David Keith: A surprising idea for "solving" climate change

譯者: Bob Lo 審譯者: Lin Su-Wei(林書暐)

You've all seen lots of articles on climate change,

各位已看過不少關於氣候變遷的文章，

and here's yet another New York Times article,

而這邊是另一篇紐約時報的相關報導。

just like every other darn one you've seen.

與其他各位看過的文章一樣，

It says all the same stuff as all the other ones you've seen.

這篇文章講的是千篇一律的東西，

It even has the same amount of headline as all the other ones you've seen.

甚至連篇幅也與其他文章大同小異。

What's unusual about this one, maybe, is that it's from 1953.

不過可能較不尋常的地方是，這篇文章寫於1953年。

And the reason I'm saying this

我會這麼說，

is that you may have the idea this problem is relatively recent.

是因為各位可能以為，氣候變遷是最近的問題。

That people have just sort of figured out about it, and now

各位會認為人類才剛體認到這個問題，

with Kyoto and the Governator and people beginning to actually do something,

而現在，如京都協定書及州長阿諾致力減少溫室氣體排放等等的努力，

we may be on the road to a solution.

我們其實已經開始著手解決這項問題。

The fact is -- uh-uh.

不過事實是，我們還差的遠呢。

We've known about this problem for 50 years, depending on how you count it.

早在50年前人們便已發現氣候變遷的問題。

We have talked about it endlessly over the last decade or so.

過去十年來也不斷針對這個問題進行討論，

And we've accomplished close to zip.

但對於解決問題實際上並無任何建樹。

This is the growth rate of CO2 in the atmosphere.

這張圖是大氣層中二氧化碳的增長率。

You've seen this in various forms,

各位已看過許多類似的圖表，

but maybe you haven't seen this one.

但或許還沒看過這張。

What this shows is that the rate of growth of our emissions is accelerating.

這張圖告訴我們，溫室氣體排放成長正不斷加速，

And that it's accelerating even faster

而其速度之快，

than what we thought was the worst case just a few years back.

甚至超過我們幾年前所預測的最壞情況。

So that red line there was something that a lot of skeptics said

這條紅線有許多人提出質疑，

the environmentalists only put in the projections

說是環保份子故意放在圖表中

to make the projections look as bad as possible,

好讓人們覺淂情況已經很糟。

that emissions would never grow as fast as that red line.

他們說溫室氣體排放的成長速度永遠不可能達到紅線的標準。

But in fact, they're growing faster.

但實際上，現在的成長速度已不止於此。

Here's some data from actually just 10 days ago,

這裡是大約十天前所測得的實際數據，

which shows this year's minimum of the Arctic Sea ice, and it's the lowest by far.

我們可以看到，今年北極海冰的最小面積為歷年來的新低點，

And the rate at which the Arctic Sea ice is going away is a lot quicker than models.

而北極海冰消融的速度還要比模型中顯示的更快。

So despite all sorts of experts like me flying around the planet and

所以，儘管像我這樣的各領域專家不斷搭機在世界各處奔波，

burning jet fuel, and politicians signing treaties --

同時各國也陸續簽訂各項協議，

in fact, you could argue the net effect of all this has been negative,

但實際上，你可能覺得這些努力對環保只有負面效益，

because it's just consumed a lot of jet fuel. (Laughter)

因為我們只是大量浪費飛機燃油而已。

No, no! In terms of what we really need to do to put the brakes on

不，不是這樣的! 如果說我們的目的是減緩這個根深蒂固的系統，

this very high inertial thing -- our big economy -- we've really hardly started.

也就是我們這個龐大的經濟體，我們根本還沒起步。

Really, we're doing this, basically. Really, not very much.

我們現在在做的其實就是像這樣，非常非常地有限。

I don't want to depress you too much.

我不想讓你們太失望，

The problem is absolutely soluble, and even soluble in a way that's reasonably cheap.

