曾经存在过这样一个世界 Once there was a world
它与我们的世界区别不大 not so very different from our own.
偶尔会有自然灾害 There were occasional natural catastrophes,
大规模的火山喷发 massive volcanic eruptions and,
时不时还会有小行星造访 every once in a while, an asteroid would come barreling out of the blue
造成些许破坏 to do some damage.
但在最初的约十亿年里 But for the first billion years or so,
它似乎如同天堂一般 it would've seemed like a paradise.
这是我们设想的 This is what we think the planet Venus
太阳系早期时金星的模样 might have looked like when our Solar System was young.
后来一切就开始急转直下 Then things started to go horribly wrong.
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翻译 飞驰宇宙的杏仁斯嘉丽
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时间轴 蛋黄勺子
后期 吉吉
总监 OBAFGKM
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宇宙
时空之旅
金星 The planet Venus,
也许曾经如天堂一般 which once may have seemed like a heaven,
如今却成了地狱 turned into a kind of hell.
这两者间的平衡十分脆弱 The difference between the two can be a delicate balance,
脆弱得超乎你的想象 far more delicate than you might imagine.
一旦平衡被打破 便万劫不复 Once things began to unravel, there was no way back.
这就是金星 离我们最近的行星邻居 This is what Venus, our nearest planetary neighbor,
如今的模样 looks like today.
金星上的海洋早已不复存在 Venus's oceans are long gone.
其表面比滚烫的烤炉还要热 The surface is hotter than a broiling oven,
热得足以熔化铅 hot enough to melt lead.
[铅的熔点为327.502°C]
为什么 你可能会认为 Why? You might think it's because
这是因为金星比地球距离太阳近30% Venus is 30% closer to the Sun than the Earth is,
但这并非根本的原因 but that's not the reason.
金星完全被硫酸云包围着 Venus is completely covered by clouds of sulfuric acid
这种云使阳光几乎照不到金星表面 that keep almost all the sunlight from reaching the surface.
这理应使金星比地球寒冷得多 That ought to make Venus much colder than the Earth.
那为什么金星如此灼热呢 So why is Venus scorching hot?
这是因为一小部分阳光 It's because the small amount of sunlight
穿过云层 到达金星表面以后 that trickles in through the clouds to reach the surface
不能被反射回宇宙空间中 can't get back out again.
这股能量 The flow of energy
被浓密的二氧化碳大气阻隔 is blocked by a dense atmosphere of carbon dioxide.
二氧化碳气体 简写为CO2 That carbon dioxide gas-- or CO2 for short--
就像令人窒息的毯子一样 阻止热量流失 acts like a smothering blanket to keep the heat in.
没人在金星上烧煤 No one is burning coal
或者驾驶耗油量大的车 or driving big gas-guzzlers on Venus.
自然完全能摧毁环境 Nature can destroy an environment
而不用智慧生命的帮忙 without any help from intelligent life.
失控的温室效应统治了整个金星 Venus is in the grip of a runaway greenhouse effect.
为什么我们像在一个碗里 Why does it look like we're inside a bowl?
这是因为巨大的大气压 It's due to the intense atmospheric pressure.
这是金星13号的残骸 That's the wreck of Venera 13.
在1982年 In 1982,
前苏联科学家和工程师们 the scientists and engineers of what was then the Soviet Union
成功使这个飞行器在金星表面着陆 successfully landed this spacecraft on Venus.
他们设法使它保持冷却状态 They managed to keep it refrigerated
长达两个多小时 for over two hours,
这样它就能拍下它周围的状况 so it could photograph its surroundings...
并且将图片传输回地球 and transmit the images back to Earth
之后它装载的电子元件就过热烧毁了 before the onboard electronics were fried.
金星和地球诞生初期 拥有大致相同的碳含量 Venus and Earth started out with about the same amount of carbon,
但这两个世界向两个 but the two worlds were propelled
截然不同的方向发展 along radically different paths,
碳在两者历史中都具有决定性的地位 and carbon was the decisive element in both stories.
在金星上 碳几乎都是以气态 On Venus, it's almost all in the form of gas--
即二氧化碳的形式存在于大气中 carbon dioxide-- in the atmosphere.
地球上大部分的碳都已在坚固的保险箱 Most of the carbon on Earth has been stored for eons
碳酸盐岩中储存了亿万年之久 in solid vaults of carbonate rock,
就像这里 碳酸盐岩 like this one, part of a chain that forms
是构成英吉利海峡边著名的多佛白崖 the celebrated White Cliffs of Dover,
关键的一环 right on the English Channel.
是何方神圣造就了这般世界奇观 What titan built this wonder of the world?
是一种仅相当于针头千分之一的生物 A creature a thousand times smaller than a pinhead.
数以万亿计的 Trillions of them.
单胞藻 One-celled algae.
