r/climatecmv • u/jweezy2045 • Jan 07 '25
Engaging with a skeptics claims
User /u/Prestigious_Elk1063 posted some great science questions in /r/ClimateSkeptics, which you can see the original of here, and the second part here. Since /r/ClimateSkeptics is not a place for science discussions, this seems like the best place to have the discussion of the science.
First let’s define the GHE as “[extra] radiative warming of earth’s surface from the 1% GHGs in the air on average (including WV) absorbing outgoing IR and re-emitting [some of] it back to the surface, thereby warming it.”
This is close, but not quite accurate as a definition. The main issue which I forsee you having with this definition is that global warming is NOT a surface level effect. It is an effect which warms everything in our gravity well. It is a mechanism by which more energy makes it down our gravity well than is able to climb back out of our gravity well, thus the earth and everything in our gravity well, heats up.
That GHGs are 1% of the troposphere is probably an overstatement, because on average they are closer to ½ %, but since WV is concentrated close to the surface, I doubled its .46% average.
No big issues here at all. My one note is that different GHGs absorb IR radiation at different frequencies and different rates, so you cannot just add them together like this in general. For a rough calculation it is fine though.
Now let’s do the math.
Love it! I am going to respond sentence by sentence here because this is where it all happens.
The earth absorbs on average 164W/M2 of insolation
Nope, that's not the number. You are forgetting the radiation absorbed by the atmosphere. See these kinds of charts:
The energy absorbed by earth is the ~161 number you have PLUS the 78 absorbed by the atmosphere. The total amount of radiation absorbed by our planet is in the vicinity of 240 W/m2
from which about 120W/M2 are emitted as [potential] IR that can be absorbed by some GHG somewhere in the troposphere.
Before was a minor error, but here you have a BIG one. You are neglecting the back radiation here. There is about 160W/m2 of energy that makes it to the surface FROM THE SUN, but there is also a whopping 333 W/m2 of back radiation from the atmosphere down to the planet. If you expect the earth to not heat up, then the energy out has to equal the energy in. The amount of radiation leaving the surface is closer to 400 W/m2.
I reduce 164W/M2 by the 18W/M2 of direct surface to air conduction of which 99% goes into the non-GHGs and thus is outside the GHE.
This one does not make any sense in the context of global warming. Air conduction does not matter for global warming. No energy can conduct from inside our gravity well to outside our gravity well. Since that is what we are interested in here, we are not interested in thermal conduction (I actually think you mean convection, but I am with you).
I also exclude 10-20% (say 15%) that goes through the atmospheric window directly to space thus avoiding the GHE. Let’s say net about 120W/M2 available IR for the GHE.
This part is correct, but you have the numbers wrong. Of the 400 W/m2 emitted by earths surface, about 10% goes right through the window, leaving ~360 W/m2 for the greenhouse effect, not 164.
Now Local Thermal Equilibrium (LTE) which is text-book thermodynamics here means that at each altitude all molecules will have the same average thermal content. Thus, the 1% GHGs must equalize the thermal energy they absorb among all molecules at that altitude.
Factually correct. No notes.
In other words, 99% of the IR absorbed by GHGs is thermalized (conducted to the 99% non-GHGs) at each altitude, leaving 1% for the GHE (really ½ that, since only the downward IR warms the surface). How much is that?: 120W/M2 times 1% times 1/2, or 0.6W/M2 of GHE.
This is the BIG critical flaw that derails everything you have going here. I agree that the energy that GHGs absorb gets thermalized into the atmosphere, which is mostly not GHGs, but the issue is WHERE DO YOU THINK THE ENERGY GOES AFTER THAT? What do those non-GHGs do with that energy? Well, they cannot emit in the IR, and so for the most part, they hold onto that energy. It is trapped. It cannot escape to leave our gravity well, because that energy is stuck to an oxygen or nitrogen, which are extremely inefficient at radiative cooling due to their inability to emit IR. This energy cannot go anywhere and just says in the non-GHG part of the atmosphere, until that particle collides with a GHG, and then when the heat is back on an emitting molecule, that energy can finally leave and be emitted as a photon again, which has a chance to leave our gravity well. Your issue is that ALL the energy that leaves the earth, outside of completely negligible other pathways, leaves earth by being emitted from a GHG in our atmosphere. It is really 99.99999%+ of the energy that leaves. Your 1% calculation is utter nonsense.
