Can clouds buy us more time to solve climate change? | Kate Marvel

譯者: Lilian Chiu 審譯者: Helen Chang

I am a climate scientist,

我是氣候科學家，

and I hate weather.

而我討厭天氣。

I have spent too much time in California,

我花了太多時間在加州，

and I strongly feel that weather should be optional.

我強烈認為， 天氣應該要是可選擇的。

(Laughter)

（笑聲）

So I don't want to experience clouds,

我並不想要體驗雲朵，

let alone study them.

更不用說研究它們了。

But clouds seem to follow me wherever I go.

但不論我到哪裡去， 雲朵似乎都跟著我。

The thing is, clouds are a real challenge for climate science.

重點是，對於氣候科學而言， 雲朵是非常有挑戰性的。

We don't know how they're going to react as the planet heats up,

我們不知道當地球溫度上升時， 它們會如何反應，

and hidden in that uncertainty

而隱藏在那不確定性中的，

might be hope.

可能是希望。

Maybe, just maybe,

可能，只是可能，

clouds could slow down global warming,

雲朵可能可以減緩全球暖化，

and buy us a little bit more time to get our act together,

幫我們爭取一些時間來努力想辦法，

which would be very convenient right now.

對現在會是非常好用的。

I mean, even I could put up with a few more cloudy days

我的意思是，即使是我 也願忍受多幾個陰天，

if clouds saved the planet.

如果雲朵能拯救地球的話。

Now, we are sure about some things.

我們能確定的有幾件事。

Carbon dioxide is a greenhouse gas,

二氧化碳是溫室氣體，

we're emitting a lot of it,

我們排放了很多二氧化碳，

and the planet is heating up.

且地球溫度在上升。

Case closed.

結案。

But I still go to work every day.

但我仍然每天都要工作。

It turns out that there is a lot that we don't understand

結果發現，

關於氣候改變，還有著很多 我們不了解的地方。

about climate change.

In particular, we haven't answered

特別是，我們尚未回答

what seems to be a very fundamental question.

一個似乎非常基礎的問題。

We know it's going to get hot,

我們知道會越來越熱，

but we don't know exactly how hot it's going to get.

但我們不知道究竟會到多熱。

Now, this is a really easy question to answer

這是個很容易回答的問題，

if one of you would like to give me a time machine.

只要有人能給我一台時光機器。

But I'm going to be honest with you:

但我得對各位說實話：

if I had a time machine,

如果我有一台時光機器，

I would not be hanging out at this particular point in history.

我不會在歷史上的這個時間點逗留。

So in order to see the future,

所以，為了看到未來，

we have to rely on the output of computer simulations --

我們要仰賴電腦模擬的輸出結果──

climate models, like this one.

氣候模型，就像這一個。

Now, in my line of work,

在我的這個行業，

I encounter many very charming people on the internet

我會在網上遇到許多非常迷人的人，

who like to tell me that climate models are all wrong.

他們會告訴我氣候模型都是錯的。

And I would just like to say:

我只想要說：

no kidding!

別開玩笑了！

Seriously? I get paid to complain about climate models.

當真嗎？我領薪水來抱怨氣候模型。

But we don't want models to be perfect.

但我們不要求模型完美，

We want them to be useful.

只要有用就好。

I mean, think about it:

想想看：

a computer simulation

能夠完全重製所有現實的電腦模擬。

that's able to exactly reproduce all of reality.

That's not a climate model;

那不是氣候模型；

That's "The Matrix."

那是《駭客任務》。 （譯註：電影名稱）

So, models are not crystal balls.

所以，模型不是水晶球。

They're research tools,

它們是研究工具，

and the ways in which they're wrong can actually teach us a lot.

它們錯誤的方式 其實能教我們很多東西。

For example:

比如：

different climate models are largely able to capture

不同的氣候模型能捕捉到大部份

the warming that we've seen so far.

我們目前所看到的暖化現象。

But fast-forward to the end of the century

但快轉到這個世紀末，

under a business-as-usual scenario,

在一切照常的情況下，

and climate models don't really agree anymore.

氣候模型就不再一致了。

Yeah, they're all warming; that's just basic physics.

是的，它們都變暖， 那只是基本的物理。

But some of them project catastrophe --

但有些模型預測會有大災難──

more than five times the warming we've seen already.

暖化的程度是我們 目前已看到的五倍以上；

And others are literally more chill.

其他模型則預測稍微涼一些。

So why don't climate models agree on how warm it's going to get?