火山喷发将二氧化碳送入大气中 Volcanoes supply carbon dioxide to the atmosphere,
海洋缓慢吸收二氧化碳 and the oceans slowly absorb it.
这种机制运行了数百万年 Working over the course of millions of years,
这些微小的海藻捕获二氧化碳 the microscopic algae harvested the carbon dioxide
并把它变成这种小小的壳 and turned it into these tiny shells.
它们在洋底积累成厚厚的白垩沉淀 They accumulated in thick deposits of chalk,
或者说石灰岩 or limestone, on the ocean floor.
之后 活跃的地球将海床抬升 Later, the restless Earth pushed up the seafloor
雕刻出这样魁伟的悬崖峭壁 and carved out these massive cliffs.
其他海洋生物 Other marine creatures
吸收二氧化碳 建造了规模庞大的珊瑚礁 took in carbon dioxide to build enormous coral reefs.
海洋将溶解的二氧化碳转化成石灰岩 And the oceans converted dissolved CO2 into limestone
甚至无需生命体的帮助 even without any help from life.
最终 只有极少的碳以气态的形式 As a result, only a trace amount was left as a gas
留在地球的大气中 in Earth's atmosphere.
含量不到大气的万分之三 Not even three-hundredths of one percent.
想想看 大气中一万个分子里 Think of it-- fewer than three molecules
二氧化碳不超过三个 out of every ten thousand.
就是这些造成了 And yet, it makes the critical difference
贫瘠的荒地和生命的花园之间的天壤之别 between a barren wasteland and a garden of life on Earth.
如果一点二氧化碳都没有 With no CO2 at all,
地球将非常寒冷 the Earth would be frozen.
如果二氧化碳的量翻一倍 And with twice as many,
一万个分子中也只有六个是二氧化碳 we're still talking about only six molecules out of ten thousand.
环境就会非常炎热 Things would get uncomfortably hot
并且会引发一些严重的问题 and cause us some serious problems...
但也绝不会像金星那么热 but never as hot as Venus; not even close.
这颗行星的海洋早在数十亿年前 That planet lost its ocean to space
就已消散在太空中 billions of years ago.
没有海洋 它就无法从大气中 Without an ocean, it had no way to capture CO2
捕获二氧化碳 也无法将它贮藏为矿物质 from the atmosphere and store it as a mineral.
火山喷发出的二氧化碳 The CO2 from erupting volcanoes
就这样不断积累 just continued to build up.
今天 金星的大气层要比地球浓密90倍 Today, that atmosphere is 90 times heavier than ours.
几乎全部由吸热的二氧化碳组成 Almost all of it is heat-trapping carbon dioxide.
这就是金星有如地狱火海一般酷热 That's why Venus is such a ferocious inferno
以致生命无法存在 so hostile to life.
地球则恰恰相反 The Earth, in stunning contrast,
它是有生命的 is alive.
它会呼吸 It breathes...
但非常缓慢 but very slowly.
一呼一吸需要一整年 A single breath takes a whole year.
森林居住着地球上大部分的生命 The forests contain most of Earth's life,
而大部分森林位于北半球 and most forests are in the Northern Hemisphere.
当北半球春天来临时 When spring comes to the north,
森林从空气中吸收二氧化碳 the forests inhale carbon dioxide from the air
然后生长 大地春回 绿意盎然 and grow, turning the land green.
大气中的二氧化碳含量下降 The amount of CO2 in the atmosphere goes down.
秋天来临 植物落叶 叶子枯萎 When fall comes and the plants drop their leaves, they decay,
将二氧化碳释放回大气中 exhaling the carbon dioxide back into the atmosphere.
在南半球情况也一样 The same thing happens in the Southern Hemisphere
只是时间相反 at the opposite time of the year.
但南半球大部分是海洋 But the Southern Hemisphere is mostly ocean.
因此 是北半球的森林 So it's the forests of the north
左右了全球每年二氧化碳含量的变化 that control the annual changes in the global CO2.
地球已经像这样呼吸了 The Earth has been breathing like this
数千万年 for tens of millions of years.
但直至1958年才有人注意到这一点 But nobody noticed until 1958,
一位名叫查尔斯·戴维·基林的海洋学家 when an oceanographer named Charles David Keeling
设计了一种精准测量 devised a way to accurately measure
大气中二氧化碳含量的方法 the amount of carbon dioxide in the atmosphere.
基林发现了地球不易察觉的呼吸 Keeling discovered the Earth's exquisite respiration.
但他也发现了一个令人震惊的事实 But he also discovered something shocking--
有一个数字以人类历史上前所未有的速度增长 a rapid rise, unprecedented in human history,
那就是二氧化碳的总含量 in the overall level of CO2,
至今这个趋势仍在继续 one that has continued ever since.
二氧化碳含量已经远远超过了 It's a striking departure from the CO2 levels that prevailed
农业和文明兴起阶段的水平 during the rise of agriculture and civilization.