氣候變遷的問題絕對有解決之道，甚至相對來說還算低價，

Cheap meaning sort of the cost of the military, not the cost of medical care.

好比只需要提撥點軍事預算，而不用動到醫療相關的支出;

Cheap meaning a few percent of GDP.

好比只需要GDP的幾個百分點而已。

No, this is really important to have this sense of scale.

不，說真的，這樣的比例概念是十分重要的。

So the problem is soluble, and the way we should go about solving it is, say,

所以這個問題是可解決的，而現在主要的方式

dealing with electricity production,

便是處理發電問題

which causes something like 43-or-so percent and rising of CO2 emissions.

其約佔43%以上的二氧化碳排放，並持續增加中。

And we could do that by perfectly sensible things like conservation,

要做的事情其實觸手可及，如節約用電，

and wind power, nuclear power and coal to CO2 capture,

以及開發風力、核能、煤炭發電、甚至碳封存技術等。

which are all things that are ready for giant scale deployment, and work.

這些都是可大規模佈局及著手的選擇。

All we lack is the action to actually spend the money to put those into place.

我們所缺乏的其實是花費經費並將上述辦法付諸實行的行動，

Instead, we spend our time talking.

而不是說說空話而已。

But nevertheless, that's not what I'm going to talk to you about tonight.

不過，這並不是今晚我所要討論的主題。

What I'm going to talk to you about tonight is stuff we might do if we did nothing.

今晚我想告訴各位的是，我們除了袖手旁觀之外，還有什麼其他的選擇。

And it's this stuff in the middle here, which is what you do

圖中中間這部份便是我們所要做的

if you don't stop the emissions quickly enough.

除了減少溫室氣體排放以外的替代方案。

And you need to deal -- somehow break the link between human actions

我們必須試著切斷人類造成氣候變遷的行為

that change climate, and the climate change itself. And that's particularly important

以及氣候變遷本身之間的連結性。這是相當重要的，

because, of course, while we can adapt to climate change --

因為，我們當然可以適應氣候變遷

and it's important to be honest here, there will be some benefits to climate change.

而且老實說，氣候變遷也將會帶來一些益處。

Oh, yes, I think it's bad. I've spent my whole life working to stop it.

喔，是的。我知道它會造成的災害。阻止氣候變遷是我ㄧ生的志業，

But one of the reasons it's politically hard is there are winners and losers -- not all losers.

但其中是有政治上的難處的，因為結果難免有輸有贏-而非全是輸家。

But, of course, the natural world, polar bears.

不過當然，自然中像是北極熊啊，

I spent time skiing across the sea ice for weeks at a time in the high Arctic.

-我曾深入北極，花了幾週時間滑雪橫跨北極海冰了解這些極地生物-

They will completely lose.

這些生物將會一敗塗地，

And there's no adaption.

他們絲毫沒有適應的機會。

So this problem is absolutely soluble.

回過頭來說吧，氣候變遷的問題是絕對可解決的。

This geo-engineering idea, in it's simplest form, is basically the following.

這個地球工程的概念，簡單來說是這樣的:

You could put signed particles, say sulfuric acid particles -- sulfates --

我們將利用粒子，例如硫酸粒子-硫酸鹽-

into the upper atmosphere, the stratosphere,

置入大氣層上部的平流層，

where they'd reflect away sunlight and cool the planet.

利用這些粒子折射太陽光並達到冷卻地球的作用。

And I know for certain that that will work.

我確信這是可行的方法。

Not that there aren't side effects, but I know for certain it will work.

雖然會有些副作用，但是這絕對可行。

And the reason is, it's been done.

因為其實已有前例了。

And it was done not by us, not by me, but by nature.

但並不是人類的作為，而是大自然的造化。

Here's Mount Pinatubo in the early '90s. That put a whole bunch of sulfur

這是菲律賓品納土玻火山在90年代的爆發情況，當時大量的硫磺氣

in the stratosphere with a sort of atomic bomb-like cloud.

隨著蕈狀雲衝入平流層，

The result of that was pretty dramatic.

