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

翻译人员: Danny Xiao 校对人员: Amy Zerotus

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

大家都读过很多有关气候变化的文章，

and here's yet another New York Times article,

现在给大家展示的这篇文章源于《纽约时报》，

just like every other darn one you've seen.

和你们之前看到的大同小异。

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

文章的内容和你们原来看的没什么两样。

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

小标题的数量都一模一样。

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

那这篇文章又有什么独特之处呢？可能是它写于1953年吧。

And the reason I'm saying this

我之所以这么说

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

是因为你们以为气候问题只是最近才提出来的。

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

人们这些年才开始意识到气候变化这一问题，

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

而且，人们开始真正采取行动，比如签订《京都议定书》，以及加州州长（施瓦辛格）的环保倡议，

we may be on the road to a solution.

我们好像已经上路了。

The fact is -- uh-uh.

事实上是：哼哼，还早着呢。

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

人类意识到这个问题已经有50年了，时间要看你怎么算。

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

过去的十几年里我们不断地讨论这个问题。

And we've accomplished close to zip.

但是我们解决的问题几乎等于0。

This is the growth rate of CO2 in the atmosphere.

这张图表反映的是大气中二氧化碳含量上升的情况。

You've seen this in various forms,

大家已经看过各式各样反映二氧化碳含量上升的表格，

but maybe you haven't seen this one.

但是你们可能还没有见过这样的一个表格。

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

这张表格反映的是我们的排放量在增加，

And that it's accelerating even faster

而且，增加的速度甚至比我们

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

前几年想的最坏情况还要快。

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

红线显示的是很多怀疑论者所持的观点，他们认为

the environmentalists only put in the projections

环境学家提出这些问题

to make the projections look as bad as possible,

是想把问题弄得看起来尽可能糟。

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

他们认为排放量绝不会有红线显示得那么快。

But in fact, they're growing faster.

但是事实上，排放量增长得比红线还快。

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

这里有一些10天前的数据，

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

这些数据显示了今年北冰洋的最小冰量，这也是有史以来的最小值。

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

北冰洋冰块融化速度比预想的要快。

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

尽管各行各业的专家像我一样成天飞来飞去，

burning jet fuel, and politicians signing treaties --

飞机也耗了不少油，政治家也在签署各项条约，

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

实际上你们可能发现最终结果是负面的，

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

因为我们浪费了很多飞机燃料。（笑）

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

不，不！我们现在真正要做的是把刹车片放到

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

我们庞大的经济体上——这个家伙惯性很大——我们过去就几乎没有真正启动过。

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

事实上我们在行动。但成果不大。

I don't want to depress you too much.

我不想太打击你们。

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

问题是绝对可以解决的，而且解决的方式很便宜。

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

我说“便宜”指的是相对于军费开销，而不是动用医疗保险的资金。

Cheap meaning a few percent of GDP.

“便宜”指的是占用很少一部分GDP。

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

有这样的概念非常重要。

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

问题是可以解决的，我们要解决的问题，比如说

dealing with electricity production,

是发电

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

发电产生的二氧化碳占到了43%左右，也导致二氧化碳排放量的上升。

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

我们解决这一问题的方法很多也很完美，比如说节约、

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

利用风能、核能，从而降低因烧煤而带来的二氧化碳。

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

但是上述的方法都需要调配大量的人员和安排大量的工作。

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

我们缺少的是投入资金把上述方案付诸行动。

Instead, we spend our time talking.

我们只是在空谈。

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

但是这不是今晚我要和你们讨论的话题。

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

今晚我打算和大家说的是如果我们过去无所作为现在还能做什么。

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

如果你们不很快地停止排放

if you don't stop the emissions quickly enough.

那中间显示的就是大家可以做的。

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

大家要解决的就是——如何打破造成气候变化的人类活动与

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

气候变化本身的联系。这一点非常重要，

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

与此同时我们也能适应气候变化。

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

老实说——气候变化也会带来一些好处。

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

当然我本人认为气候变化很糟，所以我花毕生精力来阻止情况继续恶化。

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

但是我们面临一个两难的问题是总要有赢家和输家——不全是输家。

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

但是当然，大自然的一些动物，比如说北极熊又有新的问题：

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

（我曾经花了几个星期在北极高处的冰川上滑雪）

They will completely lose.

北极熊会彻底输掉，

And there's no adaption.

