The planet’s food creates carbon emissions. Those emissions make for a tricky topic. There are all sorts of numbers tossed around. Due to the vast spread from the low end estimates to the high end estimates, the numbers cause confusion. Worse still, because of the discrepancies, people feel justified in selecting the number they most want to believe.

On this page, I’ll provide information from high quality sources, and share some ideas on why they make sense to me. This is not the only way to look at the issue. If you feel the information provided does not align with your world view and you want to find something that does, that is perfectly fine. I do not intend to convince, but rather simply to share one reasonable approach.

World, European, and U.S. Greenhouse Gas From Agriculture

The following charts provide a starting point for a discussion on greenhouse gas from livestock as well as the agricultural sector as a whole. First, providing a global perspective, the United Nations Environment Programme’s 2012 Emissions Gap Report lists agriculture at 11% of world CO2eq emissions.

2012 UNEP: United Nations Environment Programme

Next, let’s look at Europe, an area with high levels of industrialization. Eurostat, the official statistical office of the European Union, provides numbers from their European Environment Agency arm. These 2014 numbers put agriculture at 9.9% of European emissions.

Eurostat 2014: European Environment Agency

Finally on large area emissions, we move on to the United States. Not only is the United States highly industrialized, but the number of walkable cities approaches zero. Lack of walkability forces people into cars and trucks to achieve mobility, driving up non-ag emissions and reducing the percentage of agricultural GHGs. The 2014 U.S. Environmental Protection Agency numbers put agricultural emissions at 9% of the country’s total.


Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2014

Now that we have our starting point, lets really dive in. Easily the best way to reduce the CO2eq emissions from agriculture, would be for all of us to eat a vegan diet, but what would the impact be?

Vegetarians, Pescetarians, and Vegans Oh My!

The first section covers agricultural emissions as a whole. Livestock makes up a good sized chunk of that. To see how much, we have to take a look at the actual report on GHG emissions from agriculture. The first thing we see, in figure 5-1 is that the 9% number from the table is rounded up from 8.3%. The more interesting part comes in table 5-1. According to the EPA, agricultural emissions break down in the following manner.

The three sources highlighted in red make up 42% of agricultural emissions and 100% of direct livestock emissions. Using those numbers, livestock takes credit for 3.8% of U.S. CO2eq emissions. Thus using this simple form of estimation, we find that if 100% of the U.S. population were to adopt a vegan lifestyle, we as a country could reduce emissions by a percentage similar to 3.8.

I want to stress that this is a rough estimate. I did not start with 8.3% but rather the 9% listed in the EPA pie graph. I did not attempt to estimate replacement calories needed by vegans and vegetarians to survive on a non animal diet.  Nor did I estimate the reduction in animal feed that farmers would no longer need to grow. I’ll cover another estimate later on that will hopefully satisfy those concerns for the curious.

The bigger factor I want to address first is location based emission percentages.

“But I Don’t Live in the U.S. I Live in one Specific City”

It has been pointed out to me that each of us has our own emissions profile. It is true. Looking at averages does not tell the whole picture. There are a variety of ways we can attack that problem. One way is to actually calculate your carbon footprint. Then, spend some time learning about which areas you can change as an individual so as to make the biggest impact.

Anther way you can look at the issue would be to simply check out the average footprint for your zip code and assume yours is similar. Researchers at the University of California, Berkeley can help us out with that through their CoolClimate Network zipcode data. It really is cool. Take a look below at San Diego’s patchwork of varying emissions.

CoolClimate Network: Average Annual Household Carbon Footprint by Zip Code

Looking at the zip code map we can see high end emissions areas as well as some of the low end, but we need to go back to the calculator to see what the city and county look like as a whole.

The first page of the calculator allows us to take a look at individual cities and counties. Again, using San Diego1 as an example, these are the city and county results.

CoolClimate Network: Average Annual Household Carbon Footprint in San Diego: City and County

Looking at the graphs, one thing jumps out. San Diego, just like the rest of the U.S., drives… a lot.

The calculator gives exact amounts for each of the categories by hovering over the bar graph. Using the city as an example this is the comparison between tons of CO2e for car fuel and livestock emissions: Car fuel – 10.92; Meat – 2.74 tons; Dairy – 1.04.

Car fuel is responsible for 2.9 times more emissions than livestock emissions.

Average vs. Vegan Diet

I promised earlier to get back to the idea of how much an individual can cut their emissions when cutting out animal based food, aka going vegan. The answer is complicated. If you really want to find out more about the issue, I recommend you look at this thoughtful take on the subject by Shrink That Footprint. The conclusion they came to was that a vegan diet emits 40% fewer tons of CO2eq than the average diet. Based on my research, that seems about right. By combining their estimates with the U.S. EPA number of 9% you find a vegan diet lowers emissions by 3.6%, nearly identical to the earlier estimate.


Coming to some sort of conclusion about food emissions is hard. There are a thousand different ways to evaluate the data. Many of them conflict with each other and maintain sound internal logic. I tend to fall into the camp that separates sources of emissions fairly strictly into type. For instance, if a truck carries food from place to place, those fuel emissions for the truck should be considered transportation even though it was transporting agricultural products. In that way, when we separate many different forms of emissions into their respective categories, even when they could could conceivably be lumped into agriculture, we end up with a clearer picture of the world.

There are some researchers who would prefer to see agricultural emissions labeled with numbers in the high teens or low twenties. It is not hard to see how that would be possible. Simply by aggregating all possible sources of greenhouse gas output that is even marginally related to agriculture, those numbers materialize. However, if we do that, our image of the world becomes less crisp. We end up lost when trying to determine a most effective course of action.

There are lots of ways to reduce greenhouse gas. Eating fewer meat products or going vegan should absolutely be a consideration. Let’s just not miss the forest for the trees. That way, many generations from now, we still have both the forest and the trees.


  1. If you do not live in San Diego, make sure to check out your own region. San Diego home energy use is nearly non existent compared to the national average.