造成相當戲劇化的結果。

After that, and some previous volcanoes we have, you see

與過去其它火山爆發相似，品納土玻火山爆發後，

a quite dramatic cooling of the atmosphere.

各位可以看到大氣圈的溫度急遽下降。

So this lower bar is the upper atmosphere, the stratosphere,

下面的圖表是大氣層上部的狀況，也就是平流層，

and it heats up after these volcanoes.

火山爆發後的溫度上升。

But you'll notice that in the upper bar, which is the lower atmosphere

但各位會注意到在上面的圖表，也就是大氣層下部

and the surface, it cools down because we shielded the atmosphere a little bit.

及地表上的溫度因為大氣層受遮蔽的關係而下降。

There's no big mystery about it.

原理說穿了其實很簡單，

There's lots of mystery in the details, and there's some bad side effects,

當然有很多細節部份需要研究，同時也有些副作用，

like it partially destroys the ozone layer -- and I'll get to that in a minute.

像是對部分臭氧層造成破壞等等-這我等下還會提到。

But it clearly cools down.

但其效果是無庸置疑的，

And one other thing: it's fast.

而且見效極快。

It's really important to say. So much of the other things that we ought to do,

這是極為重要的。其它方案，

like slowing emissions, are intrinsically slow, because it takes time

如減緩溫室氣體排放等，本質上即較為緩慢，

to build all the hardware we need to reduce emissions.

因必須先建構相關必須的硬體。

And not only that, when you cut emissions, you don't cut concentrations,

還有另外一個重點是，減緩排放並無法直接降低既有的溫室氣體濃度。

because concentrations, the amount of CO2 in the air,

溫室氣體濃度，也就是空氣中二氧化碳的數量，

is the sum of emissions over time.

是長久以來累積的結果，

So you can't step on the brakes very quickly.

因此很難在短時間有顯著的改善。

But if you do this, it's quick.

但如果利用地球工程，很快便能有立竿見影之效。

And there are times you might like to do something quick.

這對於現階段來說是十分有幫助的。

Another thing you might wonder about is, does it work?

各位或許對於這項工程還存有一些懷疑，

Can you shade some sunlight and effectively compensate for the added CO2,

像是我們真的有辦法遮蔽陽光，有效彌補大氣中過多的二氧化碳，

and produce a climate sort of back to what it was originally?

並且使氣候回復成過往的樣子嗎?

And the answer seems to be yes.

答案似乎是肯定的。

So here are the graphs you've seen lots of times before.

這些圖表各位應該都看過很多次了。

That's what the world looks like, under one particular climate model's view,

這是地球在特定氣候模型下的面貌，

with twice the amount of CO2 in the air.

空氣中的二氧化碳為正常值的兩倍。

The lower graph is with twice the amount of CO2 and 1.8 percent less sunlight,

下方的圖表則是同樣兩倍的二氧化碳濃度，但光照減少1.8%，

and you're back to the original climate.

很明顯地，氣候將回復正常。

And this graph from Ken Caldeira. It's important to say came, because

這是氣候學家卡爾戴拉所作的圖表。各位或許不知道，

Ken -- at a meeting that I believe Marty Hoffart was also at in the mid-'90s --

90年代中期，卡爾戴拉出席了一場會議，另一位氣候學家馬蒂霍法也在，

Ken and I stood up at the back of the meeting and said,

我與卡爾戴拉站在會場後面勸說，

"Geo-engineering won't work."

「地球工程是沒有效的。」

And to the person who was promoting it said,

然後又跟那位提倡地球工程的學者解釋，

"The atmosphere's much more complicated."

「大氣層比我們想像的還要複雜。」

Gave a bunch of physical reasons why it wouldn't do a very good compensation.

然後列舉一大堆物理學上的理由來駁斥地球工程的做法。

Ken went and ran his models, and found that it did.

卡爾戴拉後來實際跑了模型，然後發現原來地球工程真的可行。

This topic is also old.