实际上 地球三百万年以来 In fact, the Earth has seen nothing like it
从未有过这样的经历 for three million years.
我们为何能如此肯定 How can we be so sure?
证据就蕴含在水中 The evidence is written in water.
地球一直用过往年份降下的雪 The Earth keeps a detailed diary
保存着详尽的记录 written in the snows of yesteryear.
气候学家从格陵兰和南极洲的 Climate scientists have drilled ice cores
冰川深处钻出冰芯 from the depths of glaciers in Greenland and Antarctica.
远古空气被困在冰层中 The ice layers have ancient air trapped inside them.
我们能读到地球大气的完整记录 We can read the unbroken record of Earth's atmosphere
一直可追溯至80万年前 that extends back over the last 800,000 years.
在过去的所有时间里 In all that time,
大气中的二氧化碳含量从未超过 the amount of carbon dioxide in the air never rose
百万分之三 above three-hundredths of one percent.
直到二十世纪才有了变化 That is, until the turn of the 20th century.
从那以后 它就开始稳定而迅速地增长 And it's been going up steadily and rapidly ever since.
现在这个数字比工业革命之前 It's now more than 40% higher
高出了40% than before the Industrial Revolution.
通过燃烧煤 石油和天然气 By burning coal, oil and gas,
人类文明在不断排放二氧化碳 our civilization is exhaling carbon dioxide
排放的速度远超过了地球能吸收的速度 much faster than Earth can absorb it.
二氧化碳就在大气中不断累积 So CO2 is building up in the atmosphere.
整个星球都在升温 The planet is heating up.
所有发热的物体都在发出一种 Every warm object radiates a kind of light
我们用肉眼看不见的光线 we can't see with the naked eye--
红外线 thermal infrared light.
我们都在向外发出热辐射 即使身处黑暗 We all glow with invisible heat radiation, even in the dark.
这就是红外线下的地球 This is what the Earth looks like in the infrared.
你可以看见地球本身的热量 You're seeing the planet's own body heat.
太阳发出的光到达地球表面 Incoming light from the Sun hits the surface.
地球本身吸收了大部分能量 The Earth absorbs much of that energy,
使地球升温 which heats the planet up
也使地表发出红外线 and makes the surface glow in infrared light.
但大气中的二氧化碳 But the carbon dioxide in the atmosphere
吸收了散发出的大部分热量 absorbs most of that outgoing heat radiation,
将大部分热量传送回地表 sending much of it right back to the surface.
这就使地球更加温暖 This makes the planet even warmer.
这就是所谓的温室效应 That's all there is to the greenhouse effect.
它的基本原理 It's basic physics,
就是使能量留存下来 just bookkeeping of the energy flow.
这一点是毫无争议的 There's nothing controversial about it.
如果大气中没有任何二氧化碳 If we didn't have any carbon dioxide in our atmosphere,
地球就会变成一个大雪球 the Earth would just be a great big snowball,
我们人类也不会存在 and we wouldn't be here.
所以适度的温室效应是件好事 So, a little greenhouse effect is a good thing.
但严重的温室效应会使气候失常 But a big one can destabilize the climate
毁掉我们的生活 and wreck our way of life.
好吧 但我们怎么知道自己就是问题所在 All right... but how do we know that we're the problem?
也许二氧化碳含量升高是地球本身造成的 Maybe the Earth itself is causing the rise in CO2.
也许这与我们燃烧煤和石油毫无关系 Maybe it has nothing to do with the coal and oil we burn.
也许是因为那些该死的火山 Maybe it's those damn volcanoes.
每过几年 西西里岛的埃特纳火山就会喷发 Every few years, Mount Etna, in Sicily, blows its stack.
每次大型喷发都会把百万吨二氧化碳 Each big eruption sends millions of tons of CO2
排放到大气中 into the atmosphere.
现在 如果把它与 Now, combine that with the output
地球上所有其他的火山活动都加在一起 of all the other volcanic activity on the planet.
我们就按估计值的最大值算 Let's take the largest scientific estimate--
每年火山大概会把五亿吨二氧化碳 about 500 million tons of volcanic CO2
排放到大气中 entering the atmosphere ever year.
听起来可真不少 是不是 Sounds like a lot, right?
但这几乎还达不到人类每年产生的百分之二 But that's not even two percent of the 30 billion tons of CO2
也就是每年三百亿吨二氧化碳 that our civilization is cranking out every year.
而且 有趣的是 And, funny thing,
测量出的大气中二氧化碳的增量 the measured increase in CO2 in the atmosphere
与已知的燃烧煤 石油和天然气排放量 tallies with the known amount we're dumping there
刚好吻合 by burning coal, oil and gas.
火山喷发排放的二氧化碳有一个明显特征 Volcanic CO2 has a distinct signature--
它比燃烧化石燃料排放的 it's slightly heavier than the kind produced
要稍重一些 by burning fossil fuels.