因为北极上不会有生物适应。

So this problem is absolutely soluble.

但是，如我说讲的，气候变化是肯定可以解决的。

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

答案就是地球工程学的思想，简单地说，就是如下的观点：

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

你们可以把带电粒子，比如说硫酸粒子——硫酸盐——

into the upper atmosphere, the stratosphere,

放入较高的大气层，也就是平流层，

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

在平流层这些粒子可以反射阳光，帮地球降温。

And I know for certain that that will work.

据我所知，这种方法是肯定有效的。

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

而且不会有负作用。我为什么这么肯定地说这种方法会成功呢？

And the reason is, it's been done.

理由是：这种方法已经被实践过了。

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

不是我们做的，也不是我做的，而是大自然做的。

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

这是90年代初的皮纳图博火山喷发，产生了有一中类似原子弹爆炸的云

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

把大量的硫带入了平流层。

The result of that was pretty dramatic.

结果非常具有戏剧效果。

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

自从那以后，加上之前的一些火山喷发，你们看

a quite dramatic cooling of the atmosphere.

大气层温度惊人的下降。

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

下面这根线代表较高层的大气层（平流层）的温度

and it heats up after these volcanoes.

火山爆发后平流层温度上升。

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

但是请注意上面这根线，代表底层大气的温度

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

也就是地球表面的温度下降了，因为我们稍微遮盖了一下地球。

There's no big mystery about it.

其实，这里没有什么大的秘密。

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

虽然细节上有很多谜团，也有一些负面影响，

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

比如说可能会部分破坏臭氧层——我待会儿会讲这个问题。

But it clearly cools down.

但是很明显的是：温度下降了！

And one other thing: it's fast.

而且，温度改变得很快！

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

这非常重要。还有很多其他事情我们应该行动，

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

比如说减少排放量，这本来就是一个很慢的过程

to build all the hardware we need to reduce emissions.

因为我们还要花时间来建各种设备来减少排量。

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

不仅如此，当你减少排量的时候，你并没有减少浓度。

because concentrations, the amount of CO2 in the air,

因为浓度的定义是空气中CO2的总量，

is the sum of emissions over time.

是长期排放的总和。

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

所以我们不能快速地停下来。

But if you do this, it's quick.

但是如果你们这样做，就会很快。

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

很多情况下你们都希望能够快速地完成一件事。

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

你们可能会担心另外一件事：这个方法有效吗？

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

真的可以遮挡阳光并且有效地抵消额外的CO2,

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

而且可以产生一种气候条件去补偿它本来的来源吗？

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.

这些是你们过去看过无数次的表格。

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

在这样的一种特定的气候模式的观点下，世界看起来总是一样

with twice the amount of CO2 in the air.

因为我们的空气中有两倍的CO2总量。

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

下面的表格显示的是两倍的CO2和不到1.8%的阳光，

and you're back to the original climate.

现在大家回到了最原始的气候状态。

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

这张表格来自肯-卡德拉。说明它的来源非常重要，因为

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

那是在90年代中的一次会议上，马丁·霍弗特也在

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

肯和我站在会议室后面说，

"Geo-engineering won't work."

“地球工程学不能解决问题。”

And to the person who was promoting it said,

然后他又对推广地球工程学的人说，

"The atmosphere's much more complicated."

“大气层远比我们想的复杂。”

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

然后他又给出了物理学上一大堆理由来说明为什么用上述方法不能很好地补偿。

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

肯继续证明并且动用了他的模型，结果发现是可以的。

This topic is also old.

这个话题也有些陈旧了。

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

当年递到约翰逊总统桌子上的那份报告，那时我只有两岁，

1965.

1965年

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

实际上那份报告已经包含了所有现代气候科学知识——

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

他们实际上说的唯一一个问题是地球工程学。

It didn't even talk about cutting emissions,

甚至没有讨论减排，

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

这是我们在考虑解决这一问题上思想上难以置信的转变。

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

我不是说我们不应该减排。

We should, but it made exactly this point.

我们应该减排，但是这不是重点。

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

所以从某种意义上说，并没有什么新东西。

The one new thing is this essay.