這個議題其實相當古老。

That report that landed on President Johnson's desk when I was two years old --

美國的詹森總統曾看過一份報告，那是在我兩歲的時候，

1965.

也就是1965年。

That report, in fact, which had all the modern climate science --

該份報告其實涵蓋了現代所有氣候科學的理論，

the only thing they talked about doing was geo-engineering.

而其中唯一提到的做法就是地球工程，

It didn't even talk about cutting emissions,

甚至沒有提到減少溫室氣體排放，

which is an incredible shift in our thinking about this problem.

這對氣候變遷的思考上提供了另一個新方向。

I'm not saying we shouldn't cut emissions.

這並不是說我們不該減少溫室氣體排放，

We should, but it made exactly this point.

我們應該減少氣體排放，但同時地球工程應也視為重點之一。

So, in a sense, there's not much new.

所以某方面來說，我們對氣候變遷早有解決之道。

The one new thing is this essay.

這篇論文倒是最近才提出的。

So I should say, I guess, that since the time of that original President Johnson report,

或許我應該說，自從第一份詹森總統報告、

and the various reports of the U.S. National Academy --

以及其他美國國家科學院於

1977, 1982, 1990 -- people always talked about this idea.

1977、1982、及1990研究報告出版後，人們便不斷地討論這個構想。

Not as something that was foolproof, but as an idea to think about.

不是說這個構想是萬無一失的，但至少值得一試。

But when climate became, politically, a hot topic -- if I may make the pun --

但當氣候成為了政治上的「火熱」議題-這算是個雙關語-

in the last 15 years, this became so un-PC, we couldn't talk about it.

在最近15年來，這個構想忽然就被打入冷宮，

It just sunk below the surface. We weren't allowed to speak about it.

就這樣子石沉大海，成為了一個禁忌的話題。

But in the last year, Paul Crutzen published this essay

但就在去年，諾貝爾化學獎得主克魯岑出版了這篇論文，

saying roughly what's all been said before: that maybe, given our very slow rate

概括性地整理過去提出的種種論點:鑒於改善氣候變遷的進度

of progress in solving this problem and the uncertain impacts,

十分緩慢，而影響尚不確定等等，

we should think about things like this.

我們應該認真考慮地球工程的可行性。

He said roughly what's been said before.

這其實算是舊瓶裝新酒。

The big deal was he happened to have won the Nobel prize for ozone chemistry.

但因其研究臭氧化學獲頒諾貝爾獎，

And so people took him seriously when he said we should think about this,

克魯岑的話在人們心中自然較具份量，

even though there will be some ozone impacts.

雖然地球工程對於臭氧仍有其衝擊，

And in fact, he had some ideas to make them go away.

但他甚至提出可能的化解之道。

There was all sorts of press coverage, all over the world,

克魯岑的理論被全球媒體大肆報導，

going right down to "Dr. Strangelove Saves the Earth," from the Economist.

著名的經濟學人雜誌甚至以「奇愛博士拯救地球」為文章標題。

And that got me thinking. I've worked on this topic on and off,

這讓我想到，自己過去斷斷續續地研究這項議題，

but not so much technically. And I was actually lying in bed thinking one night.

但從未深入了解之中的技術環節。一天晚上，我躺在床上思考，

And I thought about this child's toy -- hence, the title of my talk --

我忽然想到這個玩具，也就是我演講名稱的由來。

and I wondered if you could use the same physics that makes that thing spin 'round

我想，有沒有辦法運用與光熱轉輪旋轉相同的物理原理，

in the child's radiometer, to levitate particles into the upper atmosphere

讓粒子懸浮至上部大氣層

and make them stay there.

而不會落下。

One of the problems with sulfates is they fall out quickly.

硫酸鹽的一個問題是飄落快速，

The other problem is they're right in the ozone layer,

並且停留於臭氧層，

and I'd prefer them above the ozone layer.

