Is Climate Change Slowing Down the Ocean? | Susan Lozier | TED

翻译人员: Alvin Lee 校对人员: Lening Xu

I'm going to start this morning

今天早上，我将向大家介绍

by telling you about a 12th century natural philosopher

一位 12 世纪的自然哲学家，

named Adelard of Bath.

他叫阿德拉德（Adelard）， 来自巴斯。

Adelard compiled a list of unanswered questions

阿德拉德在他漫长的生命即将结束时 整理了一系列未解的问题。

near the end of his long life.

Among the 76 questions in his treatise on nature

有他关于自然的论述中， 有 76 个问题

were those that interest an oceanographer like me:

引起了像我这样的海洋学家的兴趣：

Why are the waters of the sea salty?

为什么海水是咸的？

Whence comes the ebb and flow of the tide?

潮起潮落从何而来？

And why does the ocean not increase from the influx of the rivers?

为什么海洋没有因为 河流的涌入而越来越大？

Nine centuries later,

9 个世纪之后，

oceanographers are asking questions unfathomable to Adelard.

海洋学家们正在提出一些 阿德拉德难以理解的问题。

How will navigation routes change as sea and land ice continue to melt?

随着海陆冰川持续融化， 航道将如何改变？

How are marine ecosystems faring in these warming waters?

海洋生态系统如何适应变暖的海水？

And, will climate change cause the collapse

以及，气候变化是否会引起

of the ocean overturning circulation?

海洋翻转环流的崩溃？

If that last one puzzles you, let me explain.

如果最后一个让你困惑的话， 我来解释一下。

Ocean waters are constantly on the move.

海水是不停在流动的。

Many of the ocean waters are local,

许多海水是区域性的，

like the surface currents of the North Atlantic you see here.

就像你在这张图上看到的 北大西洋表层洋流。

But the ocean is also home to large currents

但是海洋中也存在大规模的洋流，

that travel from one ocean basin to the next,

它们从一个洋盆流动到另一个洋盆，

often thousands of kilometers away.

距离通常达到几千公里。

The largest of these is referred to as the “ocean overturning circulation.”

其中最大的洋流 就被称为“海洋翻转环流”。

This current originates at high latitudes.

这股洋流发源于高纬度地区。

In the winter,

在冬季，

when cold winds blow across the ocean,

凌烈的寒风吹过海洋，

warm surface waters are converted to cold waters.

温暖的表层海水变冷。

That's the orange arrow turning blue.

就是这些橙色的箭头变成蓝色。

These cold waters are now denser than the waters underneath,

这些冷水的密度比底层海水大，

and so they sink and then spread at depth to distant parts of the globe

于是它们下沉，

然后沿着蓝色的带子从深处扩散到全球。

following that ribbon of blue.

Eventually these waters upwell,

最终这些海水会上升，

meaning they return to the surface where they warm.

意味着它们会回到温暖的海洋表面。

And so now the blue ribbon turns back to orange,

于是现在蓝色的带子变回橙色，

and they return to where they started completing the ocean overturning.

海水回到它们出发的地方， 完成了海洋翻转环流。

Now, this ocean overturning redistributes heat on our planet.

这种海洋翻转环流 重新分配了地球的热量。

In partnership with the atmospheric circulation,

在大气环流的共同作用下，

这一流体运动保持了赤道和 两极间 30 摄氏度的温差。

this fluid movement maintains a 30-degree-Celsius difference

between the equator and the poles.

Without these fluid motions,

如果没有这一海洋运动，

that temperature difference would be 110 degrees Celsius

温差将达到 110 摄氏度，

and not just over the ocean,

不仅在海洋上如此，

inland as well.

内陆地区也如此。

Polar latitudes would be completely frozen,

极地将完全被冰封，

and the tropics, well the tropics would be even more sweltering.

热带地区将更加酷热难当。

But this overturning also impacts our climate

但这种翻转也影响了我们的气候，

because when those waters sink,

因为当这些海水下沉时，

they carry with them the carbon dioxide they've gained

它们会携带着 同大气交换而来的二氧化碳。

by exchange with the atmosphere.