所以，為什麼氣候模型對於 將來有多暖的預測會不一致呢？

Well, to a large extent,

有很大的程度，

it's because they don't agree on what clouds will do in the future.

是因為它們對於雲朵在未來 扮演什麼角色的看法不一致。

And that is because, just like me,

那是因為，就跟我一樣，

computers hate clouds.

電腦也討厭雲朵。

Computers hate clouds because they're simultaneously very large

電腦討厭雲朵

是因為它們同時可大可小。

and very small.

Clouds are formed

雲朵的形成，

when microscopic water droplets or ice crystals coalesce

是顯微鏡才看得到的小水滴或冰晶體

包圍在小粒子的周圍結合。

around tiny particles.

But at the same time, they cover two-thirds of the earth's surface.

但同時，它們覆蓋了 三分之二的地球表面。

In order to really accurately model clouds,

為了要真正精確地建立雲朵的模型，

we'd need to track the behavior of every water droplet and dust grain

我們必須要追蹤整個大氣當中

每個水滴與塵粒的行為，

in the entire atmosphere,

and there's no computer powerful enough to do that.

沒有電腦強大到可以做到這一點。

So instead, we have to make a trade-off:

因此，我們得要做取捨：

we can zoom in and get the details right,

我們可以放大一小塊範圍， 以求細節的正確，

but have no idea what's going on worldwide;

但就不知道全世界發生什麼事；

or, we could sacrifice realism at small scales

或者，我們可以犧牲 小規模的真實性，

in order to see the bigger picture.

以求看到更大更整體的狀況。

Now, there's no one right answer,

沒有正確的答案，

no perfect way to do this,

沒有完美的方式，

and different climate models make different choices.

不同的氣候模型會做不同的選擇。

Now, it is unfortunate

很不幸的是，

that computers struggle with clouds,

電腦很難處理雲朵，

because clouds are crucially important

因為雲朵在調節地球溫度上，

in regulating the temperature of the planet.

扮演非常重要的角色。

In fact, if all the clouds went away,

事實上，如果所有的雲朵都沒了，

we would experience profound climate changes.

我們會經歷到很劇烈的氣候改變。

But without clouds,

但若沒有雲朵，

would it be warmer or colder?

會比較溫暖或比較寒冷？

The answer is both.

答案是，都會。

So I'm going to be honest with you, I am not a cloud spotter.

老實告訴各位，我不是賞雲者。

My favorite type of cloud is none.

我最喜歡晴朗無雲。

But even I know that clouds come in all shapes and sizes.

但即使是我這種人， 也知道雲朵有各種形狀大小。

Low, thick clouds like these are really good at blocking out the sun

像這樣的低厚雲層很能夠阻擋陽光，

and ruining your barbecue,

讓你的烤肉活動泡湯；

and high, wispy clouds like these cirrus

而像這些卷雲的高雲，

largely let that sunlight stream through.

會讓大部份的陽光穿過。

Every sunny day is the same,

晴天全都一樣，

but every cloudy day is cloudy in its own way.

但每個陰天有它自己的多雲方式。

And it's this diversity

正是這種多樣性，

that can make the global impact of clouds very hard to understand.

讓雲朵的全球性影響變得難以了解。

So to see this global effect of clouds,

要了解雲朵的全球性效應，

it really helps to take a selfie.

拍張自拍照是很有幫助的。

It will never cease to blow my mind

我們能夠從外太空來看我們的星球， 這點總是讓我感到不可思議，

that we can see our planet from outer space,

but we can't see all of it.

但我們無法看到它的全部。

Clouds are blocking the view.

雲朵會阻擋視線。

That's what they do.

這是它們的功能之一。

These low, thick clouds are extremely effective sunshades.

低空的厚雲層是非常有效的遮陽板。

They turn back about 20 percent of everything the sun sends us.

雲朵反射回去 20% 的陽光，

That is a lot of wasted solar power.

浪費掉許多的太陽能。

So, low clouds are powerful sunshades,

所以，低雲是很強大的遮陽板，

making the planet cooler.

讓地球比較涼快。

But that's not the only effect of clouds.

但雲朵的效應不只如此。

Our planet has a temperature,

我們的星球有熱度，

and like anything with a temperature,

就像所有有熱度的東西一樣，

it's giving off heat.

它會散熱。

We are radiating thermal energy away into space,

我們向太空輻射熱能。

and we can see this in the infrared.

這現象用紅外線就可以看到。

Once again, clouds are blocking the view.