唯一的新东西是这篇文章。

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

所以我想我应该说，自从约翰逊总统桌上放了那份最初的报道以来，

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

美国国立研究院的各种各样的报告——

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

1977.1982，1990——人们总是在谈论这个观点。

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

这不是一个万无一失的计划，但这的确是一个值得思考的观点。

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

但是当气候成为政治上的热门话题——请允许我用这个双关语——

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

在过去15年，气候问题变得不政治正确了，我们不能谈及这一问题。

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

这个观点也就石沉大海了。我们不允许再谈论这一问题。

But in the last year, Paul Crutzen published this essay

但是在去年，保罗·克鲁岑发表了这篇文章，

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

文章的大概内容和过去大体相同：遮挡的方法可能会让我们在

of progress in solving this problem and the uncertain impacts,

解决问题时速度放慢，而且有不确定的影响，

we should think about things like this.

但是我们应该从这个角度来考虑这一问题。

He said roughly what's been said before.

他的观点和过去的大体相同。

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

不同的是鉴于他在臭氧层化学上的研究，他获得了诺贝尔奖

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

所以当他说我们应该思考这个问题的时候很多人开始重视了，

even though there will be some ozone impacts.

即使这对臭氧层有所影响。

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

事实上，他还提出了一些办法来减少，甚至消除，对臭氧层的影响。

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

过去全世界有各种各样的新闻报道，

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

比如说《经济学家》的“奇爱博士拯救地球”。

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

那篇文章让我思考——我断断续续研究过这个话题，

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

但是不是非常专研——实际上我就躺在床上想了一晚上。

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

我也考虑过 小孩的玩具——因此，这就是我演讲的题目——

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

我在想我们能不能用那种可以让物质在小孩子的辐射测量仪中旋转起来的同样的物理学原理

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

把粒子送入高层大气，

and make them stay there.

并且让粒子一直待在那儿。

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

硫酸盐的一个问题是他们会很快下落。

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

另外一个问题是他们就在臭氧层，

and I'd prefer them above the ozone layer.

我更愿意他们是在臭氧层之上。

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

第二天早上起来，我就开始计算。

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

要用基本原理来计算非常困难。我的计算被卡住了。

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

但是后来我发现已经有各种各样发表了的论文

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

就是要解决这个问题，因为问题已经在自然的大气层中产生了。

So it seems there are already fine particles

似乎已经有细微的粒子

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

升到了我们所说的中间层，大约100千米以上——

that already have this effect.

而且已经有了这种效应。

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

我会很快地告诉你们这种效应是如何产生的。

There are a lot of fun complexities

这里面有很多很有趣的复杂理论

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

我可以花整个晚上来讲这个问题，但是我没有那么多时间。

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

设想：阳光照在这些粒子上，而且受热不均

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

所以面对太阳的一面要暖和些，背对太阳的一面要凉快些。

Gas molecules that bounce off the warm side

暖和的一面反射大气分子，

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

因为那面要热一些，速度又会更快。

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

所以产生一种和太阳能相反的力，

That's called the photophoretic force.

叫做光泳力。

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

我和其他合作者还想了很多其他版本的解释

have thought about how to exploit.

我们思考过如何开发出来。

And of course, we may be wrong --

当然，我们可能错了——

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

这些都还没有完完全全审核过，我们还在思考——

but so far, it seems good.

但是到目前为止看起来还不错。

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

但是看起来我们已经可以延长环境寿命了——

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

比过去长很多——因为他们被送上了大气层。

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

我们也可以把这些物质从同温层送到中间圈，

in principle solving the ozone problem.

理论上可以解决臭氧空洞的问题。

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

我敢肯定这又会引发其他一些问题。

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

最后，我们可以让微粒移动到极地上空，

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

这样的话我们就可以把环境工程的问题集中在地球两极。

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

这一举措会对我们居住的地球中部地区产生最小的副作用，

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

因为地球中部是我们主要生活和工作的地方。

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

而且，这一举措可以预防地球的各种不测带来的影响，给两极降温。

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

这个一时心血来潮想出来的办法，

a cleverer idea than putting sulfates in.

或许比放硫酸盐还要好。

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

不管这个办法或者是其他的办法是否行得通，

I think it's almost certain we will

我认为我们最终肯定能

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

想出比放硫更好的办法。

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

如果工程师和科学家致力于此，

it's amazing how we can affect the planet.

