Earth has been pummeled by asteroids, crashed into other planets, and frozen over several times.

地球曾被小行星撞擊，撞入其他星球，並多次被冰封。

Not to mention being ruled by all kinds of crazy life forms.

更不用說被各種瘋狂的生物統治了。

Sometimes it's a wonder that our blue homeworld has survived it all.

有時，我們的藍色家園能夠倖存下來，真是一個奇蹟。

But if we want to take a whirlwind tour of our planet's history, we'll have to start way back at the very beginning.

但是，如果我們想對地球的歷史來一次旋風式的旅行，我們就必須從最開始的時候開始。

Some 4.5 billion years ago, our Solar System began to emerge out of a dense cloud of interstellar gas and dust.

大約 45 億年前，我們的太陽系開始從一團稠密的星際氣體和塵埃雲中誕生。

This cloud collapsed into a swirling disk of matter that got hotter and hotter and hotter until hydrogen fused into helium.

這個雲團坍縮成一個物質漩渦盤，溫度越來越高，直到氫熔化成氦。

And just like that, our Sun was born.

就這樣，我們的太陽誕生了。

And baby Earth was on its way too.

地球寶寶也即將誕生。

After the birth of our star, all the matter on the farthest ends of the spinning disk began to clump together.

我們的恆星誕生後，旋轉盤最遠端的所有物質開始聚集在一起。

These clumps would be the seedlings for the planets and moons in our Solar System.

這些團塊就是太陽系中行星和衛星的幼苗。

As they accumulated more matter, they grew bigger and more spherical.

隨著積累的物質越來越多，它們也越來越大，越來越呈球形。

The clumps in the cooler regions of the Solar System were mostly made of ice, liquids, and gases.

太陽系較冷區域的星團大多由冰、液體和氣體組成。

Closer to the Sun, all the rocky material formed the inner planets like Mars and Earth.

在離太陽更近的地方，所有的岩石物質形成了火星和地球這樣的內行星。

This young Earth was incredibly active, volcanically speaking.

這個年輕的地球在火山方面異常活躍。

It spewed out gases like hydrogen sulfide, methane, and carbon dioxide.

它噴出硫化氫、甲烷和二氧化碳等氣體。

These gases made up the very first atmosphere on our planet.

這些氣體構成了我們星球上最初的大氣層。

Early Earth was constantly bombarded by large asteroids and comets.

早期的地球不斷受到大型小行星和彗星的轟擊。

And soon, Earth experienced an even more violent collision.

不久，地球又經歷了一次更加猛烈的碰撞。

Theia, a planet the size of Mars, slammed right into our young world.

忒伊亞，一顆和火星一樣大的行星，撞上了我們這個年輕的世界。

This epic collision threw chunks of matter all around Earth's orbit.

這次史詩般的碰撞將大塊物質拋向地球軌道的各個角落。

And then gravity bound them together into what we know now as the Moon.

然後，引力將它們結合在一起，形成了我們現在所知道的月球。

On this hot, early Earth, there were no oceans.

在這個炎熱的早期地球上，沒有海洋。

All water existed as gas.

所有的水都以氣體形式存在。

But 3.8 billion years ago, our planet cooled enough for water to condensate and become liquid.

但在 38 億年前，我們的星球冷卻到足以讓水凝結成液態。

The very first primitive ocean covered this young Earth and turned it into a water world.

最早的原始海洋覆蓋了這個年輕的地球，把它變成了一個水世界。

H2O is an essential ingredient for creating living things.

水是創造生物的基本要素。

So with all that water, life appeared on Earth about 3.7 billion years ago.

是以，有了這些水，生命在大約 37 億年前出現在地球上。

These earliest forms of life were microscopic organisms.

這些最早的生命形式是微觀生物。

But it was nearly a billion years after that that some of these organisms changed the course of the world.

但在那之後近 10 億年，其中一些生物改變了世界的進程。

Earth didn't stay as a water world very long.

地球作為水世界的時間並不長。

Soon, the very first continents emerged from the ancient ocean.

很快，第一塊大陸從遠古的海洋中浮現出來。

Scientists call them cratons.

科學家稱其為板岩。

As more and more land rose from the ocean, the very first supercontinent appeared on the planet.

