Should we create a solar shade to cool the earth? | Danny Hillis

譯者: Lilian Chiu 審譯者: SF Huang

[A provocation from Danny Hillis:]

【丹尼 • 希利斯的挑釁：】

[It's time to start talking about engineering our climate]

【是開始談處理氣候議題的時候了】

What if there was a way to build a thermostat

如果有辦法打造一個自動調溫器，

that allowed you to turn down the temperature of the earth

讓你可以隨時隨地

調降地球的溫度？

anytime you wanted?

Now, you would think if somebody had a plausible idea about how to do that,

若有人有可行的想法，

everybody would be very excited about it,

每個人應該都會感到非常興奮，

and there would be lots of research on how to do it.

而且會有很多相關的研究報告才對。

But in fact, a lot of people do understand how to do that.

事實上，許多人確實知道要如何做。

But there's not much support for research in this area.

但是，這個領域並沒有得到很多 相關研究的支持。

And I think part of it

我認為部分原因，

is because there are some real misunderstandings about it.

是大家對它存在著一些誤解。

So I'm not going to try to convince you today that this is a good idea.

今天，我不會試著說服 各位相信這是個好點子。

But I am going to try to get your curiosity going about it

但我會試著讓各位對它感到好奇，

and clear up some of the misunderstandings.

同時也澄清一些誤解。

So, the basic idea of solar geoengineering

太陽能地球工程的基本想法是，

is that we can cool things down

只要把稍微多一點的太陽光

just by reflecting a little bit more sunlight

反射回太空，

back into space.

我們就能將地球降溫。

And ideas about how to do this have been around literally for decades.

數十年來人們探究要如何實踐。

Clouds are a great way to do that, these low-lying clouds.

雲會是很棒的方法，這些低空的雲。

Everybody knows it's cooler under a cloud.

大家都知道，在雲底下比較涼爽。

I like this cloud because it has exactly the same water content

我喜歡這種雲，因為它的水含量

as the transparent air around it.

和周圍的透明空氣一樣。

And it just shows that even a little bit of a change in the flow of the air

這意味著即使空氣的流動 只有一丁點的改變，

can cause a cloud to form.

就能形成雲。

We make artificial clouds all the time.

我們一直都在製造人造雲。

These are contrails, which are artificial water clouds

這些是凝結尾，也就是人造水雲，

that are made by the passing of a jet engine.

是噴射機引擎在飛行時所產生的。

And so, we're already changing the clouds on earth.

我們已經在改變地球上的雲了。

By accident.

非特意的。

Or, if you like to believe it, by supersecret government conspiracy.

或是，也有人相信 是政府的超神秘陰謀。

(Laughter)

（笑聲）

But we are already doing this quite a lot.

但，我們已經常常在製造雲了。

This is a NASA picture of shipping lanes.

這是太空總署拍的海上航道照片。

Passing ships actually cause clouds to form,

航行的船隻會導致雲的形成，

and this is a big enough effect

這影響夠大，

that it actually helps reduce global warming already by about a degree.

實際上已經有助於 減輕全球暖化大約一度。

So we already are doing solar engineering.

所以我們已經在做太陽能工程了。

There's lots of ideas about how to do this.

要如何去實踐它的點子有很多。

People have looked at everything,

人們的想法應有盡有，

from building giant parasols out into space

從在外太空建造巨型陽傘，

to fizzing bubble waters in the ocean.

到使海水產生氣泡都有。

And some of these are actually very plausible ideas.

當中有一些想法似乎是蠻合理的。

One that was published recently by David Keith at Harvard

近期，哈佛的大衛 • 凱斯 在刊物中提出了一個想法，

is to take chalk and put dust up into the stratosphere,

把白堊（粉筆）的粉末 投放到同溫層當中，

where it reflects off sunlight.

它會把太陽光反射回去。

And that's a really neat idea,

那是很棒的想法，

because chalk is one of the most common minerals on earth,

因為白堊是地球上 最常見的礦物之一，

and it's very safe -- it's so safe, we put it into baby food.

且它非常安全──安全到 我們會把它放到嬰兒食物中。

And basically, if you throw chalk up into the stratosphere,

基本上，若你把白堊放到同溫層中，

it comes down in a couple of years all by itself, dissolved in rainwater.

幾年後它自己會落下， 在雨水中分解。

Now, before you start worrying about all this chalk in your rainwater,

在各位開始擔心雨水中的白堊之前，

let me explain to you how little of it it actually takes.

先讓我解釋需要使用的量有多麼少。

And that turns out to be very easy to calculate.

結果發現，這用量很容易計算。

This is a back-of-the-envelope calculation I made.

