The continents are moving. When will they collide? - Jean-Baptiste P. Koehl

譯者: Lilian Chiu 審譯者: Helen Chang

In the early 20th century,

在二十世紀初，

a meteorologist named Alfred Wegener noticed striking similarities

氣象學家艾爾佛雷德‧韋格納

注意到非洲和南美洲海岸 有非常顯著的相似之處。

between the coasts of Africa and South America.

These observations led him to propose a controversial new theory:

這些觀察讓他提出了 一個很爭議的新理論：

perhaps these and many other continents had once been connected

也許這些大陸和其他大陸

在過去曾經相連結， 是單一片巨型的大陸地。

in a single, gigantic landmass.

Wegener’s Theory of Continental Drift directly contradicted the popular opinion

韋格納的大陸漂移學說

和大眾的見解直接抵觸，

that Earth’s continents had remained steady for millennia,

一般認為地球上的大陸 數千年來都維持不變。

and it took almost 50 years for his advocates

他的擁護者花了近五十年的時間

to convince the larger scientific community.

才說服了更大的科學界。

But today, we know something even more exciting—

但現今，我們還知道更勁爆的——

Pangea was only the latest in a long lineage of supercontinents,

盤古大陸其實只是一系列 超大陸中最近的一個而已，

and it won’t be the last.

且它不會是最後一個。

Continental Drift laid the foundation for our modern theory of plate tectonics,

大陸漂移學說為我們現代的 板塊構造學說奠定了基礎，

which states that Earth’s crust is made of vast, jagged plates

該學說認為，地球的地殼是由 巨大、鋸齒狀的板塊構成，

that shift over a layer of partially molten rock called the mantle.

接著在岩石熔化 形成的地函層上移動。

These plates only move at rates of around 2.5 to 10 centimeters per year,

這些板塊移動的速度大約只有

每年二點五到十公分。

but those incremental movements shape the planet's surface.

但這些漸漸的移動， 形塑了地球的表面。

So to determine when a new supercontinent will emerge,

所以，若要判定新的 超大陸何時會出現，

we need to predict where these plates are headed.

我們就得預測這些板塊要朝哪裡去。

One approach here is to look at how they’ve moved in the past.

方式之一是參考它們過去的移動。

Geologists can trace the position of continents over time

地質學家可以追蹤大陸 在不同時間的位置，

by measuring changes in Earth’s magnetic field.

做法是測量地球磁場的改變。

When molten rock cools, its magnetic minerals are “frozen”

當熔化的岩石冷卻時，

它的磁性礦物會在 特定的時間點「凍結」。

at a specific point in time.

So by calculating the direction and intensity

所以，給定一塊岩石， 計算它的磁場方向和強度，

of a given rock’s magnetic field,

we can discover the latitude at which it was located at the time of cooling.

我們就能得知在冷卻時 它的位置緯度。

But this approach has serious limitations.

但這個方法有很大的限制。

For one thing, a rock’s magnetic field doesn’t tell us the plate’s longitude,

其一是岩石的磁場無法 告訴我們板塊的經度，

and the latitude measurement could be either north or south.

而測量出的緯度 則有可能是北緯或南緯。

Worse still, this magnetic data gets erased when the rock is reheated,

更糟的是，當岩石被重新加溫， 磁場資料就會被抹除，

like during continental collisions or volcanic activity.

比如在大陸碰撞 或火山活動時就會發生。

So geologists need to employ other methods to reconstruct the continents’ positions.

所以，地質學家需要採用其他方法

來重建大陸的位置。

Dating local fossils and comparing them to the global fossil record

對當地的化石做定年， 再和全球的化石記錄比對，

can help identifying previously connected regions.

能協助找出以前曾經 連結在一起的區域。

The same is true of cracks and other deformations in the Earth's crust,

裂隙以及地殼的其他變形亦是如此，

which can sometimes be traced across plates.

有時也可以跨板塊追蹤這些變形。

Using these tools, scientists have pieced together

運用這些工具，科學家已經拼湊出了

a relatively reliable history of plate movements,

相對算可靠的板塊漂移史，

and their research revealed a pattern spanning hundreds of millions of years.

他們的研究找出了 跨越數億年的模式。

What’s now known as the Wilson Cycle

現在我們所知的威爾遜循環

predicts how continents diverge and reassemble.

能預測大陸如何分離和重組。

And it currently predicts the next supercontinent will form

對於下一個超大陸何時 會形成，它目前的預測是

50 to 250 million years from now.

從現在算起的五千萬年 到兩億五千萬年之後。

We don’t have much certainty on what that landmass will look like.

我們不太能確定那一大片 陸地會是什麼樣子。

It could be a new Pangea that emerges from the closing of the Atlantic.

有可能是大西洋閉合起來， 形成新的盤古大陸。

Or it might result from the formation of a new Pan-Asian ocean.

也有可能是新的泛亞洲海洋 形成而導致的結果。

But while its shape and size remain a mystery,

但，雖然它的形狀和大小仍然成謎，

we do know these changes will impact much more than our national borders.

我們能肯定的是， 這些改變帶來的衝擊

會遠超過我們的國界。

In the past, colliding plates have caused major environmental upheavals.

在過去，板塊碰撞造成了 重大的環境劇變。

When the Rodinia supercontinent broke up circa 750 million years ago,

七億五千萬年前， 當羅迪尼亞超大陸瓦解時，

it left large landmasses vulnerable to weathering.

留下的大片陸地很難對抗日曬雨淋。

This newly exposed rock absorbed more carbon dioxide from rainfall,

這些新暴露出來的岩石會吸收 更多降雨中的二氧化碳，

eventually removing so much atmospheric CO2

最終，除去大氣中大量的二氧化碳，

that the planet was plunged into a period called Snowball Earth.

讓地球陷入了叫做雪球地球的時期，

Over time, volcanic activity released enough CO2 to melt this ice,

隨時間，火山活動釋放了 足夠讓冰融化的二氧化碳，

but that process took another 4 to 6 million years.

但這個過程又花了 四百萬到六百萬年。

Meanwhile, when the next supercontinent assembles,

而當下一塊超大陸組合成時，

it's more likely to heat things up.

比較有可能會造成升溫。

Shifting plates and continental collisions could create and enlarge

板塊移動以及大陸碰撞

會形成和擴大地殼的裂隙，

cracks in the Earth’s crust,

potentially releasing huge amounts of carbon and methane into the atmosphere.

很可能會釋放大量的 碳和甲烷到大氣中。

This influx of greenhouse gases would rapidly heat the planet,

溫室氣體的湧入會讓地球快速升溫，

possibly triggering a mass extinction.

有可能會引起物種滅絕。

The sheer scale of these cracks would make them almost impossible to plug,

這些裂隙的規模大到 幾乎不可能把它們塞住，

and even if we could, the resulting pressure would just create new ruptures.

就算塞住了，造成的壓力 也會形成新的破裂。

Fortunately, we have at least 50 million years to come up with a solution here,

幸運的是，我們還有至少 五千萬年可以找出解決方案，

and we might already be onto something.

且我們可能已經有所進展了。

In Iceland, recently conducted trials were able to store carbon in basalt,

近期在冰島進行的試驗

能夠將碳儲存在玄武岩中，

rapidly transforming these gases into stone.

快速將這些氣體轉變為石頭。

So it’s possible a global network of pipes

所以，有可能透過全球的管線網路

could redirect vented gases into basalt outcrops,

將排放出來的氣體重新導入 露出地面的玄武岩，

mitigating some of our emissions now and protecting our supercontinental future.

減緩一些我們現在的排放，

保護我們的超大陸未來。