隨著越來越多的陸地從海洋中升起，地球上出現了第一個超級大陸。

Valbara wasn't exactly a supercontinent.

瓦爾巴拉並不是一個超級大陸。

It was pretty small.

它非常小。

Scientists think it was smaller than the continent of Australia.

科學家認為，它比澳洲大陸還要小。

Around 2.4 billion years ago, cyanobacteria evolved to become our planet's first photosynthesizers.

大約 24 億年前，藍藻進化成為地球上最早的光合作用生物。

Finally, we had some oxygen producers to make Earth's atmosphere much more hospitable.

最後，我們有了一些製氧機，使地球的大氣層變得更加宜人。

And the rest is history, folks.

剩下的就是歷史了，夥計們。

Just kidding.

開個玩笑

We've still got a long way to go.

我們還有很長的路要走。

With all this new oxygen,

有了這些新氧氣

Earth's atmosphere had much lower levels of carbon dioxide.

地球大氣中的二氧化碳含量要低得多。

And that made the planet icy cold.

這讓地球變得冰冷。

Much of our young world froze over as Earth saw its first ice age.

隨著地球進入第一個冰河時期，我們年輕世界的大部分地區都結冰了。

Now, as Earth's atmosphere was changing, the continents were moving too.

現在，隨著地球大氣層的變化，大陸也在移動。

They broke up and reassembled into the next supercontinent,

它們解體後又重新組合成下一個超大陸、

Rodinia.

羅迪尼亞

Rodinia was a real supercontinent.

羅迪尼亞是一塊真正的超級大陸。

It may have been the largest supercontinent to ever cover the planet.

它可能是地球上最大的超級大陸。

And life?

生活呢？

Well, life finally became more complex.

好吧，生活終於變得複雜了。

But then something happened.

但後來發生了一件事。

Rodinia broke apart and a new supercontinent assembled.

羅迪尼亞斷裂，新的超大陸形成。

This one was called Pannotia.

這個人叫潘諾提亞。

Then, between about 540 and 485 million years ago, there was an explosion of new life.

然後，在大約 5.4 億年前到 4.85 億年前，新生命爆發了。

This time was called the Cambrian Explosion.

這一次被稱為寒武紀大爆發。

And the animals that evolved during this period had hard body parts, like shells or spines.

這一時期進化出的動物擁有堅硬的身體部位，比如貝殼或脊柱。

The most famous of all were the alien-looking trilobites.

其中最有名的是外形酷似外星人的三葉蟲。

Around 440 million years ago, the climate suddenly shifted, and the temperature of the ocean changed dramatically.

大約 4.4 億年前，氣候突然發生變化，海洋的溫度也急劇下降。

Earth saw its first mass extinction event.

地球發生了第一次大滅絕事件。

This was the Ordovician-Silurian extinction.

這就是奧陶紀-志留紀大滅絕。

And a majority of the life that had been spreading around the planet vanished.

在地球上蔓延的大部分生命都消失了。

Many of these life forms laid the foundation for the ecosystems that we have on Earth today.

其中許多生命形式為我們今天在地球上擁有的生態系統奠定了基礎。

Somewhere between 420 to 350 million years ago, the first trees arose from Earth's soil.

大約在 4.2 億到 3.5 億年前，地球的土壤中出現了第一批樹木。

And the first animals made their way to land too.

第一批動物也登上了陸地。

250 million years ago, the planet was covered by our last vast supercontinent, Pangea.

2.5 億年前，地球被我們最後一塊巨大的超級大陸--潘吉亞大陸所覆蓋。

Sadly, it was also during this period that Earth witnessed the greatest mass extinction event in our history, the Great Dying.

可悲的是，也正是在這一時期，地球發生了人類歷史上最嚴重的大滅絕事件--大滅絕。

Huge amounts of greenhouse gases and accelerated global warming wiped out about 90% of all species on Earth.

大量溫室氣體和加速的全球變暖消滅了地球上大約 90% 的物種。

But this mass extinction helped pave the way for the next wave of animals to evolve.

但這次大滅絕為下一波動物進化鋪平了道路。

240 to 230 million years ago, the first dinosaurs appeared.

