So here's where it comes from.

现在介绍这些温室气体的来源
The carbon dioxide emissions are the things that we've talked about already,

我们已讨论过二氧化碳排放物
but the methane emissions come from rumen in animals,

甲烷则是由动物的瘤胃产生
I'll describe a little bit about

待会我将详细解释这些
what that means,

还有
and then the release of methane from animal manure,

甲烷从牲畜粪便中释放
and the amount of this out there is really remarkable.

而这些粪便的数量大得惊人
The nitrous oxide come from release from

一氧化二氮来源于
urine and manure from animals,

动物的尿液和粪便
vast amounts of these sorts of things.

而且其数量巨大
Just take a cow, for example, and

以一头牛为例
think about how big a cow is

想想牛有多大