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omgJustTest

Stupid question: How much is this actually contributing to climate change?

Any climate scientists who make active predictions about how much we don't know?

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> Methane is more than 25 times as potent as carbon dioxide at trapping heat in the atmosphere

It's a pretty potent greenhouse gas.

https://www.epa.gov/gmi/importance-methane

Methane is a much more potent greenhouse gas compared to CO2, but also stays in the atmosphere much less long (on the order of a few decades).

The way methane "exits" the atmosphere is by becoming CO2, so it's strictly worse.

CO2 plus H2O (water vapor is also a highly potent greenhouse gas).

Methane becoming CO2 means it also produces H2O + a lot of heat, correct? Enough heat to use it as energy source for example.

Yes, biogas is primarily methane, and it's one possible energy source that can be (is?) used while transitioning away from fossil fuels.

When methane is released, each molecule casues 120x more warming than a CO2 molecule. As it decays (with a half life of ~10 years), it falls exponentially towards a floor of 2-4x worse than CO2 (it's 4x after 100 years and continues to decay from there). This is called Global Temperature Potential (GTP).

Even after 50 years, it's "only" 10x worse than CO2.

GWP is the average for all years, compared to CO2. For methane, most of this is contributed within the first 20 years after release. GWP is primarily useful for estimating the effect of constant steady state emissions. For instance, if we emit both methane and CO2 at constant rates from now to 2122, the heating from the methane is about 25x worse than from CO2. (CWP100=~25). (calculating this gives the same integral as averaging over 100 years).

However, if we're not looking at constant emissions, but instead large bursts where all the gas is released at once, it makes more sense to use the GTP curve.

Here is a nice plot that visualizes this: https://pubs.rsc.org/image/article/2018/EM/c8em00414e/c8em00...

Edit: strictly speaking, the above reasoning assumes the Earth cools rather quickly. Actual cooling once heat has been trapped can be 10-20 years, however, meaning the maximum temperature is reached about 10 years after the release, and it will take 20+ years for all the heat to escape Earth after the methane itself is gone.

https://pubs.rsc.org/image/article/2018/EM/c8em00414e/c8em00...

The 25x number is already accounting for the fact that methane doesn't stick around as long. It's based on 100-year GWP calculations [1]. If you look at shorter timescales methane is relatively much worse.

[1] https://www.epa.gov/ghgemissions/understanding-global-warmin...

As of 2015 it was estimated that methane made up 16% of the human contributions to global warming [0] So, significant but by itself not necessarily worrying.

However, there are a number of other factors that do make methane particularly worrisome. First, the concentration of methane in the atmosphere is going up much faster than CO2, this despite the fact that it decays into CO2 after about 10 years. Further, the higher the concentration of methane the slower its rate of decay, so it stays in the atmosphere trapping heat for longer.

Finally, and most worrisome, there appears to be a feedback loop with warming and methane release from permafrost.

[0] https://www.c2es.org/content/international-emissions/

According to the article, it lasts shorter time in the atmosphere compared to CO2.

> Since methane only lasts in the atmosphere for about ten years, compared to the centuries that carbon dioxide sticks around, reducing methane emissions could contribute to slowing global warming sooner,

Worth mentioning that CH4 ultimately turns into CO2.

At which point it reacts with ozone to form carbon dioxide and water. It's like saying the best way to destroy water is by freezing it.

Scientists tend to talk about greenhouse gases' global warming potential (GWP). A common figure used for methane is it has the GWP 20x that of CO2 over 100 year period. This takes into account that the methane at first traps a lot of heat and then it breaks down to CO2 and traps less heat.

Another consideration is that as the concentration of methane in the atmosphere rises the rate at which it breaks down slows.

The answer is actually not that easy to find when searching for less than 5 minutes.

The amount of CO2 in the atmosphere is apparently 440 ppm. CH4 (methane) is 1.85 ppm.

At identical concentration levels CH4 is 84 times more impactful greenhouse effect than CO2 over the course of 10 to 20 years and 28 over 100 years. So it should be about 35% of the global CO2 effect short term (which is not the total but close, probably ?), so highly significant. Curiously the number that I found is around 10-20% so either my numbers are wrong or other graphs I found use confusing units.

440PPM?

Yikes: https://news.ycombinator.com/item?id=12608421 seems like yesterday

It looks like if methane emissions were completely capped, we would still have above normal temperatures for decades before 20th century temperature norms were restored.

Who would be best to explain that in laymen terms?

Organics may offset some co2, so rainforest regrowth in brazil and other largescale projects may manage the aftereffects better.

Methane is a very strong greenhouse gas. But the upside is that it doesn't stay in the atmosphere for long. The half life of it is something like 9 years.

At which time it turns into CO2 which stays around longer, and water which I believe is a more potent greenhouse gas than either

Water falls to the earth as rain

warmer atmosphere == higher capacity to hold water vapor.

Something like 90 or 95% of the greenhouse effect is from water vapor. The only reason we really care about atmospheric CO2 is because we think that it triggers more atmospheric water which is the real driver of global temperature change.

Would it be ecologically responsible to set these leaks on fire?

Depends on who you ask. Today it's tomato soup and epoxy, tomorrow it's C4 and a cell phone. It won't be long before we have conversations about nationalizing fossil fuel companies.

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