Four hundred parts per million: that's the approximate concentration of CO2 in the air today.
百万分之四百，那是现今空气中二氧化碳的大约浓度。
What does this even mean? For every 400 molecules of carbon dioxide, we have another million molecules of oxygen and nitrogen.
那到底是什么意思？每400个二氧化碳的分子，就会有另外100万个氧和氮的分子。
In this room today, there are about 1,800 of us.
现在在这间房间中，我们大约有1800人。
Imagine just one of us was wearing a green shirt, and you're asked to find that single person.
想象一下，我们当中只有一人穿绿色上衣，你被要求去找到那一个人。
That's the challenge we're facing when capturing CO2 directly out of the air.
那就是现今我们想要直接捕获空气中的二氧化碳时所遇到的问题。
Sounds pretty easy, pulling CO2 out of the air. It's actually really difficult.
听起来挺简单的，把二氧化碳从空气中去除。其实真的很困难。
But I'll tell you what is easy: avoiding CO2 emissions to begin with.
但告诉各位什么很容易：一开始就避免排放二氧化碳。
But we're not doing that. So now what we have to think about is going back; pulling CO2 back out of the air.
但我们没有这么做。所以现在我们必须回过头去；把二氧化碳从空气中抽出来。
Even though it's difficult, it's actually possible to do this.
即使很困难，还是有可能做到的。
And I'm going to share with you today where this technology is at and where it just may be heading in the near future.
今天我要和各位分享的是这项技术的现况以及在不远的将来它可能的发展方向。
Now, the earth naturally removes CO2 from the air by seawater, soils, plants and even rocks.
地球本身自己就会把二氧化碳从空气中除去，通过海水、土壤、植物、甚至石头来做这件事。
And although engineers and scientists are doing the invaluable work to accelerate these natural processes,
虽然工程师和科学家都投入在加速这些自然过程的无价工作上，
it simply won't be enough. The good news is, we have more.
可是还不足够。好消息是，我们还有其他方法。
Thanks to human ingenuity, we have the technology today to remove CO2 out of the air using a chemically manufactured approach.
靠着人类的足智多谋，我们现在有技术可以把空气中的二氧化碳除去，利用化学反应的方法。
I like to think of this as a synthetic forest. There are two basic approaches to growing or building such a forest.
我愿意把它想成是一个合成森林。要种出或建造出这样的森林有两种基本的方式。
One is using CO2-grabbing chemicals dissolved in water.
第一是使用溶解在水中且能够抓取二氧化碳的化学物质。
Another is using solid materials with CO2-grabbing chemicals.
第二是使用固态材料，内含有能抓取二氧化碳的化学物质。
No matter which approach you choose, they basically look the same.
不论你选择哪一种方法，它们大体上看起来是一样的。
So what I'm showing you here is what a system might look like to do just this. This is called an air contactor.
我接着要给各位看做这件事的系统是什么样子的。这叫做空气接触器。
You can see it has to be really, really wide in order to have a high enough surface area to process all of the air required,
它必须要非常非常宽，这样才能有足够大的表面积来处理所有必要的空气，
because remember, we're trying to capture just 400 molecules out of a million.
因为，别忘了，我们在试着在一百万个分子中采集四百个分子。
Using the liquid-based approach to do this, you take this high surface area packing material,
如果要用液体方法来采集，你就要用这大表面积的包材，
you fill the contactor with the packing material, you use pumps to distribute liquid across the packing material,
把接触器用包装材料装满，用泵将液体分布至包材的各处，
and you can use fans, as you can see in the front, to bubble the air through the liquid.
你还可以用风扇，如图中的前方所示，让空气通过液体产生泡泡。
The CO2 in the air is separated by the liquid by reacting with the really strong-binding CO2 molecules in solution.
空气中的二氧化碳和液体分离，因为它会和溶液中结合力极强的二氧化碳分子发生作用。
And in order to capture a lot of CO2, you have to make this contactor deeper.
为了要采集很多二氧化碳，这个接触器必须要做得很深。
But there's an optimization, because the deeper you make that contactor,
但有个优化的点，因为接触器越深，
the more energy you're spending on bubbling all that air through.
你就要花更多能源来把空气打过去。
So air contactors for direct air capture have this unique characteristic design,
所以，直接采集空气的空气接触器在设计上有这项独特的特征，
where they have this huge surface area, but a relatively thin thickness.
有很大的表面积，厚度相对就很薄。
And now once you've captured the CO2, you have to be able to recycle that material that you used to capture it, over and over again.
一旦你采集到了二氧化碳，你就得要回收那些用来采集它的材料，一次又一次。
The scale of carbon capture is so enormous that the capture process must be sustainable, and you can't use a material just once.