当我们在原子层面检测时 We can tell the difference between the two
我们可以分辨出两者的区别 when we examine them at the atomic level.
很明显 大气中增长的二氧化碳 It's clear that the increased CO2 in the air
并非来自火山 is not from volcanoes.
还有 人们观测到的地球变暖程度 What's more, the observed warming is as much as predicted
与二氧化碳的增幅几乎同步 from the measured increase in carbon dioxide.
这二者紧密相关 It's a pretty tight case.
证据充足 我们无法开脱 Our fingerprints are all over this one.
每年排放三百亿吨二氧化碳是什么概念 How much is 30 billion tons of CO2 per year?
如果你把它压成固体 If you compressed it into solid form,
它的体积将与 it would occupy about the same volume
多佛白崖差不多 as the White Cliffs of Dover.
而且我们每年都向大气中排放这么多二氧化碳 And we're adding that much CO2 to the air every year,
无休止地 年复一年地 relentlessly, year after year.
不幸的是 人类文明产生的 Unlucky for us, the main waste product
主要废弃物不是其他的什么物质 of our civilization is not just any substance.
这种气体恰恰是年复一年 It happens to be the chief climate-regulating gas
保持地球气候稳定的主要成分 of our global thermostat, year in, year out.
二氧化碳是一种看不见的气体 真是糟糕 Too bad CO2 is an invisible gas.
如果我们能看见它... Maybe if we could see it...
如果我们的眼睛能感受到二氧化碳 If our eyes were sensitive to CO2--
也许宇宙中真的存在这种生物 and perhaps there are such beings in the cosmos--
如果我们看见所有的二氧化碳 if we could see all that carbon dioxide,
那样我们就不会再否认 then we would overcome the denial
而是理解我们对于大气的严重影响 and grasp the magnitude of our impact on the atmosphere.
但全球变暖的证据 But the evidence that the world is getting warmer
就在我们身边 is all around us.
首先 我们来检查一下温度计 For starters, let's just check the thermometers.
全世界的气象站 Weather stations around the world
自十九世纪八十年代起 have been keeping reliable temperature records
就开始记录可靠的温度数据 since the 1880s,
美国航天局用这些数据 and NASA has used the data to compile a map
编制了一份不同年份中 tracking the average temperatures
地球平均气温的地图 around the world through time.
黄色表示 对于这一地区 Yellow means warmer temperatures
气温高于十九世纪八十年代水平 than the average, for any region in the 1880s.
橙色表示炎热 Orange means hot.
红色表示更热 And red means hotter.
世界比它在十九世纪时更暖了 The world is warmer than it was in the 19th century.
当年 在全球最伟大的世界博览会上 Back then, at the greatest fair the world has ever seen,
一个被遗忘的天才找到了问题的解决方法 a forgotten genius demonstrated the solution to this problem.
跟我来 Come with me.
曾经存在过这样一个世界 Once there was a world
既不太炎热也不太寒冷 that was not too hot and not too cold.
气温适中 It was just right.
接下来 上面繁衍的生命 Then there came a time when the life it sustained
开始注意到可爱的地球起了变化 began to notice our lovely planet was changing.
这并不意味着我们未曾预见到它的出现 And it's not as if we didn't see it coming.
早在1896年 As far back as 1896,
瑞典科学家斯凡特·阿伦尼斯 the Swedish scientist Svante Arrhenius
《空气中的碳酸将影响地表温度》
计算出如果大气中二氧化碳的量翻倍 calculated that doubling the amount of CO2 in the atmosphere
大气的作用就好像温室的玻璃
北极的冰就会融化 would melt the Arctic ice.
在二十世纪三十年代 In the 1930s,
美国物理学家E. O. 赫尔伯特 the American physicist E. O. Hulburt,
在海军实验室里 at the Naval Research Laboratory,
证实了这一结果 confirmed that result.
二氧化碳使地球升温
截至到那时 这些都仍然只是理论 So far, it was still just theoretical.
但随后 英国工程师盖伊·卡伦德 But then, the English engineer Guy Callendar
《论人类活动产生的二氧化碳及其对气温的影响》
搜集整理了 assembled the evidence to show
二氧化碳和全球平均气温 that both the CO2 and the average global temperature
确实都在上升的证据 were actually increasing.
即使现在 人们也可能通过文明排放的废物 Even now, man may be unwittingly changing the world's climate
弗兰克·百特博士 1958《天空之上:挣脱束缚的神》
无意间改变了全球气候 through the waste products of his civilization.
人类每年通过工厂和 Due to our release, through factories
汽车排放大量废气 and automobiles every year, of more than
含有超过六十亿吨二氧化碳 six billion tons of carbon dioxide,
这有助于大气从阳光中吸热 which helps air absorb heat from the Sun,
我们的大气似乎越来越暖 our atmosphere seems to be getting warmer.
