After how long? A half-life of a decade, as I understand it? Not exactly the order of magnitude of luxury time we have to spare.
> Even if it did increase warming more than CO2
"Even if it did" is strange wording for an established fact. Do you write "even if the sky was blue"?
> once methane emissions reach a steady level, reducing methane emissions won't change a thing
It's kind of really, really important how high that "steady level" is and how fast we'd reach it though, no? We're not just worried about life 1,000 years from now. We're worried about life 20 years from now.
> The narrative is extremely misleading.
I find this statement strange after reading your comment.
(Update: In hindsight I'm not sure you were talking about methane emissions in general or about methane from meat production. Here, I'm focussing on the latter. Meanwhile, fossil methane is of course a huge problem.)
As for the second part of your question: When it comes to meat production, we have already reached the steady state.
As for the first part: Yes. But it is not that high. Let's say the total amount of greenhouse gases in the atmosphere due to cattle (and rice and other types of agriculture) account for a fraction X of the world's yearly emissions. (In Germany, for instance, X = 0.06, i.e. 6%.) Let's assume for simplicity the remaining emissions are exclusively due to fossil fuels and all emissions are the same every year. Let Y be the fraction of agricultural emissions relative to fossil emissions, i.e. Y = X/(1-X). (= 6.4% for Germany)
Then, after N years, the amount of greenhouse gases in the atmosphere due to agriculture, relative to the amount of greenhouse gases in the atmosphere due to fossil fuels (burned during that timeframe) will be Y/N. This is because agricultural greenhouse gases in the atmosphere will stay constant – because we're in a steady state – but greenhouse gases due to fossil fuels will keep on accumulating.
Putting e.g. N=20 yields Y/N = 0.3% (for Germany). N=100 yields 0.06%.
In short, the amount is negligible. Fossil fuels are a real problem when it comes to climate change, agriculture is not.
Well yes but also no, we've reached a steady state. If we reduce meat production we would reach a new, lower steady state which would buy some more time.
That's right but your claim that this
> would buy some more time
completely ignores my (admittedly back-of-the-envelope) calculation. Please do point out if there's an error somewhere but until then I will stand by my point: Emissions from meat production – even with meat consumption as high as it is these days – are negligible in the grand scheme of things. We better focus our efforts elsewhere.
Besides, what kind of food would we replace the meat with? That food would also need to be grown, harvested, transported, and so on. In the end, we might not gain much in terms of greenhouse gases.
Methane from fossil fuels is a problem, however.
Doesn't matter, if we keep the number of heads of cattle constant, the methane from them in the atmosphere will be constant.
If we keep using the same number of ICE cars otoh, the CO2 from them in the atmosphere will keep increasing. We would have to drop the number of ICE cars to 0 to stop the increase.
It's sourcing food from petroleum that causes the problem.
There are two directions to look at it: convincing yourself via a convincing story, or convincing yourself via a convincing calculation.
The story they tell defies basic thermodynamic intuition, and seems to skip over all the parts that would put the narrative in doubt.
The premise is that greenhouse gases absorb black body radiation from the surface.
First of all, greenhouse gas is a bad name, greenhouses warm because of air convection. So the "greenhouse" intuition they try to abuse is misleading.
Secondly, think about this thought experiment: a layer of pure CO2 gas covers the lowest layer of air near the surface. By how much would that get warmer compared to air? The answer is there won't be any difference. That's because the surface and the air near it are at the same temperature, so they emit exactly the same amount of energy. All systems with same temperature are at an equilibrium.
So what can possibly cause warming is only the effect of the difference in temperatures between the CO2 gas and the surface. Which should only be significant in higher altitudes. Which have much less CO2 because it is heavier. And it's also not clear, in this situation, in which direction the weather near the surface will change.
But then you realize there are also effects of increasing methane / CO2 which decrease warming. The most obvious effect is that they have higher heat capacity. Heat capacity goes together with absorption: the absorption is possible only because the molecules have more degrees of freedom to vibrate. So it's usually around the same order of magnitude. And higher heat capacity means faster cooling from convection and it means the air requires more energy to heat up. In fact, you can think of the entire climate change claim as a statement about the entire earth heat capacity.
So I'm entirely unconvinced by the story. But that should've been OK because there are detailed calculations. There are models.
Except these models are dumpster fire. You can download some of them from NASA's website and judge the quality of code for yourself. Old fortran code, all the models copy code from each other, many things which aren't constant physically are constant in the code, functions full of tens of "if else" statements whose physical validity is highly in question.
But those models should've been tested? Except they don't. There's no way to test them. From basic software engineering perspective, it is insane to trust these things to make the kind of trillion dollar decisions they make.
But all models point to climate change! Well they all copy code from each other. But that's not the only problem. They are all thermodynamic simulations which substitute the full state of the system with average states.
In other words, they all, by design, underestimate the entropy of the system. And thermodynamic energy is entropy times temperature, and since they get the energy right (just the sun) you expect them all to get higher temperature. So it is actually expected from all simulations to overestimate warming.
