poster goes on with thefeedback stuff after the admission it was warmer long ago before humans.......climate change is natural and the climate is nothing but a set of statistics, the climate is not a force has no power and causes NO weather events.

[skierinvermont]

1 hour ago, BillT said:

amazing you admit there is a point of saturation,but dont seem to grasp what that means, doubling co2 will NOT have  HUGE IMPACT in the real world the only place it does is in computer models which pre assign a power to co2 that is doe NOT have.....you even say after saturation other factors will still cause warming and still blame co2 for the other factors because of some computer generated positive feedback.......if some such positive feedback happens solely because of co2 the earth would have been a cinder long before humans were here.......the next poster goes on with thefeedback stuff after the admission it was warmer long ago before humans.......climate change is natural and the climate is nothing but a set of statistics, the climate is not a force has no power and causes NO weather events.

How about we leave physics to physicists? 

As was already pointed out, the absorption spectrum of CO2 is not all or nothing. There are portions of the absorption spectrum that are only partially saturated. This can be seen in the image below.

Second, if you go high enough in the atmosphere concentrations of CO2 are low enough that not all of the IR light is absorbed, thus allowing some light to be emitted to space. As concentrations increase at these higher altitudes, IR light less easily escapes to space.

These two facts have been studied, tested and modeled endlessly by physicists. If you think you have unearthed some secret flaw in physicists understanding of the CO2 effect, you're just uninformed.

 

 

[BillT]

how would a molecule of co2 stop the IR wave leaving the atmosphere please???   are you saying co2 in the upper atmosphere can send IR waves back to the earth?    that co2 has the POWER to reverse the natural movement of the IR wave towards space?????

why did you create a strawman? nobody claimed it is all or nothing....and your appeal to authority is cute but adds NOTHING and is not discussing anything.......what happens if the physicists are LYING? 

[forkyfork]

there's no point in "debating" crackpots 

[bdgwx]

2 hours ago, BillT said:

how would a molecule of co2 stop the IR wave leaving the atmosphere please??? 

It captures the photon in a process called molecular vibration. For example, CO2's bending mode is activated at wavenumber 667. However, due to the nuances of quantum mechanics, doppler shifting, etc. the bending mode isn't always activated at precisely 667. There is partial absorption on the fringe frequencies. So while adding CO2 may not increase absorption at precisely 667 it will increase the probability of photon capture at the fringe frequencies. See skierinvermont's post above. Anyway, this is how polyatomic convert quantized energy into thermal energy. Google for molecular vibration for more information.

2 hours ago, BillT said:

are you saying co2 in the upper atmosphere can send IR waves back to the earth?

Yes! Molecular vibration works in reverse. The molecule can relax back into a lower energy state and emit a photon in the process to carry away the energy. This photon is emitted in a random direction. Half of the emitted photons have downward vectors while half have upward vectors. This is how the radiation gets "trapped". This is the greenhouse gas effect.

This is probably a good time to mention the smoking gun signal for GHG warming. As IR radiation is trapped with increasing magnitude it should work to warm the lower geosphere at the expense of cooling the upper geosphere. Bingo...that's exactly what we observe. That is the troposphere and hydrosphere are warming while the stratosphere cools. No other physical process can explain this unique observation.

 

 

[BillT]

ty for the tone of your response bdgwx.......the release is random with NO directional push at all isnt it? and since the photon was moving away from the earth why when released from the co2 doesnt it continue moving away from the earth?

[bdgwx]

6 hours ago, BillT said:

ty for the tone of your response bdgwx.......the release is random with NO directional push at all isnt it? and since the photon was moving away from the earth why when released from the co2 doesnt it continue moving away from the earth?

Once a photon is "captured" by a polyatomic molecule via molecular vibration it ceases to exist. The quantized energy of the photon is added to the molecule by increasing the kinetic energy of the chemical bonds by causing the individual atoms to vibrate. One way the molecule can "use" this added energy is by creating a new photon with the same frequency as the original (sort of). This new photon is emitted in a random direction. So whereas the original photon may have had an escape vector any resultant photon would only have a 50%'ish probability of having an escape vector. The short answer to your question is that the photon doesn't continue moving away from Earth because it no longer exists.

CO2 is IR active at two primary wavenumbers. They are 667 and 2349. 667 is the most interesting because it lies right in the heart of the highest outgoing radiation flux channels Refer to skierinvermont's plot above. And notice that the molecule is absorbing radiation at both higher and lower frequencies. This happens for several reasons, but I believe the two primary reasons are due to pressure broadening and doppler shifting. Pressure broadening happens when two or more molecules "share" energy. This allows the molecules to work together to capture a photon. The higher the pressure the closer the molecules are and the more likely they are to successfully capture a photon that isn't exactly 667. Doppler shifting refers to the way a molecule will perceive the photon frequency. If the molecule is moving toward/away from the photon then the photon will be blue/red shifted from the molecule's perspective.  Again notice in skierinvermont's graph that the breadth of the absorption spectrum is larger at 300K than it is at 220K. This is due in part to both doppler shifting and pressure broadening because higher temperatures are associated with both higher pressures and higher molecule velocities.

It only takes a few ppm of CO2 to completely saturate the ~14 µm channel (wavenumber 667). Additional concentrations beyond the first few ppm then work to broaden the absorption spectra. The higher the temperature the more the absorption spectra will broaden if given repeated pulses of CO2. This in itself is a type of internal feedback. The more CO2 warms the atmosphere the more the absorption spectra will respond to increasing CO2. But that feedback, like most, is self limiting. All other things being equal this broadening of the absorption spectra will equilibriate. For the lower troposphere this requires a lot of CO2...far more than is currently in the atmosphere.

The takeaway here...depending on your precise meaning of "the CO2 effect is saturate" the answer can either be yes or no. Yes, in that the ~14 µm channel is definitely saturated already, but no, that doesn't mean the entirety of the CO2 effect is saturated because there is plenty of longwave radiation surrounding ~14 µm that is still up for grabs. All of the above (plus other reasons) is why the CO2 effect is proportional to the logarithm of the concentration. Specifically, the radiative forcing is about 5.35 * ln(Cn/Cb) where Cn is the new concentration is Cb is the baseline you want to compare it to. For example, a doubling of CO2 from 280 ppm to 560 ppm would yield 5.35 * ln(560/280) = +3.7 W/m2 of additional force on the climate system.

By the way, side note, the ABI instrument on the new GOES-R satellites is very sensitive to CO2. In fact channel 16 (widely available online) is called the "CO2 channel" because it lies near 14 µm (13.3 µm to be precise). The irony here is that if CO2 or H2O weren't really GHGs then a significant portion of the GOES-16 and GOES-17 satellites would be useless!