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Comment by filleokus | Hacker News Reader

From where does the (extra) greenhouse gas emission come? The cow itself consume renewable feed (of course [1]). Is it the transportation of feed, production of clean water, random diesel tractor stuff? Maybe deforestation due to feed production?

[1]: Or is there feed where the carbon is taken from e.g petroleum somehow? Sugar is a hydrocarbon after all...

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The cow transforms the carbon from plants, originating from atmospheric CO2, into methane which has a GWP of 25, meaning its greenhouse warming effect is 25 times higher than that of CO2. So the net result of feeding plants to cows is an increase in global warming.

But the methane will oxidise down into CO2 in 8 years or something (according to Google). So essentially you pay the tax for the "GWP-bump"? It's resonable but maybe a bit hard (or at least non-obvious to me) to calculate fairly?

Methane has a GWP of 25 over 100 years (the standard period used for GWP) even though almost all of its warming effect takes place in the first decade. Unless you want to take a reference period on the order of a millennium, methane is always going to have a significantly higher impact compared to CO2.

You can find tables with values for a few different gases and periods on Wikipedia[0]

[0]https://en.wikipedia.org/wiki/Global_warming_potential

If its frontloaded, then it makes sense to keep this ace up our sleeve until temperatures become unbearable. Then at that time, we can cut methane for immediate relief, to flatten the temperature curve if you will. Doing it too early is pointless.

Cow digestion produces on average 220lb of methane per year which acts as a potent greenhouse gas.

https://www.ucdavis.edu/food/news/making-cattle-more-sustain...

Yeah, but how is the "net" greenhouse effect calculated? Over a long time period it should be zero:

Co2 from atmosphere -> Consumed by grass / grain -> Cow eats -> Methane released in atmosphere -> Broken down to Co2

Over a long enough timescale CO2 gets sequestered so the net impact over 10 million years is ~zero. However we don’t really care about geologic timescales.

20 years is a ‘long’ time period from a human perspective and it’s 80x worse over that timeframe.

I saw some numbers about 30x and 10 years, but yeah it's definitely an externality that should be taxed.

But if we have two situations (A) where 1 tonne of fossil Co2 is added to the atmosphere, from e.g fossil fuel and (B) where 1 tonne of renewable methane is added, from e.g cows, it doesn't feel obvious to me how to compare them.

(A) will increase the Co2 PPM / have a GH effect for centuries, if not thousands of years. So on any human timescale it's essentially permanent. This has a pretty clear price in many tax frameworks.

(B) will have a 30x GH effect for 10 years.

What's the cost of externality (B) compared to (A)?

You’re likely thinking of Methan’s global warming equivalent over 100 years which is 27-34.

(34) https://clear.ucdavis.edu/explainers/gwp-star-better-way-mea....

(27-30) https://www.epa.gov/ghgemissions/understanding-global-warmin...

As to how you weigh each it’s worth remembering that climate change often causes harm due existing infrastructure being ill suited to the new situation.

1m higher sea level rise 10,000 years ago would be irrelevant to us today because people would have built buildings based on the way things where. 1m sea rise in the future therefore is problematic because it renders infrastructure useless not because what the final sea level ends up being. Obviously some impacts are inherently harmful, but many things can be adapted to.

In America, it mostly comes from farm subsidies. Subsidies on feed corn and feed soybeans make it cheaper to buy feed than to grow it yourself. So, rather than grow feed on the same farm, fertilized with manure, farmers buy feed trucked in from neighboring states fertilized with chemicals, much of which is petroleum based, and discard the manure.

And, then there are the cow farts full of methane. Methane is apparently a much more potent greenhouse gas than carbon. I’ve heard for over a decade that there is some seaweed-based supplement that dramatically cuts methane from cows. But, I guess farmers have had no motivation to buy it yet.

The extra emissions come from several factors:

- cows need a lot of land. If you used that land for e.g. efficient crops instead (and if people ate that instead of all that beef) you would free up a lot of land which you could use for other things (say, plant trees for example)

- cows need to eat a lot of feed to produce 1 calorie of beef. It is much more efficient to produce 1 calorie of vegetables and let people eat those vegetables directly instead of having it go through a cow first

- cows emit a lot of methane

- deforestation to produce more feed (like e.g. soy) is indeed also a factor

Cows literally fart methane, a greenhouse gas an order of magnitude worse than carbon. There is no green way to mass produce beef and those externalities should be taxed. However, I know nothing about Danish agriculture so I don't know if this tax is fair and well thought or not, but industrial agricultural production of beef absolutely needs to be taxed.

Hmm, so you mean we should kill all cows then?

I can't tell if you're being tongue-in-cheek or not here, but yes. For many reasons, we need to dramatically and quickly reduce industrial beef and dairy production. The effects it has on climate change, the water and land usage, and the effect it has on antibiotic resistance are all reasons we need to stop immediately. Of course, we won't because people are selfish and myopic, but we absolutely should.

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