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Comment by tassl | Hacker News Reader

> Livestock agriculture is the leading driver of climate change AND biodiversity loss.

I am pretty sure that's not correct, not even close [1]. Transportation is the main driver of gas emissions (28%) followed by electricity production (27%) and industry (22%). Agriculture (livestock and crop) is <10%.

In most countries, livestock can graze in areas where cultivations cannot happen (Australia is a good example iirc) and can help with soil health.

> Additionally, if we would let nature reclaim the land that's currently used for livestock agriculture, it has the potential to capture >100% of the CO2 emissions until 2050.

Most of the food livestock consume are leftovers of human-grade crops. So we would still "need to" have that cultivations going and throw the leftovers anyways. Or most likely some company would find a way to feed humans that.

https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emis...

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According to this[0] Our World In Data article, which is based on 2018 data, livestock (including fisheries) produces about 15% of all emissions, assuming that animal-based products account for about a third of the supply chain costs of the food industry:

Total food emissions: 26%

Direct livestock + fish: 31% of that 26%

Due to livestock land use: 16% of that 26%

Due to crops for animal feed: 6% of that 26%

Due to supply chain (1/3 of total): (18/3)% of that 26%

Total: ((31+16+6+(18/3))/100)*0.26 = 15.34%

And according to this[1] Our World in Data article, transport makes up about 16.2% of emissions.

The analyses can differ depending on how far you "travel up the chain" of production, but it appears that transportation and animal agriculture are within the same ball-park, plus or minus 5% perhaps.

> Most of the food livestock consume are leftovers of human-grade crops.

This is incorrect. Most livestock feed is soy, and humans can and do eat soybean meal. About 98% of soybean meal is used for animal feed and only 1% is used to produce food for people.[2] For soybeans as a whole, only about 6% grown worldwide are turned directly into food products for human consumption.[3]

[0] https://ourworldindata.org/emissions-by-sector

[1] https://ourworldindata.org/emissions-by-sector

[2] https://www.canr.msu.edu/news/where_do_all_these_soybeans_go

[3] https://www.ucsusa.org/resources/soybeans

No, even if most of livestock feed was soy (I am pretty sure it was corn, but whatever), most of the food they are feed as dry matter is not edible by humans: https://www.sciencedirect.com/science/article/abs/pii/S22119...

I would like to see where that 98% really comes from, the links you posted talk about 70% (and most of that being consumed by poultry, not cattle). And even that seems excessive [1]. I would love to see a clear separation between the soybean. meal (leftover from oil and soybean grinding) and explicit feed grade soybeans.

[1] https://www.usda.gov/sites/default/files/documents/coexisten...

Globally, GHG emissions from livestock agriculture make up between 1/4 and 1/3 of all GHG emissions (depending on the source, but here's a good one: https://ourworldindata.org/environmental-impacts-of-food). And this does not take into account CO2 sequestered by land that is already converted to cultivated land (i.e. not natural vegetetation) - so the potential of additionally sequestering carbon is much higher.

That's right that Australia doesn't have a lot of natural forests, but even there natural vegetation is better at sequestering carbon than land that has been converted to be used for agriculture. But if you look at this map here [0], you'll see that Western Europe, South America, Southern Africa and South East Asia all have great potential to capture CO2 if we let the natural vegetation regrow.

> Most of the food livestock consume are leftovers of human-grade crops.

No it's not. Furthermore, from a protein and nutrition stand-point, the plants we grow today are enough to feed the whole world.

0: https://www.nature.com/articles/s41893-020-00603-4.epdf?shar...

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