这是坏事吗 This is bad?
计算表明 如果地球的温度 Well, it's been calculated, a few degrees rise
升高几度 in the Earth's temperature
会使两极冰盖融化 would melt the polar ice caps.
1960年 卡尔·萨根的博士论文中 In 1960, Carl Sagan's PhD thesis
首次写到 included the first calculation
金星上失控的温室效应的计算 of the runaway greenhouse effect on Venus.
这是他毕生兴趣的一部分 This was part of a career-long interest
长期致力于研究行星大气 也包括地球大气 in the atmospheres of the planets, including our own.
在1980年版《宇宙》中 In the original Cosmos series, in 1980,
卡尔·萨根提出警告 Carl Sagan warned...
我们正在排放大量二氧化碳 We are releasing vast quantities of carbon dioxide,
加剧了温室效应 increasing the greenhouse effect.
用不了多久 It may not take much
地球气候就会失稳 to destabilize the Earth's climate,
这会把这个天堂 我们在宇宙中的唯一家园 to convert this heaven, our only home in the cosmos,
变为地狱 into a kind of hell.
卡尔说完这些话之后 Since Carl spoke those words,
我们还在继续加重大气的负担 we've burdened the atmosphere of our world with an additional
又排放了四千亿吨二氧化碳 400 billion tons of carbon dioxide.
如果我们不改变生产方式 If we don't change our ways,
我们的子孙将会面对一个什么样的地球 what will the planet be like in our children's future?
根据科研结果 Based on scientific projections,
如果我们保持现有的经济模式不变 if we just keep on doing business as usual,
我们子孙的未来不容乐观 our kids are in for a rough ride.
致命的热浪 空前的干旱 Killer heat waves, record droughts,
海平面升高 大量物种灭绝 rising sea levels, mass extinction of species.
从祖先那里 我们继承了一个富饶的世界 We inherited a bountiful world
它因相对温和的气候而存在 made possible by a relatively stable climate.
农业和文明繁荣发展 Agriculture and civilization flourished
延续数千年 for thousands of years.
但是现在 我们的大意和贪婪 And now, our carelessness and greed
将这一切置于险境 put all of that at risk.
好 如果我们的科学家是如此出色 Okay, so if we scientists are so good
能作出这些可怕的关于气候的长远预测 at making these dire, long-term predictions about the climate,
那为什么预测天气就这么差劲呢 how come we're so lousy about predicting the weather?
再说了 今年我们镇冬天特别寒冷 Besides, this year, we had a colder winter in my town.
我们这些科学家知不知道 For all us scientists know,
全球可能正在变冷 we could be in for global cooling.
这就是天气与气候的差别 Here's the difference between weather and climate...
天气是短期内的大气状态变化 Weather is what the atmosphere does in the short term--
每小时的 每天的 hour to hour, day to day.
天气是复杂多变的 也就意味着 Weather is chaotic, which means that even
即使是微小的干扰也会引起大规模的变化 a microscopic disturbance can lead to large-scale changes.
这就是为什么十天天气预报几乎没用 That's why those ten-day weather forecasts are useless.
在巴厘岛上有只蝴蝶扇动翅膀 六周后 A butterfly flaps its wings in Bali, and six weeks later,
坏天气就毁掉了你在缅因州的户外婚礼 your outdoor wedding in Maine is ruined.
气候是天气长期的平均状态 跨越多年 Climate is the long-term average of the weather, over a number of years.
它是由这个星球上能改变大气能量平衡的 It's shaped by global forces that alter the energy balance
力量决定的 比如日照的变化 in the atmosphere, such as changes in the Sun,
地轴倾角的变化 the tilt of the Earth's axis,
地球反射回太空的太阳光 the amount of sunlight the Earth reflects back to space
还有大气中温室气体的浓度 and the concentration of greenhouse gases in the air.
以上任意一个因素变化都可以影响气候 A change in any of them affects the climate
而且我们基本可以预测它们的变化方式 in ways that are broadly predictable.
我的这位朋友在左摇右摆地散步 My friend's meandering
好比是短期的波动 represents the short-term fluctuations--
也就是天气 that's weather.
人们几乎不可能预测 It's almost impossible to predict
他下一秒被什么东西所吸引 what'll attract his interest next,
但我们不难得知他前进的大体方向 but not hard to know what the range of his meandering will be,
因为我用皮带拴着他 because I'm holding him on a leash.
我们无法直接观测气候 We can't observe climate directly--
我们所见皆是天气 all we see is the weather--
但天气的平均值 经过几年的积累 but the average weather, over the course of years,
会体现出某种模式 reveals a pattern.
我就好比是这个长期趋势 I represent that long-term trend,
也就是气候 which is climate.
把注意力放在人上 别放在狗上 Keep your eye on the man, not the dog.