我則希望硫酸鹽的位置保持於臭氧層上方。

And it turns out, I woke up the next morning, and I started to calculate this.

隔天早上，我開始進行一些計算。

It was very hard to calculate from first principles. I was stumped.

我發現使用第一原理計算過於困難，可以說寸步難行。

But then I found out that there were all sorts of papers already published

不過後來我發現這方面的計算早有許多相關論文出版，

that addressed this topic because it happens already in the natural atmosphere.

因為其實大氣層已有類似的現象。

So it seems there are already fine particles

自然中有許多懸浮粒子

that are levitated up to what we call the mesosphere, about 100 kilometers up,

上升至大約離我們100公里的中氣層，

that already have this effect.

產生類似的效應。

I'll tell you very quickly how the effect works.

我會簡短地告訴各位其運作方式。

There are a lot of fun complexities

其中有許多引人入勝的複雜細節，

that I'd love to spend the whole evening on, but I won't.

讓我很想用整個晚上的時間深入討論，不過這當然不可能。

But let's say you have sunlight hitting some particle and it's unevenly heated.

簡單來說，太陽光線撞擊粒子，使得粒子受熱不均。

So the side facing the sun is warmer; the side away, cooler.

面向太陽的球面溫度較高，反之則較低。

Gas molecules that bounce off the warm side

氣體分子碰到面向太陽的球面反彈時，

bounce away with some extra velocity because it's warm.

彈離的速度會因為溫度較高的關係而加快，

And so you see a net force away from the sun.

因此將造成遠離太陽的淨力，

That's called the photophoretic force.

也就是所謂的光泳力。

There are a bunch of other versions of it that I and some collaborators

我與其他同事還想出一些其他

have thought about how to exploit.

不同的運作方式。

And of course, we may be wrong --

當然，我們可能是錯的。

this hasn't all been peer reviewed, we're in the middle of thinking about it --

我們的構想尚未受深入檢視，也不盡完整，

but so far, it seems good.

但以目前的結果來說，它的可行性十分的高

But it looks like we could achieve long atmospheric lifetimes --

並可大幅延長大氣層的壽命。

much longer than before -- because they're levitated.

因為受懸浮作用的關係，

We can move things out of the stratosphere into the mesosphere,

我們可將分子將從平流層升至中氣層，

in principle solving the ozone problem.

使得臭氧問題獲得改善。

I'm sure there will be other problems that arise.

當然，我知道會有其他問題產生。

Finally, we could make the particles migrate to over the poles,

最後，我們可將粒子遷移至極地上空，

so we could arrange the climate engineering so it really focused on the poles.

將地球工程的重點放在極地區域，

Which would have minimal bad impacts in the middle of the planet,

使得地球其他人口較多的區域

where we live, and do the maximum job of what we might need to do,

受到的衝擊減至最小，

which is cooling the poles in case of planetary emergency, if you like.

同時讓兩極的溫度冷卻，避免地球暖化危機。

This is a new idea that's crept up that may be, essentially,

這個慢慢浮現的新構想，有可能會比

a cleverer idea than putting sulfates in.

純粹使用硫酸鹽來的有效。

Whether this idea is right or some other idea is right,

不過，不論這個構想或其他構想可行與否，

I think it's almost certain we will

我幾乎確信人類

eventually think of cleverer things to do than just putting sulfur in.

總有一天會開發出凌駕於使用硫磺的工程法。

That if engineers and scientists really turned their minds to this,

只要工程師以及科學家有心研發，

it's amazing how we can affect the planet.

地球改善的程度將超乎想像。

The one thing about this is it gives us extraordinary leverage.

同時，人類文明的進步也讓我們有更多著力點，

This improved science and engineering will, whether we like it or not,

科技以及工程上的不斷突破，

give us more and more leverage to affect the planet,

使我們更有能力去改善我們的地球、

to control the planet,

掌握我們的地球、

to give us weather and climate control -- not because we plan it,

並控制天氣以及氣候。

not because we want it, just because science delivers it to us bit by bit,

因為這是科技進程的必然結果，

with better knowledge of the way the system works

因為我們將更為了解氣候系統運作，

and better engineering tools to effect it.