There are also other glaring counter intuitive things about the narrative. Somehow CO2 effects continue to work slowly over decades, and the system doesn't reach an equilibrium with the current levels of CO2 until decades ahead.
This is completely against normal thermodynamic intuition. Meta stable states exist, yes, and there are out of equilibrium systems. But usually the reason for systems not reaching the more stable state, is that their fluctuations are too small. In this case, the fluctuations are much much bigger than the supposed stable state change. We're talking about barely a degree change over decades in systems that fluctuate by several degrees daily. It makes no sense to claim their equilibrium will only be reached in decades while their fluctuation exceeds the difference to equilibrium daily.
This is wrong. If you do the math, you actually find that you get warming from CO2 if the atmosphere is colder, the same temp, or hotter than the surface.
When the ground emits a photon there are two possibilities. it either gets absorbed by an atom in the atmosphere or it goes to space. about half of the photons absorbed by the atmosphere get radiated back to the earth (compared to roughly zero percent of the ones that go to space).
Since CO2 is better than air at absorbing infrared radiation, it traps some energy that would otherwise be lost. The situation isn't really any different than wearing a coat. a jacket will warm you even if the jacket is colder than you are because it prevents some heat from leaving the system. this doesn't violate thermodynamics because the jacket itself isn't causing warming, it's just preventing heat loss to a colder source.
The better comparison is to a black hole. Literally nothing can escape it - not even light - so it is much worse than CO2. Yet it still has a temperature, and it still emits radiation according to its temperature. You cannot absorb more than black body.
The "better than air at absorbing" isn't an arbitrary statement. It comes from extra degrees of freedom in the gas that can absorb the heat. And the difference in absorbing thermal heat between any two systems MUST be a result of their temperature difference, because they must be at equilibrium if they have the same temperature.
If any two systems of the same temperature had a difference in energy emitted by radiation between them, that would violate the second law, and you would create temperature differences between them (heat would flow) and extract work from the temperature difference without needing a colder reservoir.
My understanding is that CO2 being heavier results in it having lower concentration only at very high altitudes, which are irrelevant for CO2-caused warming. At the relevant altitudes, it's well mixed due to winds.
In the basic mechanism as I understand it, what's relevant is the altitude at which a photon emitted by CO2 is likely to escape to space, rather than being reabsorbed by another CO2 molecule. If CO2 concentration is increased, this altitude goes up, to where CO2 concentration is the same as before. At higher altitudes, the temperature is lower, so emission is from a colder gas, which means less energy is emitted. This isn't a stable situation, however, since the amount of energy coming in is the same as before. Equilibrium is restored when the whole atmosphere heats up a bit, so the temperature at the altitude where photons escape to space is the same as before.
Understanding this makes the discussion about positive feedback from water vapour seem more iffy. Warming is supposed to increase H2O in the atmosphere, which is a greenhouse gas, indeed, the one with most effect. But all that matters is the amount of H2O at the altitude where photons are emitted to space. What happens at that altitude seems like a very complex question, so one is really back to trusting the simulations, which as you say don't seem all that trustworthy.
Disclaimer: Not really a physicist.
This shows you have a complete misunderstanding of the basic physics going on.
If you have a source of radiation directly hitting a surface, some of the radiation will warm the surface by being absorbed by the surface material, but some of that radiation will be reflected back into space. When you add air on top of such surface, the air will capture both some of the direct radiation, as well as some of the reflected radiation. That's what causes extra warming of the surface compared to the situation without air. Now, air is a mix of several gases... different gases absorb very different amounts of radiation in the sunlight spectrum... what we're saying when we say methane is much more powerful as a greenhouse gas than CO2, is that methane can absorb much more radiation, which makes it warm up much more than CO2, and that heat stays around until dissipated back into space, which takes quite a long time!
Now that you understand the process at play, I hope it's obvious that your comment above is incredibly wrong on so many levels. IT's ok to be wrong, but I hope you're able to look for what's real and try to understand things better to avoid making such comments that may lead innocent people into a complete misunderstanding of the situation.
While this effect may be real, it's not what people are referring to as the "greenhouse effect". This requires the absorption and re-emission as IR. Methane and CO2 are considered greenhouse gases because they absorb thermal IR, not because they absorb reflected light from the surface.
In addition to the Wikipedia article machina_ex_deus linked, this might be a good intro: http://forecast.uchicago.edu/archer.ch4.greenhouse_gases.pdf. I'm not sure if I buy all of machina_ex_deus's conclusions, but I think his description of the effect is much closer to accurate than yours.
Do you have any background in physics at all? Seems like you don't really understand physics.
Here, wikipedia's entry:
https://en.m.wikipedia.org/wiki/Greenhouse_effect
The warm surface emits thermal radiation in IR, which is what is absorbed by greenhouse gases.
That's not your fault, their explanation is extremely misleading, like I have said.