碳采集工作的规模是很庞大的，采集过程必须要是永续的，材料不能只用一次就丢。
And so recycling the material requires an enormous amount of heat, because think about it:
而回收那些材料就需要很大量的热，因为，想想看：
CO2 is so dilute in the air, that material is binding it really strong,
在空气中，二氧化碳会被稀释，和它结合的材料非常强而有力，
and so you need a lot of heat in order to recycle the material.
因此会需要很大量的热才能回收那些材料。
And to recycle the material with that heat, what happens is that
如果用那样的热来将材料回收，会发生的结果是，
concentrated CO2 that you got from dilute CO2 in the air is now released, and you produce high-purity CO2.
从空气中稀释的二氧化碳所取得的浓缩二氧化碳现在被释出了，产生了高纯度的二氧化碳。
And that's really important, because high-purity CO2 is easier to liquify, easier to transport,
那很重要，因为高纯度的二氧化碳比较容易液化，比较容易运送，
whether it's in a pipeline or a truck, or even easier to use directly, say, as a fuel or a chemical.
不论是透过管线或是卡车都一样，更容易直接使用，比如用来当燃料或化学物质。
So I want to talk a little bit more about that energy.
所以，关于那能源，我想要再多谈一点。
The heat required to regenerate or recycle these materials absolutely dictates the energy and the subsequent cost of doing this.
重新产生或回收这些材料所需要的热会直接影响到能源和做这件事的后续成本。
So I ask a question: How much energy do you think it takes to remove a million tons of CO2 from the air in a given year?
所以我要问一个问题：你们认为要花多少能源，才能在一年内把空气中的100万吨二氧化碳除去？
The answer is: a power plant. It takes a power plant to capture CO2 directly from the air.
答案是：一座电厂的能量。需要用一座电厂才能直接采集空气中的二氧化碳。
Depending on which approach you choose, the power plant could be on the order of 300 to 500 megawatts.
看你选的方法是哪一种，用的可能是三到五百万瓦特的电厂。
And you have to be careful about what kind of power plant you choose.
要选哪一种电厂，也要十分谨慎。
If you choose coal, you end up emitting more CO2 than you capture.
如果选择燃煤电厂，最终排放的二氧化碳可能比采集到的还多。
Now let's talk about costs.
现在来谈谈成本。
An energy-intensive version of this technology could cost you as much as $1,000 a ton just to capture it. Let's translate that.
这种技术，如果用的是高能源的版本，每吨可能要花上1000美元，这只是采集的成本。让我把它转成白话。
If you were to take that very expensive CO2 and convert it to a liquid fuel, that comes out to 50 dollars a gallon.
如果你打算要把非常昂贵的二氧化碳转换成液态燃料，那么算起来会是每加仑50美元。
That's way too expensive; it's not feasible.
那实在太贵了，不可行。
So how could we bring these costs down? That's, in part, the work that I do.
我们要如何减低成本？我有部分工作在处理这个问题。
There's a company today, a commercial-scale company, that can do this as low as 600 dollars a ton.
现在有一家公司，商业规模的公司，可以将价格压到每吨600元。
There are several other companies that are developing technologies that can do this even cheaper than that.
还有好几家其他公司在开发技术，想要把价格压到更低。
I'm going to talk to you a little bit about a few of these different companies.
我要跟各位谈谈这当中的少数几家公司。
One is called Carbon Engineering. They're based out of Canada.
其一是碳工程。该公司位于加拿大。
They use a liquid-based approach for separation combined with burning super-abundant, cheap natural gas to supply the heat required.
他们用液态的方式来做分离，再搭配燃烧足够且便宜的天然气来供应必要的热。
They have a clever approach that allows them to co-capture the CO2 from the air and the CO2 that they generate from burning the natural gas.
他们有个很聪明的方法，可以同时采集空气中的二氧化碳以及燃烧天然气所产生的二氧化碳。
And so by doing this, they offset excess pollution and they reduce costs.
通过这么做，可以抵消掉额外的污染并减少成本。
Switzerland-based Climeworks and US-based Global Thermostat use a different approach. They use solid materials for capture.
瑞士的气候工程及美国的全球恒温公司，采用的是不同的方法。它们用的是固态的采集法。
Climeworks uses heat from the earth, or geothermal, or even excess steam from other industrial processes to cut down on pollution and costs.
气候工程公司用的是来自地球的热，或地热，或甚至是工业过程中过量的蒸汽，以减少污染以及成本。
Global Thermostat takes a different approach.
全球恒温公司用的方式不同。
They focus on the heat required and the speed in which it moves through the material
他们把焦点放在必要的热以及热通过材料的速度，
so that they're able to release and produce that CO2 at a really fast rate,
这么一来，就可以快速地释放和产生那些二氧化碳，
which allows them to have a more compact design and overall cheaper costs.
