Basically you are counting GHG emissions as anything emitting, but, you are actually discounting the fossil fuel perspective which is heavily utilized for one, but not the other.
This data is also being based on comparing conventional produce raising vice feedlot style farming
> to put these figures into perspective, when combined with the fact that the average household consumes around 5 kg of food per day (29), average final delivery of food is 1640 km (1020 mi), and the total supply chain requires movement of 6760 km (4200 mi). Food groups vary in these average distances from a low of beverages (330 km delivery, 1200 km total) to a high of red meat (1800 km delivery, 20 400 km total).
and is heavily biased based on over-generalization which does not apply to many types of food production, as this assumes heavy fertilization, grain-feeding, etc.
> We estimate the average household’s climate impacts related to food to be around 8.1 t CO2e/yr, with delivery “food-miles” accounting for around 0.4 te CO2e/yr and total freight accounting for 0.9 t CO2e/yr. To put these figures into perspective, driving a 25 mi/gal (9.4 L/100 km) automobile 12 000 miles/yr (19 000 km/yr) produces around 4.4 t CO2/yr. Expressed in this manner, a totally “localized” diet reduces GHG emissions per household equivalent to 1000 miles/yr (1600 km/yr) driven, while shifting just one day per week’s calories from red meat and dairy to chicken/fish/eggs or a vegetable-based diet reduces GHG emissions equivalent to 760 miles/yr (1230 km/yr) or 1160 miles/yr (1860 km/yr), respectively. Shifting totally away from red meat and dairy toward chicken/fish/eggs or a vegetable-based diet reduces GHG emissions equivalent to 5340 mi/yr (8590 km/yr) or 8100 mi/yr (13 000 km/yr), respectively. Which of these options is easier or more effective for each climate-concerned household depends on a variety of factors, though given the difficulty in sourcing all food locally, shifting diet for less than one day per week may be more feasible.
> Within food production, which totaled 6.8 t CO2e/household-yr, 3.0 t CO2e(44%) were due to CO2 emissions, with 1.6 t (23%) due to methane, 2.1 t (32%) due to nitrous oxide, and 0.1 t (1%) due to HFCs and other industrial gases. Thus, a majority of food’s climate impact is due to non-CO2 greenhouse gases. Nitrous oxide (N2O) emissions, mainly due to nitrogen fertilizer application, other soil management techniques, and manure management, are prevalent in all food groups but especially in animal-based groups due to the inefficient transformation of plant energy into animal-based energy. Methane (CH4) emissions are mainly due to enteric fermentation in ruminant animals (cattle, sheep, goats) and manure management, and are thus concentrated in the red meat and dairy categories.
Similarly, other of these are all about dense feedlot operations
>We obtain animal feed requirements using the database from Herrero et al. (2013). This data set provides feed requirements for 30 world regions, which are mapped to the country level. Aggregated feed concentrate requirements per animal production system are distributed into individual crops, such as oil crops to rapeseed and others, based on feed crop consumption statistics (Food and Agriculture Organisation of the United Nations FAO, 2017). For consistency, feed use numbers from Herrero et al. (2013) are rescaled to match country-level feed use totals in FAOSTAT 2009–2011 (Food and Agriculture Organisation of the United Nations FAO, 2017). Feed crop emissions are then added to the consumption emissions of animal products.
As I have worked on a ranch like this that did not regularly use fuel, did not fertilize, basically grass pastured cattle, I found this material to be incredibly skewed. Maybe it is accurate talking about feedlot commercial cattle production. Maybe.
For smaller organic pastured husbandry that is not fuel intensive, and not grain fed, I don't find this to be true.
I do know the source of much of the cattle I consume. Given my location, I can also tell you that much of the produce where I shop is from at least >~2300 miles distant
Consequently, I call into question much of the data you provided, as an example of over generalization and data skew. I doubt this was intentional, since the articles didn't even suggest it was possible to eat anything meat based in a green manner. What Chutzpah!