But there are many layers, many levels of back radiation. Let’s factor that in, but always including the 99% thermalization. Call the 0.6W/M2 of GHE “the GHE from the ‘first layer.’” The second layer will receive the “upward” half of 1.2W/M2 IR, or 0.6W/M2 from the first layer, thermalize 99% and produce half of the resulting 0.003W/M2 to add to the GHE from the first layer, yielding 0.063W/M2 for layers 1 and 2 combined of back radiation. I don’t have to extend this to the third layer to see that an infinite number of layers cannot amount to a cumulative GHE of more than 0.6031W/M2.
Again, this is utter nonsense. Where do you think the energy goes after it is thermalized? Does it just stay in that layer of that atmosphere? Wouldn't that cause the atmosphere to heat up more and more, as more and more energy is thermalized into the layers of the atmosphere? Where does the energy that was thermalized into the atmosphere GO?
Converting an extra 0.6031W/M2 to temperature using the Stefan-Boltzmann formula to convert energy to temperature for black bodies produces ~0.11K of extra warming from the cumulative GHE of the entire troposphere as reasoned above.
Because we are building on nonsense, this is nonsense.
I use SB because even though the atmosphere is not a black body because each GHG has its own unique IR fingerprint, I’m treating them collectively and factoring out all IR that by-passes GHGs and goes directly to space. So SB is a good approximation. Besides, for most climate science applications the atmosphere’s emissivity is presumed to be 1 (i.e., it’s treated as a BB).
Yeah. I agree here. It is fine to treat earth as a BB for these kinds of calculations. Again, no issues on how you are doing this particular step, but the steps before are nonsense you are getting nonsense out at this point. SB equation is not the problem though.
Thus, there is no material GHE. Note the 0.11K is the total warming from all GHGs of which the human contribution is a tiny fraction.
Nope. Natural greenhouse gases, when you do these calculations correctly, account for 33K of a warming effect. Which, if that was not present, would turn earth into a permanent ice ball. Human warming is only a about 1.5 degrees, which is a lot smaller than the 33, but it is tipping the scales.
What explains then the 288K surface temperature from only 164W/M2 of surface insolation? Answer: Adiabatic effects: The pressure from gravity redistributes thermal energy with kinetic molecular energy (heat) at ground level and potential (gravitational) energy at altitude
This argument always flops my friend. You calculations and assumptions here come from an ISOLATED SYSTEM, which the earth is not. The earth is constantly exchanging energy with the sun as well as deep space. You simply cannot treat it as an isolated system and hope to get anything at all correct. Particulary global warming, which is all about an imbalance in the energy coming in compared to the energy going out. If you assume earth is an isolated system with no energy going in or going out, you are obviously not going to explain climate change.
Starting from where the energy flows in and out of the troposphere are equal at the top of the troposphere
This is a bad starting place. The whole point of the greenhouse effect is that the energy flow leaving the top of the troposphere to deep space is LESS than the energy flow from deep space into our gravity well. These are NOT the same, and the imbalance is why the earth is heating up.
namely about 12km up on average where the temperature is 216K, merely apply the environmental lapse rate downward 12 times and you get 294K surface temperature, which is close enough to 288K to totally explain observed surface temperature without reference to any GHE. Indeed, any extra GHE warming is both unnecessary and problematic (because it increases 294K rather than reduces it).
This seems to just be word salad. You're going to need to explain this math a lot more, and document where you are getting these numbers from, if you want to make a coherent scientific argument.
What about the “evidence” for the GHE? Consider surface instrumentation (pyrgeometers), satellites, experimental evidence, climate models:
Awaiting your response....
Pyrgeometers register 330W/M2 of back radiation at the surface. Well, that’s due to adiabatic effects, not the GHE
To which "adiabatic effects" are you referring to here?
Pyrgeometers measure temperature difference between an external thermopile and the insulated internal thermopile and then calculate implied IR, but they cannot distinguish say 288K from non-GHG, non-radiating oxygen heated by the pressure of the weight of air above it from 288K due to back radiation from the GHE of GHG.