也將有更好的工程法來進行改善。

Now, suppose that space aliens arrived.

現在讓我們想像外星人突然抵達地球，

Maybe they're going to land at the U.N. headquarters down the road here,

不管他們降落於附近的聯合國總部

or maybe they'll pick a smarter spot --

或是其他更好停車的地方。

but suppose they arrive and they give you a box.

外星人贈與我們一個寶盒，

And the box has two knobs.

上面有兩個旋鈕。

One knob is the knob for controlling global temperature.

一個旋鈕控制著全球各地的溫度，

Maybe another knob is a knob for controlling CO2 concentrations.

而另一個旋鈕控制著二氧化碳濃度。

You might imagine that we would fight wars over that box.

各位可以想見，各國將不惜發動戰爭，

Because we have no way to agree about where to set the knobs.

因為我們對於如何控制這個寶盒將不會有共識。

We have no global governance.

我們並沒有全球性的政府機關，

And different people will have different places they want it set.

不同的利益團體會希望寶盒設置於不同的地點。

Now, I don't think that's going to happen. It's not very likely.

當然我不認為這樣的天方夜譚會發生，

But we're building that box.

不過人類的確正在建構這個寶盒。

The scientists and engineers of the world

世界各地的科學家以及工程師

are building it piece by piece, in their labs.

正在他們的實驗室裡慢慢地使氣候控制成為可能，

Even when they're doing it for other reasons.

當然或許裡面有些人並不自覺。

Even when they're thinking they're just working on protecting the environment.

他們可能只是單純想著要保護我們的環境，

They have no interest in crazy ideas like engineering the whole planet.

對於控制全球氣候這個瘋狂的想法毫無興趣，

They develop science that makes it easier and easier to do.

但其研發的科技已讓氣候控制的技術逐漸成熟。

And so I guess my view on this is not that I want to do it -- I do not --

我個人對於控制氣候並無偏好，

but that we should move this out of the shadows and talk about it seriously.

但我認為該是時候將這個議題放上檯面進行嚴肅的討論了。

Because sooner or later, we'll be confronted with decisions about this,

總有一天，我們會面對這樣的決定，

and it's better if we think hard about it,

所以我們最好未雨綢繆，

even if we want to think hard about reasons why we should never do it.

包括思考人類究竟該不該進行氣候控制。

I'll give you two different ways to think about this problem that are the beginning

關於這個議題

of my thinking about how to think about it.

我要提供個人的兩個不同思考方向。

But what we need is not just a few oddballs like me thinking about this.

我們需要的不只是幾個像我一樣的古怪科學家在象牙塔中做研究，

We need a broader debate.

而是更為廣泛的討論。

A debate that involves musicians, scientists, philosophers, writers,

我們可邀請關注這項議題的音樂家、科學家、哲學家、作家等等

who get engaged with this question about climate engineering

對氣候控制進行討論，

and think seriously about what its implications are.

並思考其可能涵蓋的其他相關議題。

So here's one way to think about it,

我提供給各位的第一個思考方向，

which is that we just do this instead of cutting emissions because it's cheaper.

便是有了地球工程，人類是否不再需要減少溫室氣體排放。

I guess the thing I haven't said about this is, it is absurdly cheap.

我好像還沒跟各位強調地球工程的費用有多低廉。

It's conceivable that, say, using the sulfates method or this method I've come up with,

根據計算，如果利用硫酸鹽或剛剛我提到的懸浮粒子，

you could create an ice age at a cost of .001 percent of GDP.

只需花費大約0.0001%的GDP，便能以人工的方式創造出另一個冰川期。

It's very cheap. We have a lot of leverage.

價格低廉而實惠。

It's not a good idea, but it's just important. (Laughter)

它有其危險性，但對於改善氣候變遷的確有其重要性。

I'll tell you how big the lever is: the lever is that big.

