Much Depends Upon Dinner
A climatarian diet is different.
When my wife Kelly saw me taking a photo of her lovely gnocchi, she said “I could have left the prosciutto off it for the picture!” But in fact, it wouldn’t have made a lot of difference. When you look at the carbon footprint of various foods, ham products actually have a lower carbon footprint per 1000 calories than the ricotta cheese inside the gnocchi.
As the chart from Our World in Data demonstrates, beef is the big problem. Chicken, cheese, milk, and pork are all pretty close together. Fish is slightly worse, eggs slightly better, but the real deal is to keep away from red meat, shrimp (from the transport) and hothouse tomatoes (from the natural gas.)
That’s why a vegetarian diet that has a lot of dairy in it is not great, a vegan diet rich in out-of-season vegetables is problematic, and everything south of bananas, you can eat as much as you like from a carbon point of view.
I wrote a much longer piece about this on treehugger, where I ended the meal:
“I feel it necessary to conclude by noting that lowering one's carbon footprint isn't the only reason to change one's diet; there are also solid ethical reasons for becoming vegan, Eating less meat is said by many to be healthier, and eating less definitely is.”