我们将会奇迹般地改造我们的地球。

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

我们从中获得的是一个广阔的平台。

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

无论我们喜欢与否，先进的科学和工程学会

give us more and more leverage to affect the planet,

提供给我们越来越多的机会去改变我们的地球。

to control the planet,

掌控地球。

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

让我们控制天气和气候——这不是因为我们打算这么做，

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

也不是因为我们想要这么做，只是因为科学一步步地在把掌控权送到我们手中。

with better knowledge of the way the system works

当然也少不了对系统工作原理的深入了解

and better engineering tools to effect it.

和更好的工程学工具的帮助。

Now, suppose that space aliens arrived.

大家试想一下外星人来了——

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

他们可能打算在联合国总部着陆，

or maybe they'll pick a smarter spot --

他们也有可能降落到一个更高明的地方——

but suppose they arrive and they give you a box.

但是就设想他们到了之后给你一个盒子。

And the box has two knobs.

这个盒子有两个旋钮：

One knob is the knob for controlling global temperature.

第一个可以控制全球气温，

Maybe another knob is a knob for controlling CO2 concentrations.

或许第二个可以控制CO2的浓度。

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

可以想象我们会为那个盒子打得不可开交。

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

因为我们没法就控制哪个旋钮达成一致,

We have no global governance.

我们没有国际性政府。

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

而且每个人对于用哪个旋钮都有自己的想法。

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

我认为这不大可能发生。

But we're building that box.

但是我们在制造那个盒子。

The scientists and engineers of the world

各国的科学家和工程师们在他们的实验室里

are building it piece by piece, in their labs.

在一点点地建造盒子。

Even when they're doing it for other reasons.

他们可能这么做的初衷不是为此。

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

他们的想法可能是他们只是在努力保护环境。

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

他们对像控制地球一类的疯狂想法毫无兴趣。

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

他们的努力让这些疯狂的想法更加容易得以实现。

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

所以对于这个问题我的观点，不是我想去这么做——我不想——

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

但是我们应该摆脱思想的束缚，来好好探讨这个问题。

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

因为过不了多久我们就会面临这样一个抉择，

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

所以我们最好现在就好好想这个问题，

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

即使我们想思考为什么不可以做的原因。

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

我来抛砖引玉地讲两种思考这个问题的方法

of my thinking about how to think about it.

但这只是思考这个问题的开始。

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

我们不仅需要像我这样的几个怪胎来思考这个问题——

We need a broader debate.

我们还需要更广泛地讨论。

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

一场音乐家，科学家，哲学家，作家都参与的大辩论

who get engaged with this question about climate engineering

只要是把这个问题和气候工程学联系起来，

and think seriously about what its implications are.

并且仔细想过这所产生的影响即可。

So here's one way to think about it,

有这么一种思维方式，

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

相比而言，这个方法比减排要便宜得多，我们只用照着做就行了。

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

我上面漏掉的一点是，这个方法真的很便宜。

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

比如说，运用我想到的硫颗粒的办法或者是刚刚说的措施，

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

你可以只用GDP的十万分之一来造出一个冰河世纪，这是完全有可能的。

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

这非常便宜。我们有很多优势。

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

刚刚我讲的不是一个好主意，但是很重要。

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

我马上会告诉大家这种方法所达到的效果有多明显。

And that calculation isn't much in dispute.

而且计算的结果没有太大的分歧。

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

你可能会怀疑我大脑是否清醒，但是事实就是如此。（笑）

So because of this, we could deal with the problem

所以因为这一点，我们可以

simply by stopping reducing emissions,

只依靠减排来解决问题。

and just as the concentrations go up, we can increase

随着CO2浓度升高，我们也可以加强

the amount of geo-engineering.

地球工程学的应用。

I don't think anybody takes that seriously.

我认为不是所有人都当真。

Because under this scenario, we walk further and further away

因为在这种大背景下，我们干的事和解决当前气候问题

from the current climate.

越来越远。

We have all sorts of other problems, like ocean acidification

我们也还面临着其他各种各样的问题，比如说海水酸化，

that come from CO2 in the atmosphere, anyway.

而罪魁祸首是大气中的CO2。

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

可能也就一两个怪人认为这个方法可行。

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

我们不能回避这样一个问题。

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

这样来说吧，如果我们不从地球工程学的角度解决问题，按常规方法出牌，

which is get serious about cutting emissions.