天气难以预测 就像我的这位朋友 Weather is hard to predict, like my friend here,
但气候是可以预知的 but climate is predictable.
在地球漫长的历史中 气候曾有过多次变迁 Climate has changed many times in the long history of the Earth
每一次都是某种全球性力量的结果 but always in response to a global force.
目前影响气候变化的最强的力量 The strongest force driving climate change right now
就是因燃烧化石燃料而不断增加的二氧化碳 is the increasing CO2 from the burning of fossil fuels,
这使大气保留住更多阳光的热量 which is trapping more heat from the Sun.
这些多余的能量必须有个去处 All that additional energy has to go somewhere.
其中一部分加热空气 Some of it warms the air.
但大多数都被海洋吸收 Most of it ends up in the oceans.
全世界的海洋都在变暖 All over the world, the oceans are getting warmer.
最明显的例子在北冰洋 It's most obvious in the Arctic Ocean
以及环绕北冰洋的陆地 and the lands that surround it.
就算某个人迹罕至的地方 Okay, so we're losing the summer sea ice
少了一块夏季海冰又如何 in a place where hardly anyone ever goes.
北极有没有冰关我什么事呢 What do I care if there's no ice around the North Pole?
冰是地球最亮的自然表面 Ice is the brightest natural surface on the Earth,
开阔的海域则是最暗的自然表面 and open ocean water is the darkest.
冰可以将阳光反射回太空 Ice reflects incoming sunlight back to space.
水则会吸收阳光 Water absorbs sunlight
并受热变暖 这会使更多冰融化 and gets warmer, which melts even more ice,
也就会露出更多海面 which exposes still more ocean surface
来吸收更多阳光 to absorb even more sunlight.
我们把这种现象称为正反馈循环 This is what we call a positive feedback loop.
这是能把二氧化碳引起的热效应放大的 It's one of many natural mechanisms that magnify
诸多自然机制中的一个 any warming caused by CO2 alone.
我们在阿拉斯加的德鲁角 We're at Drew Point, Alaska,
地处北冰洋的边缘 on the edge of the Arctic Ocean.
我出生时 When I was born,
这里的海岸线比现在多伸出约1.6千米 the shoreline was a mile farther out,
它过去曾以每年6米多的速度回缩 and it was breaking off at a rate of about 20 feet per year.
而现在... Now...
回缩的速度超过每年15米 it's being eaten away at about 50 feet per year.
北冰洋正在变暖 The Arctic Ocean is warming
而且是加速变暖 and at an increasing rate.
所以每年的无冰期延长了 So it's ice-free during more of the year.
有更多的海岸线 That leaves the shore here
因此暴露出来 更易被风暴侵蚀 more exposed to erosion from storms,
这也让另一种力量变得更强大 which are also getting more powerful,
气候变化带来的另一种影响 another effect of climate change.
阿拉斯加 西伯利亚 加拿大的北部 The northern reaches of Alaska, Siberia and Canada
大部分都被永久冻土所覆盖 are mostly permafrost,
地面冻结超过千年 ground that has been frozen year-round for millennia.
这里面含有很多有机质 It contains lots of organic matter,
包括千年以前的 old leaves and roots from plants
旧叶与树根 that grew thousands of years ago.
由于北冰洋地区的升温速度 Because the Arctic regions are warming faster
比地球上其他任何地区都快 than anywhere else on Earth,
永久冻土开始融化 the permafrost is thawing
冻土中的内容物开始腐烂 and its contents are rotting,
就像有人拔掉了冰箱的插头 just like when you unplug the freezer.
融化的冻土释放出二氧化碳 The thawing permafrost is releasing carbon dioxide
还有甲烷 这是一种更强的温室气体 and methane, an even more potent greenhouse gas,
也被排放到大气中 into the atmosphere.
这让地球变得更暖 This is making things even warmer,
这是正反馈循环的又一例明证 another example of a positive feedback mechanism.
地球上的永久冻土层中储存有大量的碳 The world's permafrost stores enough carbon
足以让大气中的二氧化碳再增加一倍 to more than double the CO2 in the atmosphere.
按照我们现在的速度 At the rate we're going,
到本世纪末 全球变暖就要释放出 global warming could release most of it
其中大部分的二氧化碳了 by the end of the century.
人类也许正在将气候推上不归路 We might be tipping the climate past a point of no return
让它走向不可预知的深渊 into an unpredictable slide.
好 既然大气 水体 Okay, the air, the water
还有陆地都在变暖 and the land are all getting warmer,
那么全球变暖真的在发生 so global warming is really happening.
但也许这不是人类的错 But maybe it's not our fault.
也许只是自然造成的 Maybe it's just nature.
也许是太阳造成的 Maybe it's the Sun.
不 不是太阳 No, it's not the Sun.