让他们的设计可以变得更小巧，整体的成本也比较便宜。
And there's more still. A synthetic forest has a significant advantage over a real forest: size.
还有更多其他的。和真实的森林比，合成的森林有一个显著的优势：大小。

This next image that I'm showing you is a map of the Amazon rainforest.
我接下来要给各位看的图是亚马逊雨林的地图。
The Amazon is capable of capturing 1.6 billion tons of CO2 each year.
亚马逊每年可以采集16亿吨的二氧化碳。
This is the equivalent of roughly 25 percent of our annual emissions in the US.
这大约等同于美国每年排放量的25%。
The land area required for a synthetic forest or a manufactured direct air capture plant to capture the same is 500 times smaller.
换成是合成森林或专门用来采集空气的电厂，若要采集相同份量的二氧化碳，所需要用的面积小了500倍。
In addition, for a synthetic forest, you don't have to build it on arable land,
此外，合成的森林并不需要建造在耕地上，
so there's no competition with farmland or food, and there's also no reason to have to cut down any real trees to do this.
不会和农地或食物产生竞争，也不需要砍伐任何真正的树木就可以做到。
I want to step back, and I want to bring up the concept of negative emissions again.
我想要先退一步，我想要再提一下负排放的概念。
Negative emissions require that the CO2 separated be permanently removed from the atmosphere forever,
负排放是要把分离出的二氧化碳永远从大气中除去，
which means putting it back underground, where it came from in the first place.
也就是把它放回到地底，因为它最初是从地底来的。
But let's face it, nobody gets paid to do that today -- at least not enough.
但要面对现实，现今没有人能靠做这种事赚钱--至少赚不了多少钱。
So the companies that are developing these technologies
所以，在开发这些技术的公司，
are actually interested in taking the CO2 and making something useful out of it, a marketable product.
其实是想要把二氧化碳拿来做成有用的东西，有市场的产品。
It could be liquid fuels, plastics or even synthetic gravel.
可能是液态燃料、塑料或者甚至是合成碎石。
And don't get me wrong -- these carbon markets are great. But I also don't want you to be disillusioned.
别误会我的意思--这些碳市场是很棒的。但我也不希望各位的幻想破灭。
These are not large enough to solve our climate crisis,
刚谈的这些都还不足以解决我们的气候危机，
and so what we need to do is we need to actually think about what it could take.
我们需要做的是要真正去思考要花什么代价。
One thing I'll absolutely say is positive about the carbon markets is that they allow for new capture plants to be built,
对于碳市场，有一个优点我一定会说，那就是，因为它们，新的采集厂得以建立起来，
and with every capture plant built, we learn more.
而每建立一座采集厂，我们就会学到更多。
And when we learn more, we have an opportunity to bring costs down.
当我们学到更多，我们就有机会把成本降低。
But we also need to be willing to invest as a global society.
但我们这个全球共同体也得要愿意去投资。
We could have all of the clever thinking and technology in the world,
我们或许有各种聪明的想法和技术，
but it's not going to be enough in order for this technology to have a significant impact on climate.
但那还不够让这项技术对于气候产生够显著的影响。
We really need regulation, we need subsidies, taxes on carbon.
我们很需要法规，我们需要补助，碳相关的税。
There are a few of us that would absolutely be willing to pay more, but what will be required
很少有人会愿意付更多，但需要做的是，
is for carbon-neutral, carbon-negative paths to be affordable for the majority of society in order to impact climate.
要让碳中和与负碳的途径便宜到社会上大部分人都能负担，这样才能对气候有所影响。
In addition to those kinds of investments, we also need investments in research and development.
除了那些投资之外，我们也需要在研究和开发上做投资。
So what might that look like? In 1966, the US invested about a half a percent of gross domestic product in the Apollo program.
所以，看起来会是什么样子？1966年，美国将大约一半的国内生产总值投资在阿波罗计划上。
It got people safely to the moon and back to the earth.
该计划让人类安全登陆月球并返回地球。
Half a percent of GDP today is about 100 billion dollars.
当年国内生产总值的一半，约等于现今的1000亿。
So knowing that direct air capture is one front in our fight against climate change,
已经知道直接采集空气是我们对抗气候变迁之战的前线，
imagine that we could invest 20 percent, 20 billion dollars.
想象一下，若我们能投资20%，即200亿元，会如何。
Further, let's imagine that we could get the costs down to a 100 dollars a ton.
此外，也想象一下，我们能把成本降低，降到每吨100元。
That's going to be hard, but it's part of what makes my job fun.
那会很困难，但这也是让我的工作很有趣的原因之一。
And so what does that look like, 20 billion dollars,100 dollars a ton?
所以，200 亿元，每吨100元，会是什么样子？
That requires us to build 200 synthetic forests, each capable of capturing a million tons of CO2 per year.
