from producing 1 kilogram of some common foods.

In other words, it shows how much they contribute to global climate change.

Most fruits and vegetables are down here,

with relatively low emissions.

Poultry and eggs are a little further up.

Pig products are here.

Coffee and chocolate are a little higher.

But all of these pale in comparison to this food.

It's the worst thing we eat when it comes to global warming.

This is beef.

When you only account for the emissions that go into the processing, transportation, packaging,

and selling of a food product, the difference between these foods isn't so great.

When you add the emissions from growing and processing food for livestock, you can see

that animal products have higher emissions than vegetables .

But the real gap comes from these two factors:

the emissions associated with the farming process,

and the impact of land use change.

Coffee has such a big footprint because of

the fertilizers farmers use to grow it, which emit a lot of the greenhouse gas nitrous oxide.

The farming process also accounts for most of the disparity between cow and sheep products,

and everything else.

Cows and sheep have to digest food that most animals can't do as well,

like grass, and tough plant material.

Their stomachs are microbe-rich to help them do that through a process called

enteric fermentation.

The byproduct of this digestion is methane, a powerful greenhouse gas.

Some of those emissions come out this way,

but 95% come out the front.

If you've never heard one of these animals burp,

there's an endless supply of Youtube videos for your viewing pleasure.

"Really?"

"That was rude, sir!"

Jokes aside, though, methane is a huge contributor to climate change.

It's the second-most emitted greenhouse gas after carbon dioxide.

But it traps more heat than carbon dioxide.

Its global warming potential over 100 years is 21 times higher.

Among human-related activities, enteric fermentation

is the biggest contributor to methane emissions globally.

More so even than the methane emissions from burning fossil fuels.

And it's a big reason why the farming process related emissions for beef and sheep are so high.

The second reason is land use change.

Starting in the 1700's, the amount of land

developed for humanity's purposes started to skyrocket.

Only a tiny amount of this is due to our built environment, like cities, towns and other infrastructure.

A vast majority is for agriculture. And when you divide that up, you see that

land for grazing animals far surpasses land for growing crops.

Converting all that land to farms to make way for grazing or growing crops releases

the carbon that was once stored in trees, other plants, and the soil.

By contrast, nuts, and citrus fruit, and olive oil have negative land use emissions because

planting nut, and citrus fruit, and olive trees is reforesting cropland.

But chocolate has a lot of land use emissions because cacao farming results in tropical

deforestation in Southeast Asia, Africa, and South America.

And grazing animals take up a lot of space compared to crops. 80% of deforestation in

the Amazon rainforest, for example, is to make way for cattle ranching.

This is how many tonnes of greenhouse gases per-capita, we emit through all of our activities.

Changing our diet to exclude high-emission foods has the potential to reduce that by 28X00:04:02,420 --> 00:04:06,440 by both reducing emissions and reforesting land.

That's more than any other life change we could make.

A lot of food emissions are unavoidable. We have to eat.

But we do have a choice of what not to eat.