同樣的，雲朵會阻擋視線。

That's because high clouds live in the upper reaches of the atmosphere,

那是因為高雲位在大氣的上層，

where it's very cold.

那裡非常寒冷。

And this means that they lose very little heat to space themselves.

這意味著它們本身 散失到太空的熱能很少。

But at the same time, they block the heat coming up from the planet below.

但同時，它們阻擋了 下方的地球向上散熱。

The earth is trying to cool itself off,

地球試著冷卻自己，

and high clouds are getting in the way.

而高雲卻從中作梗。

The result is a very powerful greenhouse effect.

結果就是非常強大的溫室效應。

So, clouds play this very large and dual role

所以，雲朵在氣候系統中

扮演著非常大的雙重角色。

in the climate system.

We've got low clouds that act like a sunshade,

我們有低雲當遮陽板，

cooling the planet,

冷卻地球，

and high clouds which act like a greenhouse,

也有高雲當溫室，

warming the planet.

暖化地球。

Right now, these two effects -- they don't cancel out.

現今，這兩種效應並不會互相抵消。

That sunshade -- it's a little bit more powerful.

遮陽的力量稍大一些些。

So if we got rid of all the clouds tomorrow,

所以，如果我們明天 就清除所有的雲朵──

which, for the record, I am not advocating,

聲明一下，我沒在提倡這件事喔──

our planet would get warmer.

那麼地球就會暖化。

So clearly, all of the clouds are not going away.

所以很顯然，雲不會消失。

But climate change is change.

但氣候改變就是改變。

So we can ask:

所以我們可以問：

How will global warming change clouds?

全球暖化會如何改變雲朵？

But remember, clouds are so important

但切記雲朵

在調節地球溫度的重要角色，

in regulating the earth's temperature,

and they both warm and cool the planet.

它們會冷卻也會暖化地球。

So even small changes to cloud cover

所以即使雲朵的覆蓋稍微變了，

could have profound consequences.

也可能會造成深切的影響。

So we might also ask:

所以我們也可以問：

How will clouds change global warming?

雲朵會如何改變全球暖化？

And that is where there might be space for hope.

那可能是能找到希望的地方。

If global warming triggers cloud changes

如果全球暖化觸發了雲朵的改變，

that make for a less powerful greenhouse or a more effective sunshade,

導致溫室變弱、 或遮陽板變得更有效，

then that would enhance the cooling power of clouds.

那麼那就會強化雲朵的冷卻力。

It would act in opposition to global warming,

它的功能就會和全球暖化正好相反，

and that's what's happening in those climate models

那就是那些預測暖化將會緩和的

that project relatively muted warming.

氣候模型中所發生的現象。

But climate models struggle with clouds,

但，氣候模型很難處理雲朵，

and this uncertainty -- it goes both ways.

而這不確定性是雙向的。

Clouds could help us out with global warming.

雲朵能協助我們處理全球暖化，

They could also make it worse.

也可能讓它惡化。

Now, we know that climate change is happening

現在，我們知道氣候改變正在發生，

because we can see it:

因為我們看見：

rising temperatures, melting icecaps, shifts in rainfall patterns.

氣溫上升、冰山溶化、 降雨模式轉變。

And you might think that we could also see it in the clouds.

你可能會認為，我們也能 在雲朵上看到改變。

But here's something else unfortunate:

但還有件不幸的事：

clouds are really hard to see.

雲朵真的很難看見。

I see everybody from the Pacific Northwest

我看見來自太平洋西北地區的每個人

is like, "I have some suggestions for you."

都像在說：「我想給你些建議。」

(Laughter)

（笑聲）

And you guys, we have tried looking up.

各位，我們有試過抬頭向上看了。

(Laughter)

（笑聲）

But in order to do climate science,

但為了要做氣候科學，

we need to see all of the clouds, everywhere, for a very long time.

我們得要看見各處的所有雲朵， 且持續很長一段時間。

And that's what makes it hard.

那就是困難之處。

Now, nothing sees more clouds than a satellite --

現在，能看見最多雲朵的就是衞星，

not even a British person.

連英國人都看不到那麼多。

(Laughter)

（笑聲）

And fortunately, we do have satellite observations of clouds

幸運的是，我們的確有 衛星觀測雲朵的資料，

that, like me, date back to the 1980s.

就像我，可追溯到 1980 年代。

But these satellites were designed for weather,

但這些衛星是為了天氣設計的，

not climate.

不是氣候。

They weren't in it for the long haul.

它們無法持久。

So to get that long-term trend information,

若要取得長期趨勢的資訊，

we need to do climate science.

