The math here is quite simple.

A single cow can produce around 250 to 500 liters of methane per day through belching and farting. Let's take an average of 400 liters/day. Methane is a potent greenhouse gas.

400 liters/day × 365 days = 146,000 liters/year.

Convert to kilograms (since methane’s density is ~0.656 kg/m³):

146,000 liters = 146 m³ → 146 × 0.656 kg = 95.8 kg of methane/year per cow.

Methane has a global warming potential (GWP) of about 28 times that of CO₂ over 100 years. So, 1 kg of methane is equivalent to 28 kg of CO₂ in terms of warming effect.

95.8 kg of methane × 28 = 2,682 kg of CO₂ equivalent per year per cow.

2,682 kg CO₂e/year × 1 billion cows = 2.68 billion metric tons of CO₂ equivalent annually.

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cpursley 8 months ago | parent [-]

Cool. Now compare cow farts to all other sources, that’s the only metric that matters.

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MattPalmer1086 8 months ago | parent [-]

A quick search shows that global c02 emissions are about 35 billion tons.

So the cow farts are a bit less than 8%. That isn't insignificant.

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idunnoman1222 8 months ago | parent | next [-]

You can actually reduce how much methane cows produced by changing their feed by like 80% or something

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cpursley 8 months ago | parent | prev [-]

And how much of a dent would reducing cow consumption by 25% make?

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MattPalmer1086 8 months ago | parent | next [-]

You said that cow emissions weren't significant (well, that it was "absolute lunacy").

Two people have provided rough calculations that show they do have a measurable effect.

What's your point?

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cpursley 8 months ago | parent [-]

My point is people should do the math and come to their own reasonable conclusion. Assuming these numbers aren't totally bullshit (see what I did there) this won't move the needle unless we cut out cow consumption 100% and cull all native herd animals.

Me? I think we can probably survive some cow farts as our ancestors who hunted buffalo and burnt down entire ecosystems doing so did. We should focus on the real solutions that will move the needle, like proper human-scale city design and nuclear power.

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insane_dreamer 8 months ago | parent | next [-]

A 2% reduction is absolutely moving the needle.

There is no silver bullet that's going to be a 25% reduction all on its own. The only way to win is a combination of changes each of which reduce emissions by a few percentage points.

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MattPalmer1086 8 months ago | parent | prev | next [-]

Knowing they alone account for over 1/20th of the climate change effect though is useful information.

Maybe there are other ways we could reduce their methane emissions short of getting rid of all of them.

I agree that other solutions are needed to properly address climate change though.

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cpursley 8 months ago | parent [-]

There’s a ton we can do before taking food off our children’s table.

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MattPalmer1086 8 months ago | parent [-]

I don't think anyone was talking about taking food off children's tables?

	▲	cpursley 8 months ago \| parent [-]
		Because that's exactly what reducing farming output does.

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neither_color 8 months ago | parent | prev [-]

I don't know enough about this topic but my question is what is the input to the 250-500l cow fart equation. What's being consumed to produce that much methane?

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insane_dreamer 8 months ago | parent | prev [-]

Hmm, lets see: 8% * 25% = 2%