A locavore is someone who tries eat foods that are mostly grown locally, like within 100 miles from home, but in much of USA, local agriculture is cattle ranching. Beef cattle.
Cattle grazing is a lot of what one sees within 100 miles of towns in places like eastern Montana. Not the best place to grow tomatoes, but cattle can graze. Problem is, cattle create methane which is a greenhouse gas. One recommendation for reducing greenhouse gas emission is to eat less beef. That might mean being less of a locavore for folks living in the vast areas of USA where cattle ranching is easier to do than growing, say, avocados.
Maybe beef isn't all bad. I hear that folks are working on modifying the cow's digestive tract to create less methane. Science can come to the rescue.
Meanwhile, there are many reasons to increase fruits and vegetables in our diet while reducing beef consumption. Health reasons as well as the global warming worries. In winter, that most likely means food being shipped from distant places like southern California.
Some people try growing tomatoes here in Bellingham, WA. but our summers are a bit too cool and cloudy. The slugs get them. We just aren't the best place for tomatoes, except maybe in hothouses. Some years, people have good tomatoes, but it seems rare.
Maybe we can have a diet of kale in the winter. Kale is nice, but might get boring after while.
Shipping from distant places creates greenhouse gas as well. Trucks, rail and so forth. Hopefully this isn't as big of an emitter to greenhouse gas as the driving that average Americans do each day.
Being a locavore may not do that much for reducing global warming. Eating less beef does more. Also figuring out how to live without driving, or at least less driving. Possibly living near the bus line or a bike path.
Buying local has some advantage for supporting local business and farming. Also increasing one's social life knowing the producers and meeting folks at places like farmer's markets.
Speaking of cows, I love locally produced Twin Brooks Dairy with it's returnable glass bottles. For some reason, it seems to taste better. I often start my day with their chocolate milk. It's my version of morning coffee.
I don't drink coffee. My reason for not drinking coffee is not because it doesn't grow around here. I just never learned to like the flavor.