And so as a result of this, as the decades have progressed,

由此带来的结果就是， 随着过去几十年的发展，

the amount of carbon taken up or fluxed into the ocean

随着大气中二氧化碳浓度的增加,

has been increasing

in tandem with the increasing concentrations of carbon dioxide

被吸收或流入海洋的碳量也一直在增加,

in the atmosphere.

In fact, the ocean now stores 30 percent of the carbon dioxide

事实上，目前海洋中存储着

人类自工业革命以来

released by humanity

since the start of the Industrial Revolution.

排放的二氧化碳总量的 30%。

Now, this does mean that the levels of carbon dioxide in the atmosphere

这的确意味着大气中的二氧化碳水平

are less than they would be otherwise, which is good news.

低于正常情况下的水平， 这是个好消息。

But that carbon uptake by the ocean increases ocean acidity,

但是海洋对碳的吸收 会增加海洋的酸度，

which is not good news for marine species that build skeletons and shells.

这对于依赖建造骨骼和贝壳 生存的海洋生物而言不是一个好消息。

And it is certainly not good news for marine ecosystems in general.

那它对整个海洋生态系统 当然也不是个好消息了。

Now, as our ocean continues to warm and as ice continues to melt,

如今，随着我们的海洋持续变暖， 冰川持续融化，

both of which cause surface waters to become less dense,

这两者都会引起表层海水密度下降，

we fully expect that at some point, in winter,

我们完全可以预见到， 到了某个节点，在冬季，

those surface waters will not get dense enough to sink.

表层海水密度将达不到下沉的标准。

And at that point, we expect the overturning to slow.

到那时，海洋翻转环流会变慢。

And if the overturning slows,

一旦它变慢，

well, there will be less carbon uptake by the ocean.

尽管海洋吸收的碳会减少。

But there will also be even more major disruptions to our climate

但同时，我们的气候和天气模式 也将受到更大的破坏。

and weather patterns; we can expect stronger hurricanes,

我们可以预见更强的飓风，

even more intense precipitation.

更加猛烈的降水。

Just about now, you might be wondering,

现在你可能在想，

how quickly might the overturning change?

翻转环流的变化有多快？

Well, for decades, oceanographers assumed that the overturning changed slowly

几十年来，海洋学家一直假设 翻转环流的变化很缓慢，

on the time scales of tens of thousands of years, in concert with the ice ages.

其时间尺度是以几万年计， 与地球冰期的周期变化相同。

But a study in the 1990s of ice sheets,

但20世纪90年代的一项 关于冰盖的研究，

which hold bubbles of air from past climates,

其容纳了过去气候的气泡，

well, that study suggested that the overturning could change quickly,

这项研究指出， 翻转环流的变化可能很快，

within decades, maybe even within years.

有可能数十年内，甚至几年内。

And with that, the possibility of an abrupt collapse

这样一来，人为造成地球变暖，

of the overturning circulation brought about by human-induced warming?

从而引起海洋翻转环流 突然崩溃的可能性也随之而来了？

Well, at that point it became a very real possibility.

这么说，这种可能性是非常高的。

Thankfully, advances in climate modeling

值得庆幸的是，气候建模的进步 使我们对这种风险有了更好的了解。

give us a much better idea today of that risk.

The black and gray lines that you see on this graph

这张图表上黑色和灰色的线条

are the model reconstructions of the past relatively steady overturning changes.

是模型重建的过去 相对稳定的翻转环流变化。

The lines of various colors show you the future projections

彩色的线条是基于不同的气候模型

of the overturning, based on different climate models

和不同的气候条件

and different climate scenarios.

对于未来翻转环流变化的预测。

I'm going to start with the good news.

我先从好消息说起。

And the good news is that the overturning is unlikely to collapse

好消息是，翻转环流的崩溃

before 2100.

在 2100 年前不会发生。

Now, before anybody breathes a sigh of relief,

在大家都长舒一口气前，

I will remind you that our children, our grandchildren, will likely see 2100.

