Methane may not warm the Earth quite as much as previously thought • Hacker News Board

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

#351

Post by hinkley » Sun, Apr 23, 2023, 4:59 PM UTC

himinlomax wrote: post #260

hinkley wrote: post #13

We just had a conversation the other day about climate change and methane, and some people were saying 20x as strong as CO2, and others were saying and sometimes correcting them to 28. According to this article the correct answer is 20. That’s still over an order of magnitude difference. It still doesn’t change the priorities much, it means you can leak 40% more methane from a system before it’s worse that coal, but…

Methane from organic sources is at a steady state since it oxidizes to CO2 over time. In effect, that means that keeping the same number overall of heads of cattle does not increase global warming dues to methane or CO2 since the methane they produce was fixed from atmospheric CO2. There may be global warming caused by CO2 emissions from cattle farming due to fossil fuel use, particularly feed production, but that's…

It would be if we didn’t have a billion cattle on the planet and climbing. There’s a cow out there for every 7 people or so and if we make more people they’ll make more cows.

Cow methane is on the order of human population, so it matters.

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

#352

Post by acdha » Sun, Apr 23, 2023, 5:08 PM UTC

revelio wrote: post #335

acdha wrote: post #303

Earlier quoted context omitted.

If you want to talk about predictive power, let’s look at the first IPCC report from 1990. That had estimates which we now have data to judge them against, and have held up well: https://arstechnica.com/science/2012/12/ipccs-climate-projec... Similarly, Dr. James Hansen (director of NASA's Goddard Institute) testified before Congress based on his 1988 study predicting global warming and his numbers were very close to…

As the Ars article makes it clear, the predicted range of temperature change was extremely wide, 0.35 to 0.7 degrees by now even if you allow for the re-scaling to a shorter time period, yet actual change was at the very lowest point of that uncertainty interval. That by itself doesn't tell us that they understand the climate though. Remember that previously they were extrapolating a cooling trend into an ice age. An…

It’s not news that scientific consensus becomes more precise over time. The point was simply that scientists have a good track record of making accurate predictions decades out, which is quite the contrast of how deniers have flitted from wrong prediction to wrong prediction. Don’t feel bad for them, however — they get paid a lot better than climate scientists do and are probably old enough to miss out on the worst of it.

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

#353

Post by BlueTemplar » Sun, Apr 23, 2023, 5:15 PM UTC

xyzzyz wrote: post #70

djleni wrote: post #56

Earlier quoted context omitted.

Could you explain further? How does: > reducing methane emissions won't change a thing, compared to CO2 emissions. Follow from: > once methane emissions reach a steady level

Methane in atmosphere today is at 2 ppm, carbon dioxide is at 420 ppm. If methane is 20 times more potent, this implies that atmospheric methane is equivalent to 40 extra ppm of carbon dioxide. 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…

Where did you get the idea that most of the methane is from natural processes ? (Same for people that seem to think that most of anthropogenic ones are from livestock?)

Also some of the "natural" causes are suspect now, since they include things like permafrost thaw, which itself is caused by warming...

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

#354

Post by BlueTemplar » Sun, Apr 23, 2023, 5:23 PM UTC

iamthemonster wrote: post #220

gonzo41 wrote: post #160

Earlier quoted context omitted.

I'm more worried about untracked CH4 leaks from coal mines and LNG projects. Which dwarf farm emissions. Cow's are just part of the problem. The real threat is the LNG industry.

Methane emissions from oil and gas are enormously variable depending on what kind of upstream production facilities you have. Norway's methane emissions from oil and gas are negligible, and a couple of orders of magnitude better than the worst offenders, which are Russia and the US. Why the US? Shale gas is based on an enormous number of gas wells with a short lifetime each. It's not economical to provide power and c…

And then US tight oil is also suspect of being basically a scam : AFAIK this industry has had maybe a couple of quarters in the green, so, like with corn biofuel, the resulting energy is likely to end up negative (not even counting the pollution!) - basically Wall Street using cheap Quantitative Easing money, while leaving someone else will the bill once the music stops pumping ?