而我告訴各位，地球工程法影響地球的程度是十分巨大的。

And that calculation isn't much in dispute.

這些都是已經過實際計算的數據，

You might argue about the sanity of it, but the leverage is real. (Laughter)

各位可能會懷疑這是瘋狂科學家的想法，但其影響是貨真價實的。(笑聲)

So because of this, we could deal with the problem

另外一個解決問題的方向是，

simply by stopping reducing emissions,

單純進行溫室氣體排放的減量，

and just as the concentrations go up, we can increase

而隨著二氧化碳濃度提高，

the amount of geo-engineering.

我們再依程度逐步進行地球工程。

I don't think anybody takes that seriously.

我不認為這個方向值得認真思考，

Because under this scenario, we walk further and further away

因為如此一來，我們將逐漸與

from the current climate.

目前的氣候漸行漸遠。

We have all sorts of other problems, like ocean acidification

除了氣候變遷等，地球目前仍有其他如海洋酸化等

that come from CO2 in the atmosphere, anyway.

因二氧化碳濃度過高間接產生的問題。

Nobody but maybe one or two very odd folks really suggest this.

大概只有一兩個學者提出這個理論方向。

But here's a case which is harder to reject.

我再舉另一個令人不得不服氣的例子。

Let's say that we don't do geo-engineering, we do what we ought to do,

假如說我們拒絕地球工程，進行傳統的方式，

which is get serious about cutting emissions.

也就是嚴格執行減少氣體排放，

But we don't really know how quickly we have to cut them.

我們將無法對於減少排放量訂立一個明確的目標。

There's a lot of uncertainty about exactly how much climate change is too much.

目前人類對於氣候變遷可容忍的限度仍無定論。

So let's say that we work hard, and we actually don't just tap the brakes,

如果我們嚴格執行減碳，

but we step hard on the brakes and really reduce emissions

徹底降低溫室氣體排放量，

and eventually reduce concentrations.

讓空氣中的二氧化碳濃度降低，

And maybe someday -- like 2075, October 23 --

皇天不負苦心人，終於在某個日子，就說2075年10月23日好了，

we finally reach that glorious day where concentrations have peaked

我們渡過了二氧化碳濃度的巔峰期，

and are rolling down the other side.

而二氧化碳濃度終於開始降低。

And we have global celebrations, and we've actually started to -- you know,

各國開始進行全球性的慶祝，

we've seen the worst of it.

因為苦日子終於過去了。

But maybe on that day we also find that the Greenland ice sheet

但或許在同一天，我們發現格陵蘭的冰原面積

is really melting unacceptably fast, fast enough to put meters of sea level on

正以無法接受的速度快速融解，爾後一百年間，

the oceans in the next 100 years,

全球平均海拔將與海平面同高，

and remove some of the biggest cities from the map.

而許多重大城市將從地圖上消失。

That's an absolutely possible scenario.

這是絕對有可能發生的。

We might decide at that point that even though geo-engineering was uncertain

那時我們可能才意識到，雖然地球工程效用尚不明朗，

and morally unhappy, that it's a lot better than not geo-engineering.

且道德上還有許多疑慮，但似乎仍比減碳要好。

And that's a very different way to look at the problem.

這是另外一個非常不同的觀點。

It's using this as risk control, not instead of action.

地球工程被視為風險控管的手段，而非傳統減碳的替代方案。

It's saying that you do some geo-engineering for a little while

好比只執行地球工程一段時間，

to take the worst of the heat off, not that you'd use it as a substitute for action.

並且只以稍微舒緩暖化的壓力為前提。

But there is a problem with that view.

但這樣的觀點有個問題，

And the problem is the following:

也就是說，

knowledge that geo-engineering is possible makes

既然知道還有地球工程這一手段，

the climate impacts look less fearsome,

會讓氣候變遷不再那麼令人聞之色變，

and that makes a weaker commitment to cutting emissions today.

