As I sat down to a massive burger a few days ago, I pondered about how my life has changed in regards to food. 

Gone are the days of guilt-free eating. Where once upon a time my burger decisions were limited to how many I thought I could cram into my belly at a sitting, now the following questions always pop up:

My head says: "Think of the environmental impact - all that deforestation, all those emissions!"
My heart says: "Think of the poor animals"
My stomach says: "Think of the taste - Buy one, no two, NOW.. and another for a snack later on!"

The end result is usually some sort of compromise.

While I've certainly made some headway in reducing meat consumption and found some decent mock meat products as substitutes, I'm still a long way off vegetarianism. 

But even a vegetarian or vegan diet has its pitfalls in relation to environmental impact and greenhouse gas emissions.

For example, what has the least carbon emissions   - a pound of out-of-season strawberries grown on a factory farm thousands of miles away or a pound of chicken that has come from your back yard flock that are fed on kitchen scraps and whatever else they can find in your garden? Or what about between the free range eggs from a local farm compared to the peaches from another country?

I'm sorry to say I don't have the definitive answer, they are just examples to point out the whole food carbon footprint issue isn't as cut and dried (or boiled, roasted or steamed) as it may seem; nor is it just a case of pitting a meat based diet against a plant based one.

However, in the interests of gaining a general idea of the carbon footprint of various foods for comparative purposes; below is some information gathered from around the web.

Single cheeseburger - 7 - 14 lbs CO2 (Source)
Pound of lamb - ~ 16 lbs CO2 (Source)
Pound of beef - ~ 15 lbs CO2 (Source)
Pound of pork - 6.75 lbs* CO2 (Source)
Pound of chicken - 3.37 lbs* CO2 (Source)
Pound of wild tuna - 4.5 lbs* CO2 (Source)
Pound of wild-caught shrimp - 2.7 lbs (Source)
Pound of wild salmon - 0.06 lbs (Source)
Pound of hothouse tomatoes - ~ 9 lbs CO2 (Source)
Pound of potatoes - ~ .4 lbs CO2 (Source)
Quart of milk - ~ 3 pounds CO2 equivalent (Source)

* Emissions in relation to feed only.

I'm sure you've seen similar lists around but something that many of them don't point out, and it's certainly worth reiterating - it's not just the food, but where it comes from (food miles), how it's grown, processed, stored and cooked; so take the above with a grain of salt (or a squirt of ketchup if you prefer) as all of the above figures are likely missing one or more element.

Here's a general rule of thumb - buy in-season, buy organic, buy local wherever you can (for example a farmers market, natural food cooperative or a CSA farm). If you can do all three in relation to a single food item, be it meat, fish, poultry, pork, fruit, vegetable, dairy or grain; you're well on your way to a diet with a much lower carbon footprint. If you're really keen to lessen it even more - grow your own food.