這是我在信封背後做的計算。

(Laughter)

（笑聲）

(Applause)

（掌聲）

I assure you, people have done much more careful calculations,

我向各位保證， 有人做過更精密的計算，

and it comes out with the same answer,

結果答案是相同的，

which is that you have to put chalk up at the rate of about 10 teragrams a year

答案是，你需要每年放上 大約一千萬公噸的白堊，

to undo the effects of the CO2 that we've already done --

來弭平二氧化碳已經造成的效應──

just in terms of temperature, not all the effects, but the temperature.

只有溫度上的效應， 不是所有的效應，僅限於溫度。

So what does that look like?

所以，那看起來是什麼樣子？

I can't visualize 10 teragrams per year.

我無法具像化 每年一千萬公噸的樣子。

So I asked the Cambridge Fire Department and Taylor Milsal

所以，我請劍橋消防局 和泰勒 • 米爾索

to lend me a hand.

來幫我一個忙。

This is a hose pumping water at 10 teragrams a year.

這水管灌注出的水量， 就是一年一千萬公噸。

And that is how much

只要把這麼多的量

you would have to pump into the stratosphere

灌注到同溫層，

to cool the earth back down to pre-industrial levels.

就能讓地球降溫到 工業時代以前的溫度。

And it's amazingly little; it's like one hose for the entire earth.

這份量少得驚人； 整個地球只要這一根水管。

Now of course, you wouldn't really use a hose,

當然，我們不會真的用水管，

you'd fly it up in airplanes or something like that.

可能會用飛機載上去之類的方式。

But it's so little, it would be like putting a handful of chalk

但，需要的量相當少， 就像是把一把白堊

into every Olympic swimming pool full of rain.

丟到裝滿雨水的每個奧運游泳池中。

It's almost nothing.

幾乎沒感覺。

So why don't people like this idea?

所以，為什麼大家不喜歡這個想法？

Why isn't it taken more seriously?

它為何沒被更認真看待？

And there are some very good reasons for that.

這背後有些很好的理由。

A lot of people really don't think we should be talking about this at all.

很多人完全不認為 我們應該要談這些。

And, in fact, I have some very good friends in the audience

事實上，在觀眾當中 有一些我非常要好的朋友，

who I respect a lot,

我很尊敬他們，

who really don't think I should be talking about this.

他們完全不認為我應該來談這個。

And the reason is that they're concerned

因為他們關心的是，

that if people imagine there's some easy way out,

如果大家知道會有簡單的解決方案，

that we won't give up our addiction to fossil fuels.

那麼我們就不會放棄 對化石燃料的依賴了。

And I do worry about that.

我確實也會擔心這點。

I think it's actually a serious problem.

我認為這其實是個嚴重的問題。

But there's also, I think, a deeper problem,

但，我認為還有一個更深入的問題，

which is: nobody likes the idea of messing with the entire earth --

那就是：沒有人會喜歡 去亂搞整個地球──

I certainly don't.

我肯定不喜歡。

I love this planet, I really do.

我愛這個星球，真的。

And I don't want to mess with it.

我不想亂搞它。

But we're already changing our atmosphere,

但我們已經在改變我們的大氣了，

we're already messing with it.

我們已經在亂搞它了。

And so I think it makes sense for us to look for ways

所以我認為這是合理的， 我們應該要找些方式

to mitigate that impact.

來把衝擊給減少。

And we need to do research to do that.

我們需要去做相關的研究。

We need to understand the science behind that.

我們需要了解它背後的科學。

I've noticed that there's a theme that's kind of developed at TED,

我注意到，在 TED 有個主題正在發展，

which is kind of, "fear versus hope,"

類似是「恐懼與希望」，

or "creativity versus caution."

或「創意與謹慎」。

And of course, we need both of those.

當然，我們兩者都需要。

So there aren't any silver bullets.

沒有任何簡單快速的解法。

This is certainly not a silver bullet.

這肯定不是簡單快速的解決方法。

But we need science to tell us what our options are;

但我們需要科學 來告訴我們有哪些選項，

that informs both our creativity and our caution.

那樣就能同時為我們的 創意和謹慎提供資訊。

So I am an optimist about our future selves,

所以對於我們的未來， 我抱持著樂觀的態度，

but I'm not an optimist because I think our problems are small.

但我樂觀的原因並不是 因為我們的問題很小。

I'm an optimist because I think our capacity to deal with our problems

我樂觀的原因是， 我認為我們處理問題的能力

is much greater than we imagine.

遠超過我們的想像。

Thank you very much.

非常謝謝。

(Applause)

（掌聲）

This talk sparked a lot of controversy at TED2017,

這場演說在 TED 2017 引發了許多爭論，

and we encourage you to look at discussions online

我們鼓勵大家上網看看討論，

to see other points of view.

了解不同的觀點。