也就是说把重心放在减排上。

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

但是我们真的不知道我们得多快才行。

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

至于气候变化的速度有多快还是个未知数。

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

如果真要走减排这条路，我们要做的不仅仅是轻踩刹车，

but we step hard on the brakes and really reduce emissions

我们应该急刹，真正做到减排，

and eventually reduce concentrations.

最后达到降低CO2浓度的目的 。

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

或许有朝一日——打个比方，2075年10月23日——

we finally reach that glorious day where concentrations have peaked

当那一天来临时，CO2浓度达到最高值，

and are rolling down the other side.

开始往下降。

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

全球可能都得开一回庆功宴。

we've seen the worst of it.

当然，我们也做了最坏的打算。

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

或许到那天我们发现格林兰岛的冰盖

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

在融化，而且速度非常之快，快到在未来100年内

the oceans in the next 100 years,

把海平面提高几米，

and remove some of the biggest cities from the map.

快到可以把一些大城市从地图上抹掉。

That's an absolutely possible scenario.

这一幕完全有可能出现。

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

我们可以这么来看，即使在运用地球工程学过程中有很多不确定因素，

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

人们也一时难以接受，但是也总比不用的好。

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

如果这样来看这个问题，事情就会大不一样。

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

实质上这是风险控制，不是代替其他措施。

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

也就是说你应用地球工程学做点事情，为地球降温，

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

而不是说把地球工程学当成其他措施的替代品。

But there is a problem with that view.

但是这样看也会有个问题。

And the problem is the following:

产生的问题如下：

knowledge that geo-engineering is possible makes

“地球工程学可以解决全球变暖”的观点

the climate impacts look less fearsome,

使得人们对气候变化没有了危机感。

and that makes a weaker commitment to cutting emissions today.

那样就会减弱大家对减排的责任感。

This is what economists call a moral hazard.

这就是经济学家所说的道德风险。

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

这也是为什么这个问题如何难以被讨论的根本原因之一，

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

而且我觉得这也正是

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

政治上不愿意提及这个问题的潜在原因。

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

但把事情藏起来并不能制定出好的政策。

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

最后，我提三个问题和一个引用的话作为结尾。

Should we do serious research on this topic?

第一个问题：我们是否应该认真的研究这个问题？

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

第二个问题：我们是否应该启动一个国家级的研究项目来探讨这个问题？

Not just at how you would do it better,

并不单单讨论如何做得更好，

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

还研究它可能产生的风险和不足。

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

现在我们只有少数热衷者在讨论这个问题，部分人持正面态度，

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

部分人持负面态度。但这正是一个极危险的处境，

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

因为关于这个问题深入的认识太少了。

A very small amount of money would get us some.

现在只需要少量的投入，就可以得到一些研究成果。

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

很多人——也许现在是我——认为我们应该这么做，

But I have a lot of reservations.

但我也有很多疑虑，

My reservations are principally about the moral hazard problem,

主要是关于道德风险的问题，

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

我真的想不出来如何避免道德风险。

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

我想这的确是一个很严重的问题，

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

因为人们会觉得更本没有必要那么努力地减排（地球工程学可以解决问题）。

Another thing is, maybe we need a treaty.

第三个问题是：也许我们需要制定一个条约，

A treaty that decides who gets to do this.

来决定这项任务由谁来完成。

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

现在我们可能认为像美国这样富有的大国应该去做，

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

但事实上，也许中国在2030年认识到

that the climate impacts are just unacceptable,

气候影响已经到了不可接受的地步，

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

而且他们可能没有我们这样的道德保守，

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

他们可能就决定更愿要一个地球工程学改造过的世界

than a non-geo-engineered world.

而不是一个没有地球工程学的世界。

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

到那时，我们会发现根本没有一套国际机制来决定谁来做最后的决定。

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

结束演讲前我还有最后一个观点，

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

这个观点在25年前的美国国家工程院的报告中就已经讲得很清楚了，

And I think it really summarizes where we are here.

我想它能够很好的概括我今天的演讲。

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

“我们所听到的气候问题，CO2问题，

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

正在推动很多能源技术的创新

that will reduce emissions --

来减少排放。”

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

但是，我想它也会毋庸置疑地推动我们思考

and weather control, whether we like it or not.

关于气候和天气控制的问题，不管我们喜欢与否。

And it's time to begin thinking about it,

我想是时候开始思考这个问题了，

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

即便只是为了找理由

for why we shouldn't do it.

证明我们为什么不能做。

Thank you very much.

谢谢。