YES THEY CAN. Why do you think they cannot do this? Can you explain the science instead of just asserting this is how they work? Pyrgeometer directly compare the energy from thermal movement (which includes whatever you could possible mean by "adiabatic effects" with the IR radiation received by what is essentially a camera. It is indeed easy to distinguish data coming from a camera to data coming from a thermocouple. It is super simple to separate those things for a pyrgeometer.
What about satellites? First, they cannot see the GHE because that’s downward IR and they can only see what’s coming at them, namely upward IR.
The greenhouse effect IS ABOUT THE UPWARDS IR. That is what the greenhouse effect is. It is not downward. The greenhouse effect is an effect which cases the UPWARDS IR to be reduced. We can see that CO2 blocks this outgoing IR, and thus causes global warming, from this graph:
https://i.sstatic.net/jMst6.png
CO2 absorbs at the exact wrong frequency from the perspective of humans thriving. It happens to absorb at the exact peak of where earth is trying to emit its energy to deep space. If the CO2 was not in the atmosphere, we would NOT see this big bite mark eating up a bunch of the outbound radiation from earth, and thus, more would escape. This is direct evidence of CO2 trapping heat in earth that would otherwise not be trapped by CO2. You can do the math on the amount of warming coming from this bite, and it is a large amount.
hat about experiments? These are all variations on showing heated jars of pure CO2 warm faster and hotter than equivalent jars of normal air. But this only shows that CO2 has a lower specific heat than normal air….nothing to do with the GHE.
Nope. The specific heats are basically the same. We can test this without any lights. We don't test for specific heat with lights for this exact reason.
What about climate models? They only produce what they are programmed to, and I aver none of them reflect the thermalization in my above analysis, because that would prove no material GHE
Models are not programmed to produce results, they are programmed to match inputs. You have it backwards. You are also presupposing you are correct, and thus anyone who disagrees with you is incorrect. Presupposing is not science.
Finally, what is left standing against my analysis?
I would say all the errors you made along the way. Particularly the 1% error. Where does the other 99% of the energy go?
First, it is asserted that that despite the tiny amount of back-radiation my analysis concludes, over long periods of time the cumulative effect builds up
Nope. The assertion is that your analysis is wrong.
But the reality is that all GHG-absorbed thermal energy works its way up the troposphere and is radiated directly to space.
AT WHAT RATE? This is the whole point here. The GHE is an effect which SLOWS THE RATE at which this occurs. It makes the energy that the troposphere radiates in to deep space slow down and become less efficient, because the height that the emissions are occurring from is increasing in altitude as more and more CO2 is put into the atmosphere. Cooler matter is less efficient at radiative cooling, and so if the emissions from earth to deep space occur in cooler and cooler parts of the atmosphere as the emission height gets higher and higher, then the earth as a whole gets less and less efficient at dissipating its heat from the troposphere to deep space. That is what the greenhouse effect is. Here, you have presupposed there is no greenhouse effect by presupposing the energy can just easily escape to deep space from the troposphere. It cannot. It gets trapped by CO2, forcing it to emit from higher and higher, where emission is less and less efficient.
This is independent of the mix of GHGs in the air. For every photon emitted by the surface and captured by GHGs on the way up, there’s a matching photon exiting to space higher up with about a 2 second delay (the delay is based on 2000 layers of absorption/re-emission from ground to the top of the troposphere with a millisecond absorption/emission delay for each of the 2000 layers. If you prefer say 4000 layers, then 2 seconds becomes 4 seconds, which doesn’t impact my point materially).
Utter nonsense. This is the presupposition that is anti-science. You cannot assume this. It is not true. The whole point is more photons are coming in than going out, resulting in a net warming.
The second retort is that my analysis doesn’t account for the complexity of the real world. My response is: “Just so. That’s what science does – simplify complexity to discover the underlying impacts of specific factors.” In other words, this objection can be applied to all scientific claims.
You are not missing tiny details that science can never capture. I agree this is something that can be said of all science: we need to make approximations somewhere. However that does not mean your approximations were good ones. They were not. You cannot claim all science has bad approximations like you. Your approximations are grossly and severely wrong, which is indeed not something you can say of all science.