那会需要建造200座合成森林，每一座每年都能够采集100吨的二氧化碳。
That adds up to about five percent of US annual emissions.
加起来，总共约是美国每年排放量的5%。
It doesn't sound like much. Turns out, it's actually significant.
听起来不很多。结果发现，其实是很重大的。
If you look at the emissions associated with long-haul trucking and commercial aircraft, they add up to about five percent.
如果看看长程货车运输以及商业飞机相关的排放，它们加起来大约是5%。
Our dependence on liquid fuels makes these emissions really difficult to avoid.
我们对于液态燃料的依赖让这些排放非常难避免。
So this investment could absolutely be significant.
所以，这项投资绝对是重要的。
Now, what would it take in terms of land area to do this, 200 plants?
要花费多少土地面积才能做到200座采集厂？
It turns out that they would take up about half the land area of Vancouver.
结果算出来是大约温哥华土地面积的一半左右。
That's if they were fueled by natural gas. But remember the downside of natural gas -- it also emits CO2.
前提是要用天然气来当燃料。但别忘了，天然气也有不利的一面，它也会排放二氧化碳。
So if you use natural gas to do direct air capture, you only end up capturing about a third of what's intended,
所以，如果用天然气来直接做空气采集，最后只能采集到预期量的三分之一左右，
unless you have that clever approach of co-capture that Carbon Engineering does.
除非你有聪明的同时采集方法，就像炭工程公司用的方法。
And so if we had an alternative approach and used wind or solar to do this,
如果我们有替代的方法，用风力或太阳能来取代，
the land area would be about 15 times larger, looking at the state of New Jersey now.
土地面积会变成约15倍大，近似现在的新泽西。
One of the things that I think about in my work and my research is
我在工作和研究时会思考的其中一件事情，
optimizing and figuring out where we should put these plants and think about the local resources available
是要想出把这些采集厂放在哪里最好，并考虑可得的当地资源，
whether it's land, water, cheap and clean electricity
不论是土地、水资源、便宜且干净的电力，
because, for instance, you can use clean electricity to split water to produce hydrogen,
因为，比如，可以用干净的电力来做水分裂，产生氢，
which is an excellent, carbon-free replacement for natural gas, to supply the heat required.
氢是很好的天然气替代品，不会产生碳，用来产生需要的热。
But I want us to reflect a little bit again on negative emissions.
但我希望大家能再次反思负排放。
Negative emissions should not be considered a silver bullet,
负排放不该被视为神奇的解决方案，
but they may help us if we continue to stall at cutting down on CO2 pollution worldwide.
但如果我们在减少全球二氧化碳时一直遇到瓶颈，负排放也许可以帮助我们。
But that's also why we have to be careful.
但也因此，我们得要很小心。
This approach is so alluring that it can even be risky,
这种方法非常诱人，甚至可能有风险，
as some may cling onto it as some kind of total solution to our climate crisis.
因为有些人可能会太依重它，把它视为是气候危机的完全解决方案。
It may tempt people to continue to burn fossil fuels 24 hours a day, 365 days a year.
它可能会诱使大家继续燃烧化石燃料，一年365天，一天24小时不断地烧。
I argue that we should not see negative emissions as a replacement for stopping pollution,
我主张不要把负排放视为是阻止污染的替代品，
but rather, as an addition to an existing portfolio that includes everything,
而是在既有的方案组合外，再外加一个无所不包的方案，
from increased energy efficiency to low-energy carbon to improved farming
内容从增加能源效能，到低能源碳，到改善农业，
will all collectively get us on a path to net-zero emissions one day.
会一起让我们有朝一日能走上净碳排放为零的路途。
A little bit of self-reflection: my husband is an emergency physician.
一点点自我反思：我丈夫是急诊室医生。
And I find myself amazed by the lifesaving work that he and his colleagues do each and every day.
他和他的同事每天的工作就是拯救人命，我觉得很了不起。
Yet when I talk to them about my work on carbon capture, I find that they're equally amazed,
然而，当我和他们谈到我的碳采集工作时，他们也同样觉得很了不起，
and that's because combatting climate change by capturing carbon isn't just about saving a polar bear or a glacier.
那是因为用采集碳来对抗气候变迁并不只是要拯救北极熊或是冰河。
It's about saving human lives.
它也是在拯救人命。
A synthetic forest may not ever be as pretty as a real one,
合成森林可能没有真实森林那么漂亮，
but it could just enable us to preserve not only the Amazon, but all of the people that we love and cherish,
但有了它，我们就不只能保护亚马逊，还能保护所有我们爱与珍惜的人，
as well as all of our future generations and modern civilization. Thank you.
以及我们未来的世代和现代文明。谢谢。