2.4 億至 2.3 億年前，第一批恐龍出現了。

For the next 150 million years, they'd rule the land.

在接下來的 1.5 億年裡，它們將統治這片土地。

If you were there, you'd have witnessed the gigantic sauropod Argentinosaurus, the largest land animal ever.

如果你在那裡，你一定會親眼目睹有史以來最大的陸地動物--巨大的劍龍。

Or you might have been chased by one of the Earth's greatest apex predators, the T. rex.

或者，你可能被地球上最偉大的頂級掠食者之一霸王龍追趕過。

And you'd also witness Pangea breaking up and forming the continents we know today.

你還會目睹泛大陸解體，形成我們今天所知的大陸。

You may already know where this is headed.

您可能已經知道這將是什麼結果了。

66 million years ago, an asteroid slammed into our planet, right where Mexico sits now.

6600 萬年前，一顆小行星撞上了我們的星球，就在墨西哥現在所處的位置。

And it coughed up so much debris into the atmosphere that it blocked out the Sun.

它向大氣層噴出大量碎片，遮住了太陽。

This led to devastating climate changes that caused the dinosaurs to die out.

這導致了毀滅性的氣候變化，導致恐龍滅絕。

In the next wave of emerging animals, mammals became more common.

在下一波出現的動物中，哺乳動物變得更加常見。

Around 6 million years ago, the earliest known humans started walking this world.

大約 600 萬年前，已知最早的人類開始在這個世界上行走。

This species was called Sahelanthropus, though they still likely walked on all fours.

這個物種被稱為薩赫勒人，儘管他們仍然可能四肢著地。

4 million years ago, early humans began to walk upright.

400 萬年前，早期人類開始直立行走。

And about 1 million years later, they developed the first known tools, which they used to break things.

大約 100 萬年後，他們發明了第一批已知的工具，用來打碎東西。

Some 800,000 years ago, things sparked.

大約 80 萬年前，事情發生了變化。

These early humans discovered how to control fire, and could now cook food and provide themselves with heat.

這些早期人類發現瞭如何控制火，現在可以烹飪食物併為自己提供熱量。

Their brains continued to evolve, now more rapidly than ever.

他們的大腦繼續進化，現在比以往任何時候都更加迅速。

These humans learned to interact with each other and the surrounding world in whole new ways.

這些人類學會了以全新的方式與他人和周圍的世界互動。

Then, between 40,000 to 15,000 years ago, all other human species, besides Homo sapiens, went extinct.

然後，在距今 4 萬年到 1.5 萬年之間，除了智人之外，所有其他人類物種都滅絕了。

10,000 years ago,

一萬年前

Earth saw its earliest farmers.

地球上出現了最早的農民。

These previously nomadic humans stopped wandering the planet and finally put down their roots.

這些原本遊牧的人類停止了在地球上的流浪，終於紮下了根。

Jumping way forward to about 250 years ago, the Industrial Revolution took place.

時間回到大約 250 年前，工業革命爆發了。

We went through major technological, socioeconomic, and cultural transformations.

我們經歷了重大的技術、社會經濟和文化變革。

Rural-based farm societies became more industrialized urban ones.

以農村為基礎的農業社會變成了工業化程度更高的城市社會。

Our human population continued to grow.

我們的人口繼續增長。

By 1804, we reached 1 billion.

到 1804 年，我們的人口達到了 10 億。

By 1927, we'd hit 2 billion.

到 1927 年，我們已經達到了 20 億人。

And since the 1960s, the global population has risen faster and faster to where it is now, at over 8 billion people.

自 20 世紀 60 年代以來，全球人口增長越來越快，目前已超過 80 億。

And now, there's a new threat to human existence and many other forms of life here on Earth.

現在，人類的生存和地球上許多其他形式的生命都面臨著新的威脅。

Climate change.

氣候變化。

Temperatures and sea levels are rising worldwide, and biodiversity is declining.

全世界的氣溫和海平面都在上升，生物多樣性在減少。

We could be on the verge of another mass extinction event if things don't change.

如果不改變現狀，我們可能會面臨另一次大滅絕事件。

But that's a story for another WHAT IF.

不過，那是另一個 "如果 "的故事了。