You've added an assumption in your question that the entire atmosphere is at the same temperature. This is trivially false; the atmosphere varies greatly in temperature. Some levels of the atmosphere can heat others, and indeed would do so more if those levels are composed of gasses which absorb more energy in the frequencies emitted, like CO2 does in practice.
> the absorption is possible only because the molecules have more degrees of freedom to vibrate.
The gases in the atmosphere are not blackbodies. They absorb different amounts of radiation at different frequencies because of those vibrational modes. If you substitute a gas in the atmosphere that absorbs no infrared with one that absorbs a lot of infrared, the atmosphere overall absorbs more energy and therefore warms.
> Except these models are dumpster fire. You can download some of them from NASA's website and judge the quality of code for yourself. Old fortran code, all the models copy code from each other,
The code quality has absolutely nothing to do with the predictive power of those models. Unless you have found bugs in the code, this is irrelevant.
> many things which aren't constant physically are constant in the code, functions full of tens of "if else" statements whose physical validity is highly in question.
Of course simplifying assumptions have been made. Can you point to an example of a variable made constant that you think is an oversimplification that would change the predictions so drastically as to remove warming from added CO2?
> There are also other glaring counter intuitive things about the narrative. Somehow CO2 effects continue to work slowly over decades, and the system doesn't reach an equilibrium with the current levels of CO2 until decades ahead.
I'm really not sure what you're trying to say here. It seems like you're implying that all thermodynamic changes to a system have to occur instantaneously. We may also not reach equilibrium for a very long time, if (as is very possible!) the warming of the Earth decreases its albedo.
> This is completely against normal thermodynamic intuition. Meta stable states exist, yes, and there are out of equilibrium systems. But usually the reason for systems not reaching the more stable state, is that their fluctuations are too small. In this case, the fluctuations are much much bigger than the supposed stable state change. We're talking about barely a degree change over decades in systems that fluctuate by several degrees daily. It makes no sense to claim their equilibrium will only be reached in decades while their fluctuation exceeds the difference to equilibrium daily.
I'm sorry, but your understanding of thermodynamics is extremely flawed. Metastable states have nothing to do with this. You are also making the basic error of confusing weather with climate here. The temperature increase that is discussed in climate science is an increase in the total energy of the atmosphere. By increasing the ability of the atmosphere to absorb energy, you increase its energy.
You are also arguing against models but have completely failed to address the fact that the atmosphere _is warming_. This is being measured and is no longer a hypothetical.
Then the part where I'm not at all certain about which direction the effect should be, is because while CO2 decreases thermal conductivity by radiation, it increases thermal conductivity by convection because the heat capacity is higher for CO2. Which is actually a much better intuition if you want to understand how does water vapor seems to have such negligible effect despite the fact it is a "greenhouse gas" and "absorbs much more heat".
You want me to point out bugs? There are like 20 different climate models. I've seen heat capacity being constant independent of pressure, temperature, CO2, density, etc. Not just heat capacity, but also other "constants". Not in a single place because the code is a mess, they actually have several different modules with different constants, so say the radiation simulation is extremely detailed mess that's completely unreadable, and the cloud simulation just starts all over with their own different constants.
Writing such code is somewhat human task, but reasoning about the magnitude of the mess that is going on there and which directions the errors will go is beyond the capabilities of anyone. It could be possible but not with the way it's currently written.
I'm sorry, but it is your thermodynamic intuition that's completely wrong. Equilibrium to you means "things stop moving". That... not how thermodynamics works at all. The reason that ordinary things look like they are "not moving" in equilibrium in your everyday life is because they do move, but at scales much smaller than you. Do the Brownian motion experiment.
And meta-stable states have everything to do with this, again this is your lack of understanding of physics, not mine. Given a thermodynamic system, there's expansion around the meta stable state or the unstable state over time, where you get the duration to reach equilibrium from the size of the fluctuations. The gist of the expansion is that what delays reaching equilibrium is that the fluctuations are too small.
There's infinite reasons why warming might be happening. Just the direction itself is a single bit of information with no significance whatsoever. It isn't worth my time arguing against a theory whose statistical strength is one bit.
The models don't have any significance beyond this bit or maybe two bits if you try to be generous about their abysmal performance regarding temperatures. They had some success at very high attitudes, but that's not surprising as these high attitudes are just so much simpler to predict and have no bearing on the rest of the model and the actual climate as observed on the ground. They excuse their shortcoming as the "weather", but if your models don't have any feedback from reality and testing around the parts that matter, why should I trust them ?
Strange coincidence, or maybe the fact that the code is fortran doesn’t say anything about the accuracy of the math.
(I didn't do it, it was probably done long time ago by a moderator).
I just feel bad looking at someone who doesn't know he's wasting time writing things nobody will see. Even if he only snarkly disagrees with me.
Also, if you engaged seriously, maybe they wouldn't ban you in the first place. I just don't believe in ignoring people who are wrong, only in correcting them.
