Livestock

[Tim illingworth]

Cows are vegan… so why are they so bad for the environment? Surly the grass they eat balances their breath and trumps?

 

[Lou]

Cows are vegan… so why are they so bad for the environment? Surly the grass they eat balances their breath and trumps?

How is eating grass good for the environment?
But its not just that - its the numbers.

"The Earth currently has about 19.6 billion chickens, 1.4 billion cattle, and 980 million pigs being raised as livestock. If you added them all up, they'd weigh more than humans and all other wild animals combined."
- These maps show where all the world's cows, chickens, and pigs are

 

[Jamie in Chile]

A lot of the food that cows eat - the majority I think is not grass - but industrially produced grain and other foods. Far from counter balancing emissions, it adds more. Cows fed on grass for their whole life are a minority.

And if most cows were grass fed it would take up a ridiculous amount of land which would devastate natural ecosystems and take land away from other human activities as well.

If you are interested in a more detailed answer, you can see the movie Cowspiracy.

 

[Lou]

A lot of the food that cows eat - the majority I think is not grass - but industrially produced grain and other foods.

Oh, yeah. That's right. after a few months most cows are shipped to the feed lot where they are fed a mixture of grains. Mostly corn.

 

[Graeme M]

That's a good question. The problem with animal agriculture isn't just enteric emissions from cattle, it is all of the processes related to industrial scale livestock farming. It is manure management, land use change, growing of grains to feed them and so on. Cattle are ruminants and they are the ones producing the enteric emissions. Chickens and pigs are monogastrics, so I do not think they cause those sorts of emissions. That said, it isn't the case that enteric emissions are a really BIG component of anthopogenic emission - I think beef cattle produce about 3.5% of all anthropogenic emissions on a CO2 equivalent basis while dairy cattle produce about 1.6%.

Also, it would be interesting to know how many ruminants there are globally now, compared to before there were humans. After all, while there are a lot of beef cattle, there are now far fewer deer, bison etc, so are we really generating THAT much more methane from cattle than would be the case without them?

 

[Lou]

There are some historical evidence that in the 1500s there were 30 - 60 million bisons.
Today there are something like 100 million cows.

Bisons and deer and the like are all part of a natural ecosystem that has been pretty much in balance for a really long time. There were fluctuations of their populations based on things like weather. But over the long term things remained in balance for a really long time. And although the world experienced climate change - it was nothing as rapid or as severe as what is going on now.

the contribution of live stock to global warming is debated but I think most scientists agree on 10%

 

[Jamie in Chile]

I think it's more like 15%-20% of greenhouse gas emissions but 20%-30% of all global warming when you factor in land use changes

but sources vary

I assume you mean all animals not just cows in which case 10% would probably have been one of the lowest estimates

 

[Lou]

Yeah, it definitely matters on what you are counting.
I've seen as high as 35%.
20% seems to be the most typical
and 10% maybe the lowest.

 

[Lou]

Ok, this factoid and reference just got emailed to me

Total emissions from global livestock: 7.1 Gigatonnes of Co2-equiv per year, representing 14.5 percent of all anthropogenic GHG emissions.
- FAO - News Article: Key facts and findings

 

[Graeme M]

Yes, that FAO reference gives us some useful information; it's where I came up with my earlier points above. The total of 14.5% represents all impacts from livestock activities which as I said earlier includes a wide range of activities and processes. The source notes that cattle (beef and dairy) produce 65% of that 14.5%. Overall, enteric emissions account for 39% of the 14.5%, which as I noted above means that beef cattle produce about 3.5% of global anthropogenic emissions (on a CO2 equivalent basis) and dairy about 1.6%. Enteric emissions from beef cattle are therefore quite small as a component of total anthropogenic emissions with the majority of emissions from the sector coming from other activities such as land use change, transport, manure storage and waste management etc.

While it is probably true that bison populations were far lower than current cattle population in the US, bison are rather larger animals. As well, deer and other ruminants may have had quite extensive populations. Given that in the rest of the world natural ruminant populations are very likely to be considerably lower today than in the past, I still think it is a stretch to say that enteric emissions from cattle are way out of balance with past emissions before we began grazing cattle at today's density. The addition to natural sources from processes such as those mentioned (eg land use change, manure storage etc) are where we see something out of kilter with any earlier "balance".

 

[Jamie in Chile]

The 14.5% figure seems to be perhaps the most commonly cited and respected figure.

However the actual indirect impact may be higher since cutting out that 14.5% of your carbon footprint by going vegan may lead to some agricultural land going wild or being used for tree planting or some other agricultural carbon capture, so if you allow that the true impact may be higher

I posted this once before: We can’t keep eating as we are – why isn’t the IPCC shouting this from the rooftops? | George Monbiot

 

[isaacrob181]

Mainly, Dairy cows and their manure contribute to climate change by emitting greenhouse gases. Poor manure and fertilizer management can degrade local water resources.