In developed countries, it's double that.

在已開發國家，量甚至翻倍。

Or about the same weight as an adult dolphin.

或者跟一頭成年海豚一樣重。

But experts now advise cutting down the amount of meat we eat, to help reduce climate change.

但專家現在建議我們減少食用的肉量，來幫助減緩氣候變遷。

So, here's a thought experiment.

接下來是讓我們開始思想實驗。

[What if the whole world turned vegan?]

[如果全世界人都吃素會怎麼樣呢？]

Around 15 percent of all greenhouse gasses emitted by humans are from livestock production.

約百分之十五由人類排放的溫室氣體是與家畜產業有關。

If we all became vegan, these emissions would be slashed.

如果我們全部都吃素，這類型的溫室氣體排放會銳減。

Eating meat takes up space, a lot of it.

吃肉會佔空間，而且是很多空間。

Around 80 percent of all farmland is dedicated to meat and dairy production.

約八成的農地貢獻給了家畜業與酪農業。

That's about the size of Europe, the U.S., China, and Australia combined.

而這大約是歐洲、美國、中國與澳洲加總的面積。

Meat and dairy typically provide 18 percent of our calories, but account for 60 percent of greenhouse gas emissions from agriculture.

肉與乳製品提供了我們所需熱量的百分之十八，但卻佔了農業溫室氣體排放量的百分之六十。

A report by the UN's climate body, the IPCC, recommends we all reduce the amount of meat we eat.

一個隸屬於聯合國的氣象組織，政府間氣候變化專門委員會，提出的報告建議我們減少吃肉的的量。

And also how much we waste.

還有我們所浪費的量。

The report found 8 to 10 percent of all global emissions are down to food loss and food waste.

報告發現在全球溫室氣體的排放量，有百分之八到十的量是因為食物損失還有食物浪費。

But not all meat is the same.

但不是每種肉類都一樣。

Large-scale farming of beef has a particularly high impact, and has been a big factor in the loss of the Amazon rainforest.

大規模養殖牛業對於環境有特別明顯的影響，也是造成亞馬遜雨林消失的一大因素。

When cows digest their food, they produce methane, a powerful greenhouse gas that's about 28 times more powerful than carbon dioxide over 100 years.

當牛消化食物，牠們會產生甲烷，一種在百年內比二氧化碳威力是溫室氣體的 28 倍。

And when cows burp, this methane is emitted.

當牛打嗝，這些甲烷就會釋放到大氣中。

One cow releases between 70 and 100 kilograms of methane every year, and there are around 1.5 billion cattle in the world today.

一頭牛一年平均排放 70 至 100 公斤的甲烷，而現今地球上約有 15 億頭牛。

But it's not that simple.

但事情沒有這麼單純。

A lot depends on how the meat is produced.

這跟這些動物的養殖方式有很大關係。

Most meat is mass-produced by large-scale industry, and this can come with a heavy environmental impact.

絕大部分養殖業是大規模經營模式下大量生產的，而這也為環境帶來嚴重影響。

But small-scale farming of animals can have a lower environmental footprint.

但小規模經營養殖業在環境留下較少足跡。

And sometimes, for example in the case of traditional grazing, it can be beneficial in terms of biodiversity.

有時候，舉例來說，以傳統放牧的模式可以為生物多樣性帶來好處。

Vegan alternatives can also come with their own problems.

但在素食者的替代食品方面也會面臨問題。

For example, large-scale production of soya can lead to deforestation, and almond production requires huge amounts of water.

好比說，大規模栽種黃豆會造成森林砍伐的問題，而種植杏仁需要大量的水。

But if everyone switched to a plant-based diet, it could bring several positive health benefits.

但如果大家都準換成以蔬食為基底的飲食，可以為人類身體健康帶來好處。

One study estimated that if everyone ate a vegan diet, with lots of fresh fruit and veg, around eight million deaths could be avoided around the world by 2050.

一個研究估計如果所有人都吃素，吃很多的新鮮水果和蔬菜，在 2050 年前有 800 萬人能免於一死。

There are no simple answers.

這件事沒有簡單的方式。

But if everyone were to change how they look at food, cultivate it, and eat it in a sustainable way, we could, potentially, change the world.

但如果所有人可以改變看待食物的方式、栽種它並以永續的方式食用它，我們可以潛移默化地改變這個世界。

Thanks for watching.

感謝收看。

Don't forget to subscribe and click the bell to receive notifications for new videos.

不要忘記按下訂閱還有小鈴鐺來接收所有新影片的消息。

See you again soon!

我們很快會再見的！