If you don’t want to give up meat right away, at least consider stopping beef. One pound of beef is roughly equal to 8 pounds of pork, 10 pounds of chicken, and 20 pounds of tofu in CO₂ emissions.
One is co-production of other materials -- wool is another desirable material.
Another is optimizing land use. Some land isn't suitable for row crop agriculture, but can sustain grazing. There's also land we're irrigating for row crop agriculture right now from aquifers we really shouldn't be; converting it back to grassland and grazing on it would let us recapture some of the lost calories.
Then there's un-optimizing the food chain. From a food-per-acre standpoint we should be primarily subsisting on soy and whichever of corn, potatoes or rice grows best in the local soy & climate. Even if we are going all in on minimizing land usage, however, we don't want to produce exactly as much food as we need, because crops fail and famines are bad. You can aim to overproduce a little year to year and maintain a surplus of storage to cover the bad years, but you can't just cover the average bad year. You need to cover the worst years possible happening several years in a row, you need to be covering once-in-millennia bad luck. So you need to overproduce enough that you don't expect some of it to ever be consumed by humans.
So you need something to do with the extra corn you produce, besides feed it to people, that you can rapidly cut back on in case if crop failures to return food back to the supply. One option is ethanol, and another is livestock -- feed your surplus grains to livestock, and then eat them instead. If you have crop failures, you cull the herds, which frees up their feed stocks for human consumption, as well as adding the extra meat calories to the supply. (And this even happens somewhat automatically with market forces -- farmers are always arbitraging grain prices against meat prices, and a spike in grain prices will lead them to sell off livestock as they become less profitable, which will in turn depress meat prices further.)
Invasive cattle grazing on "worthless" land is a trope that's not true. Especially in the US west, we have seen massive ecological destruction at the hooves of cattle. They are not bison. They do not graze the same. The plants they consume do not regrow the same. They introduce a ton of issues.
Jon Muir called cattle, and other livestock, "Hooved Locusts", because of how they destroy the land.
The latest research is that we should absolutely be removing cattle from these "worthless" lands. We are still discovering how these lands work and we are finding so many benefits we had no idea existed.
We gimped nature and now we call that gimped version "how it's supposed to be". We use culture and heritage, "the western way of life", to perpetuate the systemic destruction.
But this trope of "white people decide the land is worthless" has a long history of being used to exploit the land/people for short term gain. Cattle grazing is a form of land theft. Destroying the land/ecosystem so people can't use it they way they have was, and still is, a form of land theft.
Also, the US west is getting so dry that cattle can't find enough grass so we do what? We pull water to grow grass in the desert so we can feed those cattle that are on "worthless land". Thereby making the issue worse. But are cattle ranchers and alfalfa farmers gonna give up their water? Ha! That's an affront to the Cowboy Way Of Life! We need cheap beef and stetson hats cuz this is Murica!
- Pork (8 lbs): 3.63 kg (3,629 g)
- Chicken (10 lbs): 4.54 kg (4,536 g)
- Tofu (20 lbs): 9.07 kg (9,072 g)
One kilo of beef is roughly equal to 8 kilos of pork, 10 kilos of chicken, and 20 kilos of tofu in CO₂ emissions.
I'm gonna cook some beef for dinner tonight :)