我要提醒你们，我们的子孙后代 可能会看到 2100 年。

And really, none of us are out of the woods

而且说真的， 我们都没有完全摆脱危险，

because the overturning is likely to weaken over this century

因为海洋翻转环流在本世纪

by between 11 percent and 34 percent.

可能会减弱 11% 到 34%之间。

And that weakening is enough to cause the disruptions that I mentioned earlier.

这种减弱已经足够引发 我刚刚提到的严重破坏。

Now back to those various lines of color.

现在我们说回那些彩色的线条。

All future projections show a decline,

所有的预测都呈下降趋势，

but they differ in how fast and by how much that decline will be.

只是下降的速度和程度不同。

And this is exactly where observations come in,

这就是为什么我们要进行观测，

because the longer we measure, the better our predictions will be.

观测的时间越长， 我们的预测就会越准确。

If Adelard had started measuring nine centuries ago,

如果阿德拉德从 9 个世纪前就开始观测，

we would be way ahead of the game.

我们就会在这场竞赛中遥遥领先。

Unfortunately, we only started measuring in this century

不幸的是，我们的观测 仅仅开始于本世纪，

when we had the resources

因为这时我们才有资源

and, frankly, the motivation to do so.

有动力来做这件事。

One of those efforts is an international observing system

我们所做的努力之一 是一个国际观测系统，

in the subpolar North Atlantic.

位于北大西洋靠近北极的地方。

OSNAP stretches from the Labrador coast to one side of Greenland,

OSNAP（北大西洋近极地海洋翻转环流项目） 从拉布拉多海岸一直延伸到格陵兰岛的一侧，

and then again from the other side of Greenland,

然后又从格陵兰岛的另一侧开始，

all the way over to the Scottish coast.

一直到苏格兰海岸。

Those red ribbons depict the surface currents,

这些红色的线描绘的是表层洋流，

and those dark blue ribbons depict the deep currents

而这些深蓝色的线 描绘的是深层洋流。

of the ocean overturning circulation.

Every black vertical line you see is the mooring that stretches

你看到的每一条 黑色的垂直线都是锚固装置，

从海面延伸到海底，

from the sea surface to the sea floor,

upon which instruments, shown as red dots,

上面那些红色的点代表仪器，

those instruments are on those moorings, and they're measuring the ocean currents,

仪器安装在锚固装置上，

测量洋流，温度和盐度。

the temperature and the salinity.

Every other summer since 2014,

从 2014 年开始， 每隔一年的夏天，

research vessels like this one have traced the OSNAP line,

这样的研究船都会沿着 OSNAP 线航行，

deploying instruments and taking measurements.

安放仪器和进行测量。

Dozens of oceanographers from many different countries

数十位来自不同国家的海洋学家

have been on these cruises.

参与了这些航行。

Here's a former student of mine off the coast of Greenland,

这是我以前的一位学生， 在格陵兰岛近海，

bringing in a rosette of bottles that have captured water samples

回收采集了深海海水样本的采水器。

in the deep ocean.

OSNAP also allows us to use new technology,

OSNAP 还允许我们使用新技术，

like this autonomous glider that, once deployed,

就像这个自动驾驶的滑翔机，

一经部署， 它就会按照预先设置的路线，

will set off on a programmed course,

taking measurements at depth.

在深海进行测量。

Every now and again,

每隔一段时间，

this glider will pop to the surface and relay its information

这个滑翔机就会跳出海面， 把所获信息

to a passing satellite.

上传到经过的卫星。

You could be sitting in a cafe, enjoying your latte,

而你就可以坐在咖啡厅 享受一杯拿铁，

all the while downloading data from this glider,

等待滑翔机数据下载，

which, for a seasick-prone oceanographer like me, is a godsend.

对于我这样晕船的海洋学家来说， 简直就是上帝赐福。

(Laughter)

（笑声）

However, it is true

当然，话说回来，

that conditions on these cruises are sometimes challenging.

这样的航行的确条件艰苦。

But I must admit that the views are almost always worth it.

