[robin_reala]

If you eat meat once per day and you reduce that to once per week you’re consuming 86% less meat. If you eat it once a month you’re consuming 96% less meat. You don’t necessarily need to go full vegetarian or vegan to have a major affect on your diet.

[KozmoNau7]

And if you cut out red meat from your (reduced) meat consumption in favor of poultry or sustainably raised/caught fish, that also significantly reduces your food-related environmental impact.

[WorldMaker]

Eliminating beef alone can be huge in eliminating the greenhouse gas footprint of your diet (especially when consider methane in addition to simply carbon footprint). A somewhat, relatively distant, second after that is pork. Then dinosaurs, and fish (in roughly that order) are all basically tied at a, relatively, distant third in greenhouse gas output.

In addition to sustainably raised/organically farmed/etc, local sourcing can matter for carbon footprint (what you save in the carbon output of the farm itself you gain again in cross-country shipping carbon).