It's the story of carbon.

碳循環。

And over billions of years, it has evolved to look something like this.

經過數十億年的演化後，碳循環今天是這麼進行的。

It starts with a plant.

它從一株植物開始。

Plants and microorganisms absorb carbon dioxide from the atmosphere.

植物與微生物從大氣層中吸收二氧化碳。

Then they use energy from the sun to convert that carbon into oxygen and sugar, which they use to grow.

接著用來自太陽的能量把二氧化碳轉化成氧氣，以及用以生長的糖分。

And as they grow, they emit some carbon back into the atmosphere.

植物與微生物一邊生長，一邊把部分的碳釋放回大氣層。

But all plants eventually die.

然而每一株植物最終都會死亡。

And some are consumed by bacteria, others by larger beasts.

有些被細菌分解，有些則是被大型野獸吃掉。

These animals eat plants for energy.

這些動物食用植物是為了獲取能量。

And they breathe out carbon.

動物也會藉呼吸釋出碳。

But eventually, those animals die, too.

而最終動物也會死亡。

And they end up in the ground.

被埋進土裡。

Meanwhile, a similar thing happens in the ocean.

與此同時，海洋中也有類似的事情發生。

Coral and plankton need carbon from the water to survive.

珊瑚與浮游生物需要水中的碳才能生存。

Luckily, the ocean has carbon because it absorbs some from the atmosphere.

幸運的是，海洋存有吸取自大氣層的碳。

And, when rain falls to the earth, it grabs some carbon from the atmosphere and from rocks.

當雨水落至地表，也會順道夾帶一些來自大氣層與岩石的碳。

And flows into the ocean, where the coral and plankton use carbon to grow.

接著流進海水，讓珊瑚和浮游生物得到碳以生長。

Or other animals use it to grow.

或者其他海洋動物的生長也需要碳。

But just like animals, the coral and plankton die, too.

不過就和動物一樣，珊瑚和浮游生物也會死亡。

In short, all living things are made of carbon, and they eventually end up in the ground.

簡單來說，所有生物都由碳所構成，且最終都會被埋進土裡。

Some of that carbon will eventually get back to the atmosphere.

其中有些碳最終會回到大氣層。

But some of it normally stays in the ground.

也有一部分通常會留在土裡。

Usually, dead things decay and turn into rocks.

大致上來說死亡的生物會腐壞、變成石頭。

Eventually, they're crushed, and extreme heat and pressure causes them to melt and emit the carbon, which is trapped underground.

而石頭最後會被壓碎，極端的高溫高壓使石頭融化、釋放出碳，這些碳被關在地底下。

Over time, that trapped carbon eventually escapes into the atmosphere when volcanoes erupt.

隨著時間過去，困住的碳終究會因為火山爆發而被釋放到大氣層。

And the cycle starts again.

然後整個循環又會重新開始。

But occasionally, dead plants and animals don't turn into rock.

但偶爾死亡的動植物不會變成石頭。

They don't decay fast enough, so they turn into oil, coal, or natural gas.

他們腐壞得不夠快，於是轉變成石油、煤，或是天然氣。

This carbon gets stuck in the ground.

此形式的碳會停留在地表。

This is the elegant system that keeps carbon cycling through Earth at a steady pace.

正是此一巧妙的系統，讓地球上的碳能以穩定的速度循環。

Carbon in the atmosphere keeps some heat from leaving Earth.

大氣層中的碳將部分熱能保留在地球上。

It keeps Earth at a stable temperature.

這讓地球維持穩定的溫度。

But very recently, one of these animals started to dig up the carbon in the ground.

可是就在最近，有一種動物開始把地表累積的碳挖出來。

They took the carbon that was stuck in the ground and put it back into the atmosphere.

他們把所在地底的碳取出並釋放回大氣層。

They did this so much, in such a short time span, that this cycle was disrupted.

他們在極短的時間內重複此舉，干擾了整個碳循環。

Too much carbon was being put into the atmosphere.

有太多碳被釋放回大氣層了。

Heat that would normally be able to escape bounced back and stayed on Earth.

原本應該流失的熱能現在被反彈回來，留在地球上。

And Earth started to get warmer and warmer.

於是地球開始變得越來越熱。

Really recently, just a few months ago, more than 100 bipedal scientists said they might only have 12 years to stop a disastrous amount of warming.

最近—大概才幾個月前—超過 100 名科學家表示他們大概只剩 12 年可以阻止災難性的暖化現象。

So these animals not only need to stop putting carbon in the atmosphere, but also get carbon out of the atmosphere.

所以這些動物 (人類) 不僅需要停止把碳釋放到大氣層中，也得想辦法把已經在大氣層中的碳去除。

They found that one way to remove carbon is to grow more plants.

人類想到一個辦法：種植更多植物來去除碳。

They could stop cutting down trees.

他們可以停止砍伐林木。

Or raise livestock in ways that help restore grass.

或者飼養能夠幫助恢復植被的牲畜。

Another way is to let plants suck up carbon from the atmosphere but then burn them for energy.

另一個辦法是先讓植物吸收大氣層中的碳，再燃燒植物獲取能源。

And then trapping the carbon they emit underground.

接著把植物釋放出的碳困在地底下。

They could also build machines to suck air from the atmosphere and filter out the carbon.

人類也可以打造一台機器，用來吸取大氣層中的氣體，接著把碳過濾掉。

But they haven't figured out how to do this fast enough.

可是人類還不清楚要怎麼做才來得及。

There are many ways these animals can tweak this cycle to suck carbon out of the atmosphere.

人類有許多方法可以修正碳循環，把大氣層中的碳吸走。

A combination of them is probably the best way forward.

綜合所有解方來行動或許是最明智的選擇。

But, first, these animals need to figure out how to stop putting it there in the first place.

然而首先，我們得先想想如何從一開始就不要有碳排放。