Comment by manfredo | Hacker News Reader

Comment by manfredo | Hacker News Reader

Parent Full thread

Statistics on how much CO2 something emits can vary wildly. For instance, meat consumption has high CO2 emissions when you include the CO2 emitted by transporting grain to feed animals. But most typical studies would include that under emissions due to transportation. Hence why you can have some studies claiming meat accounts for a double-digit percentage of emissions while others claim that all agriculture contributes to ~3% of emissions.

The citation for this claim doesn't seem very robust. It links to the Ellen MacArthur foundation website, but just to the front page. After some of my own Googling it looks like it's coming from this publication [1]. This study drew up some estimates on the amount of textiles produced and discarded as well as a simple conversion of 4.7 Kg of CO2 for every Kg of textiles produced. The source for this ratio of CO2 to kilogram of textiles simply says "McKinsey Analysis"/

1. https://www.ellenmacarthurfoundation.org/assets/downloads/pu...

I’ve always wondered how much standardisation there is in reporting these types of numbers, particularly with regard to countries, albeit not enough to actually look in to it.

Say Australia digs up some coal, ships it to China, it’s used to power factories and smelters to produce goods, then those goods are shipped to and used by Americans. Is there consensus on who the pollution from burning coal gets tied to? Or does it vary per report and article?

It gets tied to China, for better or worse.

It goes to China, because it is the one that can change it. But that's when you're looking at the output of countries. What you could also do is look at the output of individual persons, and then you could more easily attribute the CO2 to the American.

Sustainable energy without the hot air does this, it's a great book though I've heard it's somewhat outdated now.

The analytic approach is great, but the numbers are very out of date.

It depends on what type of accounting is being used. If it’s a production-based accounting then they’ll be attributed to China. But if it’s a bottom-up, consumption-based accounting then they’ll be attributed to the consumer in the United States.

It’s great that both approaches exist, because they surface different conclusions. If you want to see where the actual emissions are being emitted, or what “industry” they’re from, then the production-based accounting will give you that. If you instead want to see what different consumer-level behaviors are responsible for most emissions then you’ll need a consumption-based accounting.

That duality is what makes it hard for people to grok carbon accounting estimates sometimes.

These different sources are classified as Scope 1 2 and 3:

- Scope 1 emissions are direct emissions from owned or controlled sources. - Scope 2 emissions are indirect emissions from the generation of purchased energy. - Scope 3 emissions are all indirect emissions (not included in scope 2) that occur in the value chain of the reporting company, including both upstream and downstream emissions.

So grain purchased and shipped to the animals is measured under Scope 3. Powering the lights and machinery on the farm is Scope 2.

It's tricky and inexact to do GHG accounting, but the same methodology and emissions factors are used everywhere so at least it's comparable between companies and products.

About meat specifically -- one has to be careful when counting all greenhouse gases versus just CO2, and pure quantity of gas vs. effect on global warming.

Cattle produces a lot of methane, which has a very powerful greenhouse effect, a lot more powerful than CO2. So while it does not contribute to CO2 emissions that much, it contributes to the greenhouse effect proportionally a lot more.

CO2e is standard when talking about GHG which takes this into account.

Oh yeah, I remeber also driving once next to a large farm with cows, it's crazy how much of the gas they produce.

got some downvotes, but I guess those people never experienced, you can close air circulation in your car and still smell it, it's that bad.

The methane has lower cumulative impact and is a closed loop where it gets recycled over time. [1]

[1] https://onezero.medium.com/cow-farts-are-not-the-problem-f57...

Also an interesting study compared what people bought who didn't buy meat, as vegetarian diet tends to be cheaper too. This brought the carbon difference to within 2%. I can't find it but think it was from Swedish researchers.

Reply on news.ycombinator.com