There are currently over 7 billion humans inhabiting the Earth and that value is increasing exponentially.

現今，地球上有超過 70 億人居住，而且一直呈指數增長。

So that has a lot of people wondering including me: "How many people can the Earth even hold?”

因此，這讓包括我在內的很多人都想知道：「地球到底能容納多少人呢？」

It's estimated that, by the end of the century, the human population will be over 10 billion.

據估計，到本世紀末，人口將超過 100 億。

And scientists are unsure whether this will be sustainable or not.

科學家們也不確定地球是否承受得住。

To see why, let's start off by talking about my favorite subject: food.

為了探討原因，讓我們先討論我最喜歡的主題：食物。

If you were to take all the land being used to raise livestock and put it on one continent, it would take up all of Africa.

如果可以把所有用來飼養牲畜的土地都放在一個大陸上，可以占據整個非洲 。

In fact, it would actually be greater than Africa--between 8 to 9 billion acres.

其實，它會比非洲還要大——介於 80 億到 90 億英畝之間。

And if we did the same thing for crop production, it would take up an area about the size of South America.

同樣的，如果換成是農作物生產的話，大約是整個南美洲的面積。

But, after a while, the soil in these areas will degrade, meaning its fertility decreases.

但是一段時間後，這些地區的土壤會退化，這意味著土壤肥沃度下降。

And it erodes, rendering it useless for growing crops.

土壤侵蝕使此地無法種植農作物。

And not only that, but scientists are unsure if farmers could even maintain their current crop yields due to changes in the environment.

不僅如此，科學家們無法確定在環境的變化下，農民們是否能維持當今農作物的產量。

See, the global average of carbon dioxide emissions per person is about 5 metric tons per year.

每年全球每人平均二氧化碳排放量約 5 公噸。

But for Americans, that average is closer to 17 metric tons per year.

而美國人的平均則是，每年將近 17 公噸。

And remember, this is per person.

而且記住，這只是一個人而已。

So, if we have about 3 billion more people living on this planet, and they all adopt a lifestyle similar to an American, the effects of global warming will be worsened even more.

所以如果我們有超過 30 億人口生活在這個星球上，而他們的生活方式都和美國人相似的話，全球暖化造成的影響會更加嚴重。

In fact, it's projected that the temperature of the Earth will increase by 2 degrees Celsius by the end of the 21st century.

事實上，預計到 21 世紀末，地球溫度將上升攝氏 2 度。

And with that increase comes more extreme weather conditions, which would inevitably disrupt food production.

隨著溫度的上升導致氣候變得更極端，無可避免地，它將會擾亂糧食生產。

So yeah, you know, not good.

沒錯，這很糟糕。

Now, this can be partially remedied by everyone adopting a vegetarian diet, and reclaiming the land to grow more crops instead of raising livestock.

現在，這可以靠每個人都吃素來補救，開墾土地種植更多的農作物而不是飼養牲畜。

But the crops won't be enough to feed an infinite number of people.

但這些農作物不夠養活無止盡增加人類。

In fact, some scientists predict that it would only be enough to feed 10 billion people.

一些科學家預測那些農作物，只夠養活 100 億人口。

And more than likely, most people won't switch to a vegetarian diet.

更有可能的是，大部分的人不會改吃素。

After all, bacon is a beautiful thing that exists.

畢竟，培根是多麼美好的存在。

And bacon on pizza, oh my God.

培根加在披薩上面，天啊。

But what about the amount of available water?

但可用水資源的多寡呢？

Humans are currently using up about 30 percent of the Earth's accessible renewable water supply, with the rest being used for agriculture.

目前，人類使用地球上約 30% 的可再生水資源於民生用水，而剩餘的則是用於農業用水。

And the water available to some people in countries like Ethiopia, Cambodia, and Haiti isn't even clean enough to drink.

有些國家人民的飲用水甚至髒到不能喝，像是衣索比亞、高棉和海地等。

So, the amount reaching humans would have to increase with an increasing population.

因此，隨著人口的增長，所需的水量就需要再增加。

So, to answer the original question: the Earth may be able to hold a large number of people, perhaps even over 10 billion.

那麼，回到一開始的問題，答案是：地球也許能容納龐大的人口，甚至可能超過 100 億。

But the quality of those people's lives would be much different than they are right now.

但到時候人們的生活品質一定會和現在差很多。

So how many humans do you think the Earth can hold?

所以你覺得地球能容納多少人呢？

Or do you think we're already there?

還是，你覺得已經到達極限了呢？

Let me know in the comments below.

歡迎在底下留言讓我知道。

Make sure you come back every Monday for a brand new video.

每週一敬請收看我們全新的影片。

As always, I'm Blocko and this has been Life Noggin.

老話一句，我是 Blocko，這裡是 Life Noggin。

Don't forget to keep on thinking!

別忘了要持續思考喔！