因此會讓減碳難以徹底執行。

This is what economists call a moral hazard.

這就是經濟學家所謂的道德危機。

And that's one of the fundamental reasons that this problem is so hard to talk about,

這其實是這個問題令人難以啟齒的基本原因之一，

and, in general, I think it's the underlying reason

同時我想也是為何

that it's been politically unacceptable to talk about this.

地球工程法在政治上無法被接受的潛在因素。

But you don't make good policy by hiding things in a drawer.

但將問題隱而不談，在制訂對策時是毫無助益的。

I'll leave you with three questions, and then one final quote.

我最後將請各位思考三個問題，並引用一段文章作結。

Should we do serious research on this topic?

我們是否該對此議題進行嚴肅研究?

Should we have a national research program that looks at this?

我們是否應該制定國家性的研究計畫深入剖析?

Not just at how you would do it better,

研究並不僅限於如何改善地球工程，

but also what all the risks and downsides of it are.

同時也包括其風險與副作用。

Right now, you have a few enthusiasts talking about it, some in a positive side,

目前有許多人關注這項議題，有些人十分看好，

some in a negative side -- but that's a dangerous state to be in

有些則持負面觀感。這樣的狀況其實是相當危險的。

because there's very little depth of knowledge on this topic.

因為我們對這個議題並無深入的了解，

A very small amount of money would get us some.

投注小量資金進行相關研究對了解這項議題將有實質的幫助。

Many of us -- maybe now me -- think we should do that.

許多人，也包括我自己，認為應該進行地球工程，

But I have a lot of reservations.

但我也有一些保留，

My reservations are principally about the moral hazard problem,

主要的顧慮就是剛提到的道德危機，

and I don't really know how we can best avoid the moral hazard.

道德危機似乎是無可避免的，

I think there is a serious problem: as you talk about this,

我認為這是伴隨地球工程而來的一個嚴重的問題，

people begin to think they don't need to work so hard to cut emissions.

人們會開始認為節能減碳其實並沒有那麼迫切。

Another thing is, maybe we need a treaty.

另一方面來說，簽訂條約似乎有其必要性，

A treaty that decides who gets to do this.

以條約的方式決定誰全盤負責。

Right now we may think of a big, rich country like the U.S. doing this.

現在我們可能會想說應該由世界大國，像是美國來負責，

But it might well be that, in fact, if China wakes up in 2030 and realizes

但中國也有可能於2030年忽然覺醒，

that the climate impacts are just unacceptable,

體認到氣候變遷帶來的衝擊是無法接受的。

they may not be very interested in our moral conversations about how to do this,

他們可能不想跟我們一樣從長計議，

and they may just decide they'd really rather have a geo-engineered world

想直接進行地球工程法

than a non-geo-engineered world.

而不採用保守的節能減碳。

And we'll have no international mechanism to figure out who makes the decision.

屆時我們將沒有任何的國際機制進行相關決議。

So here's one last thought, which was said much, much better

最後我想再提供給各位一個想法，這是25年前，

25 years ago in the U.S. National Academy report than I can say today.

美國國家科學院的報告中便已明白闡述的一個概念。

And I think it really summarizes where we are here.

我認為這個想法描述了我們目前的真實處境。

That the CO2 problem, the climate problem that we've heard about,

報告指出，現今的二氧化碳問題、氣候變遷問題

is driving lots of things -- innovations in the energy technologies

正不斷激勵能源科技的創新，

that will reduce emissions --

而使得溫室氣體排放逐漸降低。

but also, I think, inevitably, it will drive us towards thinking about climate

但同時這些問題也無可避免地促使我們思考

and weather control, whether we like it or not.

進行天候控制的必要性。

And it's time to begin thinking about it,

該是時候我們好好的審視這個議題，

even if the reason we're thinking about it is to construct arguments

或許試著以正反不同角度進行深度討論，

for why we shouldn't do it.

思索地球工程的可行與否。

Thank you very much.

謝謝各位。