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

#355

Post by smolder » Sun, Apr 23, 2023, 5:28 PM UTC

codethief wrote: post #291

dataflow wrote: post #234

Earlier quoted context omitted.

> Methane naturally turns into CO2 in the atmosphere 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…

> It's kind of really, really important how high that "steady level" is and how fast we'd reach it though, no? (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 r…

Fossil fuels are used to make fertilizer on a massive scale as well as power a lot of equipment used, so agriculture is currently a piece of the fossil fuel problem.

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

#356

Post by BlueTemplar » Sun, Apr 23, 2023, 5:29 PM UTC

throwawaymaths wrote: post #104

it_citizen wrote: post #44

Earlier quoted context omitted.

The other big difference is that methane stays only around 12 years in the atmosphere compared to centuries for CO2.

This is so confusing to me. Iirc decades ago the rationale for methane being worse is that it stayed along longer. Now we know better from isotope studies (there's probably atmospheric bacteria breaking it down). The IR absorption spectrum of methane is way way weaker than CO2. (I have taken one myself in advanced pchem lab. This also makes sense b/c CO2 has a higher interatomic dipole moment and c-infinity symmetry…

Like TFA says : it doesn't end up in the same place in the atmosphere ? (A little bit like Ozone is bad to have around us, but extremely important in ~high (?) atmosphere?)

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...)

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

#357

Post by BlueTemplar » Sun, Apr 23, 2023, 5:33 PM UTC

matthewdgreen wrote: post #347

revelio wrote: post #329

Earlier quoted context omitted.

Such dangerous feedback loops are conjectured but not actually a threat. It can be proven with historical evidence like this paper, which shows that during the Roman times it must have been much hotter than today, like somewhere between 3-7 degrees hotter, based on the discovery of bison fossils in the Alps. This is well beyond the level climatologists claim would cause runaway feedback driven global warming and mass…

This sounds like a bunch of irrelevant nonsense. Not sure why you would post it.

It's not irrelevant, but there's a lot of extra information that he is leaving out... other variables ? rate of change ?

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

#358

Post by radford-neal » Sun, Apr 23, 2023, 5:36 PM UTC

machina_ex_deus wrote: post #297

dataflow wrote: post #234

Earlier quoted context omitted.

> Methane naturally turns into CO2 in the atmosphere 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…

The narrative is very misleading. 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…

"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."

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.

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

#359

Post by fooker » Sun, Apr 23, 2023, 5:36 PM UTC

adammarples wrote: post #278

fooker wrote: post #233

Earlier quoted context omitted.

> If you have strong scientific arguments, it does not matter even if the whole world is against you. That’s a nice idealistic thing to say. Academia has shown this to be false again and again. Most groundbreaking ideas or arguments which go against the current wisdom get buried in the best case, and the proponents scorned and driven out of research in the worst case. It has been like this since the beginning of orga…

According to your logic then, science should not have been able to advance at all from the very beginning

There’s a cynical notion that science advances one funeral at a time, attributed to Max Planck.

https://en.wikipedia.org/wiki/Planck%27s_principle

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

#360

Post by stametseater » Sun, Apr 23, 2023, 5:50 PM UTC

upsidesinclude wrote: post #230

stametseater wrote: post #170

Earlier quoted context omitted.

Specifically with respect to the methane cow farts, yes. That carbon comes from their plant diet (be it grass in a field or grain in a feeding lot), and the carbon in those plants came from the atmosphere. This isn't counting the fossil fuels the industry also burns, or the carbon released during the production of fertilizers used when growing that feed. But the carbon in the feed itself all comes from the atmosphere…

What about when seaweed is added to the feed which reduces methane emmission by 70%? The numbers that go into these approximations are not reliable and that's the problem with trying to have some exacting figure 20-28 and use that to create policy. Which is why we can know that it is just about creating policy.

Seaweed in a cows diet either: increases the CO2 the cow emits, increases the mass of carbon the cow shits, or increases the mass of the cow. The carbon has to go somewhere. I don't know where it goes, but regardless of where it goes, there's no doubt about where it came from to begin with. Virtually all the carbon cows eat was pulled out of the atmosphere by plants.