Methane may not warm the Earth quite as much as previously thought

I had hoped by now humanity would be moving deeply into rationality, but we're still just as emotion-driven as ever. We come by it honestly since our neurology is tuned to handle most (or maybe all) decisions subconciously and then have our conscious/rational mind justify the decision after the fact, but I do believe that by understanding our biology and implementing systems/approaches to combat it, we could become a highly logical species. There is still some hope on the horizon. Live long and prosper my friend.

IIRC (but I am way less certain of this) there's also extra issue with methane degrading into not only CO2, but also water, and in a place where they increase the greenhouse effect rather than reducing it ?

P.S.: Also water vapor is an extremely powerful greenhouse gas... but I have no idea which fraction of water ends up in this phase under these conditions, nor how long water lasts there...

P.P.S.: Oh, also, I just remembered : CH4 (+X O2) => CO2 + H2O, is just one of many reactions that happen... IIRC this is also where the ozone layer is and all of these ingredients and products all have an effect. But in the end it's all oversimplified into CO2 has this greenhouse effect, and CH4 that one - by the climatologists ?

(All of this from climatology 101 that I had to take a decade ago, because there was no other option for a remote physics degree...)

If we removed literally all methane from the atmosphere, this would be equivalent to reducing carbon dioxide concentration to 380 ppm. This would bring us back to climate of 2005. By any reasonable measure, climate in 2023 is not significantly different than the climate in 2005 (eg. you’d hardly be able to observe any difference without making a lot of very careful measurements, you wouldn’t “feel” any difference on your own skin).

And that’s if we remove literally all methane. Most of the methane in atmosphere is a result of natural processes, not caused by human activity. Thus, if we stop all methane emissions caused by human activity, we can maybe at best slow down climate change by 10 years. In terms of practical effects as felt by human beings, this is accurately described as “won’t change a thing”. Actually, to be more specific, slowing climate change by 10 years won’t make any difference, but stopping all methane emitting activities would be tremendously negative to human flourishing.

This is because the methane is being converted to CO2 at a relatively quick clip.

The timescale for CO2 is larger-- centuries.

https://cleantechnica.com/2021/02/06/a-differential-equation...

The fertilizer contributes nitrogen and other minerals. Eliminating agricultural emissions should involve non fuel nitrogen fixation, not methane reduction.

By that logic the only climate change relevant source of greenhouse gases are ones that introduce new ones into the circle, which is pretty much only burning fossil fuel.

It's a pretty old argument that holds some truth, (the fossil fuels are the biggest issue) but is also been debunked by people much smarter then me

In terms of climate change it’s not a 10 years thing and then methane instantly swaps, it’s a second by second thing where a percentage of existing methane is constantly converted. In steady state new methane from say cow farts 1:1 replaces methane from past cow farts being transformed into CO2. The only difference is an atom of CH4 at 16.043 grams per mol weigh less than an atom of CO2 at 44.009 grams per mol. Though many sources of CH4 start by extracting atmospheric CO2, natural gas leaks don’t.

The critical difference is if we cut net CO2 and hold methane steady the atmosphere stops warming, where cutting methane and CO2 would actually cool the atmosphere.

Put another way NEW sources of methane are different because it takes multiple years to reach an equilibrium. In the first years they have a very big impact, but eventually it falls off until eventually a constant source of CO2 may actually have a larger impact.

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.

(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.

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.

Methane from fossil fuels is a problem, however.

It's not like mammalian herbivores are a recent invention. If a constant amount of mammalian herbivores in the world would cause a constant acceleration of greenhouse effect then the greenhouse effect would have increased exponentially for millions of years already. That has not been the case.

If you increase the number of mammalian herbivores in the world then the greenhouse effect will increase for about a decade because of increasing levels of methane. After a decade, the methane level (and therefore the greenhouse effect) will have found a new (higher) equilibrium and no longer increase.

Source? I understood that the long-term radiative forcing of methane was lower than CO2, which is incompatible with this claim.

This is not correct. We are already in a steady state. Methane levels due to cattle are already at their maximum (given a fixed amount of cattle).

At any point in time, gras will absorb some CO2 from the atmosphere, cattle will convert some gras / carbon into methane and emit the latter into the atmosphere, and some methane in the atmosphere will decompose into CO2. This is a continuous process, that's happening every second, and if the amount of cattle is kept constant, there is a maximum amount of methane that you can reach in the atmosphere as well as a maximum amount of CO2. After all, the total amount of carbon involved in the process is constant – energy conservation dictates that mass doesn't appear out of nowhere.

In fact, since we've been doing agriculture for a time much longer than the time scale in which grass grows, a cow digests grass or methane decomposes into CO2, this whole closed loop has already settled into a steady state: At any point in time, the amounts of methane and CO2 in the atmosphere due to cattle are constant. The resulting radiative forcing will thus stay constant, too.

http://www.museumgolling.at/wp-content/uploads/2022/09/9_Sch...

These wisent remains from alpine caves are all from sites now in the subalpine to alpine zone. From this it can be concluded that the beech limit but also the forest line during the »wisent time« (6,000 to 1,200 years before today) was much higher and the average summer temperature had to be at least 3 to 6 °C higher than today

Oaks (Quercus) at an altitude of 1,450 metres around 2,000 years ago also indicate a climate approximately 4 to 7 °C warmer than today

There's a lot of evidence pointing in the same direction.

https://www.nature.com/articles/s41598-020-67281-2

This record comparison consistently shows the Roman as the warmest period of the last 2 kyr, about 2 °C warmer than average values for the late centuries for the Sicily and Western Mediterranean regions.

Yet according to scientists, "Temperature rises over 2 degrees could bring catastrophic and potentially irreversible impacts, including pushing three billion people into chronic water scarcity."

https://edition.cnn.com/2023/01/30/world/global-warming-crit...