几十年来 我们一直在密切地观测太阳 We've been monitoring the Sun very closely for decades,
而太阳输出的能量一直都没变过 and the solar energy output hasn't changed.
还有 地球的夜晚比白天 What's more, the Earth is warming more at night
升温更快 than in daytime,
冬天比夏天升温更快 and more in winter than in summer.
这与我们对温室效应规律的认识相符 That's exactly what we expect from greenhouse warming,
但与太阳输出能量的增加所引起的后果 but the opposite of what increased solar output
正好相反 would cause.
一切都确凿无疑地表明 It's now clear beyond any reasonable doubt
人类正在改变气候 that we are changing the climate.
太阳不是问题所在 The Sun isn't the problem.
却是解决方法 But it is the solution,
我们很久之前就了解这一切了 and we've known this for a long time,
比你能想到的要早得多 much longer than you might think.
巴黎 1878年9月 Paris, September 1878.
还要过很多年埃菲尔铁塔才会开始建造 The Eiffel Tower won't be built for years to come.
世界博览会
来看看世界上 Witness one of the most glorious spectacles
最壮观非凡的景象吧 the world has ever seen.
自由女神像宏伟的头部 The magnificent head of the Statue of Liberty
刚刚竣工 has just been completed.
来自全世界各地的数千家展商 Thousands of exhibitors from around the planet
在巴黎的400多亩土地上 covered 66 acres of Paris
放满了他们的发明与商品 with their inventions and goods.
爱迪生还要在一年以后 Edison's first public demonstration of the lightbulb
才会首次向公众展示灯泡 will not take place for another year.
那时电气设备还没有出现 There's no such thing as electrical appliances.
人们还不会开开关 按按钮 People don't flick switches and press buttons.
这是一个靠手工 靠马拉的世界 It's a hand-cranked, horse-drawn world.
这就是我们要说到的那个人 That's the guy we came to see,
那个有奇怪胡子的人 the one with the crazy moustache.
他是个名叫奥古斯丁·穆肖的数学老师 He's a math teacher named Augustin Mouchot.
记住 这可是在1878年 Remember, it's 1878.
世界大多是由煤气灯点亮的 This is a world lit mostly by gaslight.
汽车还要过好多年才会被发明出来 The automobile is still years away.
但穆肖 用他的太阳能集热器 But Mouchot, here, is dazzling the crowd
震撼了围观的人们 with his solar power concentrator.
太阳是属于我们大家的 The Sun belongs to all of us!
即使它距我们有1.5亿千米 Even though it is 150 million kilometers away from us,
感受它的伟大力量吧 feel its awesome power!
我的发明能集中太阳的免费能量 My invention concentrates the free energy of the Sun
并将其转化为机械运动 and converts it into mechanical motion.
它能驱动任何一种机器 It can power any kind of machine.
它能发电 能驱动印刷机 It can produce electricity or run a printing press
能在炎炎夏日制冰 or make ice on a hot day.
就像这样 Et voilà
想想吧 Think of it,
阳光都可以变成冰 sunlight converted into ice.
看啊 朋友们 You see, my friends,
如果我们能利用丰富的太阳能 what wonders we can work
我们能创造出怎样的奇迹啊 if we harness the bounteous energy of the Sun.
世界上的煤终有一天会耗尽 The world will someday run out of coal,
但伟大的太阳会永远为我们所用 but the magnificent Sun will always be there for us.
穆肖获得了那届世界博览会的金奖 Mouchot took home the gold medal from the fair.
但煤的价格暴跌 But the price of coal tumbled,
价格太便宜以至于没人对太阳能感兴趣 becoming so cheap that there was no interest in solar energy.
此外 那时还没人能够理解 Besides, no one understood, back then,
燃烧化石燃料的真正代价是什么 what the true cost was of burning fossil fuel.
穆肖的研究资金被切断 Mouchot's research funding was cut off.
35年后 在20世纪初期 35 years later, in the early years of the 20th century,
一扇通往另一种可能未来的门打开了 another door opened to an alternative future.
这发生在埃及 在尼罗河的岸上 It happened in Egypt, on the banks of the Nile.
给未来的时间旅人提个醒... Memo to future time travelers...
这是介入历史阻止气候变化的 this would be an excellent entry point
极佳穿越点 for averting climate change.
埃及 1913年 Egypt, 1913.
这是来自费城的弗兰克·舒曼 That's Frank Shuman of Philadelphia.
他只上过三年学 He's only had three years of schooling,
但他的创造才华弥补了这一切 but his genius for innovation more than makes up for that.
还没到30岁 他就发明了安全玻璃 Before he was 30, Shuman had invented safety glass.
它广泛用于汽车和天窗上 拯救了无数生命 Its use in automobiles and skylights saved countless lives
这让他变得非常富有 and made him a very rich man,
富有到他可以追逐自己真正的梦想 rich enough to pursue his real passion,
太阳能 solar energy.