我們必須要做氣候科學。

We have to stitch together the output of multiple satellites

我們得把不同視角、運行軌道，

with different viewing angles and orbits

帶著不同照相設備的多個衛星

and carrying different camera equipment.

所輸出的資料結合起來。

And as a result,

而結果和我們的知識有差距。

there are gaps in our knowledge.

But even from this very cloudy picture,

但即使是從這像多雲一樣 非常朦朧的狀況中，

we're starting to get hints of a possible future.

我們也開始得到些關於 可能發生之未來的暗示。

When we looked at the observations,

當我們看這些觀測資料時，

one thing jumped out at us:

有一點引起了我們的注意：

the clouds are moving.

雲朵在移動。

As the planet's temperature increases,

隨著地球溫度上升，

high clouds rise up.

高雲會上升。

They move to the colder upper reaches of the atmosphere,

它們移向大氣中更上層更冷的地方，

and this means that even as the planet heats up,

這意味著，即使地球在變暖，

high clouds don't.

高雲卻不會。

They remain at roughly the same temperature.

它們的溫度大致上維持相同。

So they are not losing more heat to space.

所以它們並沒有散失更多熱到太空。

But at the same time, they're trapping more heat

但同時卻圈住了更多

from the warming planet below.

在下方暖化中的地球的熱能。

This intensifies the greenhouse effect.

這會讓溫室效應加劇。

High clouds are making global warming worse.

高雲會讓全球暖化的情況更糟。

Clouds are moving in other dimensions, too.

雲朵也向其他維度移動。

The atmospheric circulation, that large-scale motion

大氣環流，

大氣中空氣和水的大規模移動

of air and water in the atmosphere,

is changing,

正在改變，

and clouds are going with it.

而雲朵也隨之移動。

On large scales,

大規模來看，

clouds seem to be moving from the tropics toward the poles.

雲朵似乎是從熱帶移向極地。

It's kind of like your grandparents in reverse.

這有點像是你的祖父母返老還童。

And this matters,

這有其重要性，

because if your job is to block incoming sunlight,

因為如果你要阻擋太陽光射進來，

you are going to be much more effective in the tropics

你身在熱帶會有效許多，

under that intense tropical sun

熱帶的太陽非常強烈，

than you are in higher latitudes.

在較高的緯度就比較沒效。

So if this keeps up,

所以如果繼續這樣下去，

this will also make global warming worse.

這也會讓全球暖化再惡化。

And what we have not found,

儘管花了數年在尋找，

despite years of looking,

我們仍然尚未發現

is any indication of the opposite.

任何顯示相反情況的徵兆。

There is no observational evidence

觀察到的證據未能證明

that clouds will substantially slow down global warming.

雲朵在本質上能減緩全球暖化。

The earth is not going to break its own fever.

地球並不會治好它自己的發燒。

Now, there are still uncertainties here.

這裡仍然有著不確定性。

We don't know for sure

我們不能確定

what the future holds.

未來會怎樣。

But we are sending our kids there,

但我們的孩子正朝向未來的不歸路。

and they are never coming back.

I want them to be prepared for what they'll face,

我警告他們，對將要 面臨的狀況要有心理準備，

and that is why it is so important

因此，非常重要的事就是要讓那些

to keep our earth-observing satellites up there

觀察地球的衛星能繼續在天上運行，

and to hire diverse and smart and talented people

並要僱用多樣化、聰明有才華的人，

who do not hate clouds

不討厭雲朵的人，

to improve the climate models.

來改善氣候模型。

But uncertainty is not ignorance.

但不確定性並不等同無知。

We don't know everything,

我們並非全知，

but we don't know nothing,

但也不是全然無知，

and we know what carbon dioxide does.

且我們知道二氧化碳的影響。

I started my career as an astrophysicist,

我最初的職業是天體物理學家，

so you can believe me

所以你們可以相信我，

when I say that this is the greatest place in the universe.

我說這裡是宇宙中最棒的地方。

Other planets might have liquid water.

其他的星球可能有液態水。

On earth, we have whiskey.

在地球，我們有威士忌。

(Laughter)

（笑聲）

(Applause)

（掌聲）

We are so lucky to live here,

我們如此有幸能住在這裡，

but let's not push our luck.

但不要得寸進尺以為好運會長久。

I don't think that clouds will save the planet.

我不認為雲朵能拯救地球。

I think that's probably up to us.

拯救地球的責任可能要由我們承擔。

Thank you.

謝謝。

(Applause)

（掌聲）