It is not comparable to the current system with domesticated animals at all.

It is not.

Domesticated cows make up approximately 35% of the world's mammal biomass. That's the same as humans. All wild land animals combined - all the ones you mentioned and many more - make up around 2%.

One source: https://ourworldindata.org/wild-mammals-birds-biomass

The domesticated chicken is, for example, by far the most common bird with a population about 15 times larger than the second.

Humans make up between 30-40% of land mammal biomass, wild animals around 4% and domesticated animals make up the rest.

We have altered the ecological balance to an insane extent. Animal husbandry use almost 80% of arable land.

The wild animals are also a part of a circular ecosystem. They are, in contrast to domesticated animals, carbon neutral in most cases.

I am writing this on a slow GPRS connection, so I can't provide you with sources, but they are readily available. Both papers and news coverage. I managed to get into this page, but that is all: https://ourworldindata.org/wild-mammals-birds-biomass

The question I am investigating is an input to such calculations; I am not qualified to estimate the impact.

Yes, the average temperature of earth has chaged vastly over its history, giving different levels of habitability.

At this time, we're in a really good spot for habitability, and we are seeing that we are slipping out of it.

There is evidence that some of the temperature change could very well be human made, and thus easy to stop (compared to, say, the emissions of volcanoes).

For some reason you argue that nothing should be done, because nothing was done in past massive climate changes, which resolved in mass extinctions.

Is anything I'm saying wrong?

13 misconceptions about global warming

an 8 year old video

And that argument works better in reverse anyway: we're talking about a trend implying large parts of the planet becoming uninhabitable for present levels of human population within a relatively short time frame (which will also have an effect on economic activity!). If contrarians really have a good faith belief that this trend is caused by some other factor and will be self correcting, perhaps they could deign to specify their own testable assumptions and make their own model...

Or perhaps a "scientist" has spotted a suspected cancer in your brain but they can't quite pinpoint whether it's a 20x increase from normal size or a 28x increase. Based on the 28 assumption, you'll be in a wheelchair within seven years, but it might also be ten years. It's entirely preventable by doing the surgery but that costs money today plus minor lifestyle changes. Before doing a costly operation and bothering with, say, a daily pill and no alcohol, one could choose to wait while they refine their equipment over the next decades and then measure again before taking serious action. Can't trust dem scientists anyway, maybe it wasn't a problem in the first place.

That's the logic I'm seeing here. A "times worse than CO2" value for one of the elements might have been off by 30% so we should just assume nothing is wrong in the first place and not change our society away from burning carbon. Maybe it's just a coincidence that ~five of the past ten summers are the hottest of all the summers whose temperature we've measured... yeah I agree: maybe. It's a possibility, no matter how remote. But I'd rather not wager with billions of lives impacted by the outcomes that are part obvious (sea level rise) and part the prediction from yet more models. We needed to act yesterday if the models are anywhere near the truth and it's going to get exponentially harder to fix the longer we wait (because reducing emissions year-on-year is a lot easier than cutting+capturing at a moment's notice). If it turns out to be a dud, we can continue to dig up the remaining oil and have a big feast, everyone happy. If not, it's a good thing we acted and we're probably still not going to be able to prevent some level of habitat damage for the species we call human, but at least it won't be as bad as when we wait for more precise information on a problem where the conclusion remains unchanged.

(That's besides the healthy years of life provided by having cleaner air; I don't know how that would compare against e.g. cobalt mining.)

I'm not sure what sort of model you used to arrive at this vague estimate, but:

Even if you assume AGW science is completely wrong and the effect is zero, humans have to move from fossil fuels to renewables/nuclear in that timeframe anyway, because we have 47 years of oil left. Whether it's 20 years or 80 years, still needs to happen.

As a climate scientist myself, I can tell you this is untrue and a harmful legend. As climate science is mostly atmospheric physics, biology and chemistry, it's pretty much very easy to disagree with anyone if you have a good argument supported by data. If you have strong scientific arguments, it does not matter even if the whole world is against you. On the contrary, this will likely make you famous and secure your career. Scientists (at least the curios ones) love to be proven wrong.

EDIT: spelling

People who have never done science really like this idea of the general scientific community being some sort of secret society that agrees to support eachothers ideas.

If you put 5 scientists in a room, you can't get them to agree on >anything<. The idea that disagreement is enough to get you outcast from "science" is complete nonsense.

Did you actually look at what you linked?

The main graph is only China and India and already shows a net inflection for China in the past few years. It will keep slowing. Read about population-lag effect.

The second graph nicely confirms that contrary to what you pretend population growth has started slowing globally.

There is no consensus about how much it will slow and when the peak will be reached. IPCCC had to adjust their hypotheses in the past because the lowest credible estimation where falling outside the lowest considered by the first climate model and some specialist argue we should look at even lower prediction. People in developing nations have stopped having large families faster than we thought.

> So it's not clear why you bring up population growth. It's not relevant.

If you don’t see how population size affects consumption, production and in fine pollution, I can’t do much for you.

> What is it and how is this impact measured in an undeniable way. It can't be temperatures because they don't track CO2 levels.

You are clearly arguing in bad faith or are clueless about the research surrounding climate change. In both case, I think it would be a waste of my time arguing further.

A 30% reduction serves to further show that the priority needs to be CO2 in general, and everything but the low hanging fruit for methane emissions is a distraction.

Of course, the possibility of runaway effects and short term positive feedback loops from methane release from permafrost, etc, is still a concern. I guess a 30% reduction there is somewhat good news.

Right, which is why arguments about going vegan advocate for having fewer cows, which kind of renders the rest of your argument moot.