但我必须承认， 一路上的风景绝对值得。

Now, you can tell from a glance

现在，你们看一眼就知道，

that our OSNAP data to date

从 OSNAP 的数据和数据之间无法判断

do not tell us whether the overturning in this part of the ocean

在这部分海域的海洋翻转环流

is currently increasing or decreasing.

目前是增强还是减弱的。

And the reason for that is the same reason

而其中的原因，跟另一件事相同，

that you cannot tell what the stock market will do in a year

就像你无法通过 只看道琼斯工业指数一周的变化，

by looking at the Dow Jones Industrial Index for a week.

来判断未来一年的 股票市场走势一样。

There is noise in the market, and there is noise in the ocean.

股票市场有噪音，海洋里也有。

But just as we have confidence that stocks are a good bet in the long run,

但就像我们确信， 股票从长远来看是好的投资，

we have confidence that in the long run,

我们也确信，从长远来看，

the overturning will decline if our climate continues to warm.

海洋翻转环流 会随着气候变暖而减弱。

And with that confidence, we know that it's not enough for us to study

以此为基础， 我们明白仅仅孤立地研究

the overturning in isolation.

海洋翻转环流是不够的。

We need to understand how the overturning is impacting

我们需要理解海洋翻转环流 和海洋中发生的其他一切

and being impacted by everything else going on in the ocean.

是如何相互影响的。

I just told you, the ocean is noisy.

我刚刚说了，海洋里充满噪音。

Well, the ocean is also connected.

除此之外，海洋还是紧密联系的。

What's happening in one part of the ocean

这片海洋中发生的事情

affects what's going on in another part.

会影响到另一片海洋。

And so to understand and to improve our estimates of the overturning,

因此要理解和更好地评估 海洋翻转环流，

the warming, the freshening, the acidification,

海水变暖、变淡、酸化，

we need to measure globally.

我们需要从全球范围内进行测量。

And we are.

我们也是这么做的。

This NOAA buoy is out there,

这是美国国家海洋和气候管理局 放置的浮标，

measuring the exchange of carbon between the ocean and the atmosphere.

用来测量海洋和大气的碳交换。

This one buoy is but a small part of a vast global measurement system

这个浮标是庞大的全球 测量系统的一小部分，

that looks like this.

这个系统看起来是这样的。

Every line or dot you see on this map is where there is a ship,

这张地图上的每一条线或者一个点， 代表一艘船，

a mooring or buoy out in the ocean, taking measurements.

一个锚固装置，或者一个浮标， 它们漂浮在海上进行测量。

This multinational effort is the backbone of 21-century oceanography.

这种跨国合作的努力 是 21 世纪海洋学的支柱。

But we can do all those measurements of many things in many places.

我们可以在世界各地 进行各种测量，采取各种行动。

But to stem the warming, the freshening,

但是要阻止海洋变暖、变淡、酸化，

the acidification, the sea level rise

阻止海平面上升，

and to reduce the very real risk of an overturning slowdown or shutdown,

降低海洋翻转环流 变慢或者停止的真实风险，

there's one solution.

却只有一个方法。

We must work collectively

我们需要通力合作

to reduce the carbon dioxide in our atmosphere.

来减少大气中的二氧化碳。

Adelard did not have everything figured out in the 12th century,

艾德拉德在 12 世纪 有很多问题没解决，

and we certainly don't here in the 21st.

而 21 世纪的我们当然也一样。

Answers to Adelard's questions were centuries in the making.

阿德拉德的问题， 我们花了几个世纪才找到答案。

But to figure everything out on our end,

但是要解决我们的问题，

we don't have nine centuries.

我们没有 9 个世纪。

We don't have nine decades.

我们没有 90 年。

We probably have about nine years to get it right.

我们也许只有 9 年的时间 来解决问题。

And to get it right,

要解决问题，

it's just like everyone says,

就像俗话说的，

we need all hands on deck.

我们需要所有人齐心协力。

Thank you.

谢谢大家。

(Applause)

（掌声）