舒曼领导他的团队 设计并建造了 Shuman led the team that designed and built
一组太阳能聚光器 an array of solar energy concentrators.
它能驱动蒸汽机 It could power a steam engine.
舒曼希望 利用太阳能 Shuman is hoping to use the Sun's power
灌溉沙漠 to irrigate the desert
绿化沙漠 and turn it green.
舒曼的太阳能工厂的 The official inauguration
正式落成仪式是在1913年 of Shuman's solar power plant, in 1913,
这是个辉煌的成就 was a dazzling success.
他发明了一种实用的方法 He had invented a practical way to tap the Sun's energy
以工业规模来利用太阳能 on an industrial scale,
能让太阳能比煤还要便宜 making solar energy even cheaper than coal.
英国和德国政府 The British and German governments
均给舒曼提供了丰厚的资金 both offered Shuman generous funding
让他改进他的发明 to develop his invention.
这是热带地区一种理想的充足的 It was the ideal source of abundant power
能量来源 in tropical regions,
在这里进口煤的价格太高 where imported coal was prohibitively expensive.
但舒曼的梦想更高远 But Shuman was dreaming even bigger.
在给《科学美国人》的信中 In a letter to Scientific American,
他计算出 如果他的太阳能工厂 he calculated that his solar power plants,
能在撒哈拉沙漠那样的地方 if deployed in an area of the Sahara Desert
部署240千米见方的机器 only 150 miles on a side,
就能为全世界工业提供足够的能量 could supply as much power as consumed by all the industries of the world.
但这一切最终没有发生 But it was not to be.
液体化石燃料 石油的市场 The market for a liquid fossil fuel, petroleum,
因船运需求 was exploding for shipping,
家庭采暖 汽车和卡车而迅速扩大 home heating, and cars and trucks.
石油很丰富 比煤还要便宜 Oil was abundant, cheaper even than coal,
也更容易开采和加工 and much easier to get out of the ground and process.
需要一百个人干上一周才能把煤装满一艘船 It took 100 men a week to fuel a ship with coal,
但如果是装石油 一个人可以在 but with oil, one man could do the job
一天内做完 in a single day.
舒曼在沙漠中取得胜利一年后 A year after Shuman's triumph in the desert,
第一次世界大战爆发了 World War I broke out.
他的太阳能集热器被回收利用 做成武器 His solar collectors were recycled into weapons.
弗兰克·舒曼关于太阳能驱动文明的梦 Frank Shuman's dream of a solar-powered civilization
还要再等上一个世纪 would have to wait another century
才能重获新生 before it was reborn.
在世界上 还有另一种零排放的 There's another inexhaustible source of clean energy
清洁能源 for the world.
风本身就是由太阳能产生的 The winds themselves are solar powered,
因为太阳驱动着风和波浪 because our Star drives the winds and the waves.
不同于太阳能集热器 Unlike solar collectors,
风力发电场不需要占用多少土地 wind farms take up very little land,
如果建在近岸 就不用占一丁点土地 and none at all, if offshore,
那里的风最强 where the winds are strongest.
哪怕我们能利用这能量的百分之一 If we could tap even one percent of their power,
我们也能获得足够的能量来驱动文明社会 we'd have enough energy to run our civilization.
一小时内落在地球上的太阳能 And more solar energy falls on Earth in one hour
就已经超过了人类一整年的 than all the energy our civilization consumes
能源消耗 in an entire year.
如果我们能利用一点点 If we could harness a tiny fraction
可用的太阳能和风能 of the available solar and wind power,
我们的能源需求就永远都能得到满足 we could supply all our energy needs forever,
也不用再向大气中排放碳 and without adding any carbon to the atmosphere.
现在尚不为晚 It's not too late.
未来是值得我们为之奋斗的 There's a future worth fighting for.
我是如何知道的 How do I know?
我们每一个人都是自然选择的幸存者的后代 Every one of us comes from a long line of survivors.
人类最突出的特点就是适应力强 Our species is nothing if not adaptive.
就是因为我们的祖先意识到 It was only because our ancestors learned
要眼光长远 应时而动 to think long-term, and act accordingly,
我们才能存在于此 that we're here at all.
我们曾陷入绝境 We've had our backs to the wall before,
但我们都安然度过 勇攀新高峰 and we came through to scale new heights.
实际上 人类历史上的很多伟大的成就 In fact, the most mythic human accomplishments of all
都是在我们最黑暗的日子取得的 came out of our darkest hour.
曾经存在过这样一个世界 Once there was a world
六万枚核武器准备就绪 蓄势待发 rigged with 60,000 hair-triggered nuclear weapons.
这场较量的双方 The combatants were
是世界上最强大的两个国家 the two most powerful countries on Earth,
他们被紧紧地绑在了一起 and they were locked in a deadly embrace,
双方都宣称他们宁可看着 each vowing that they would rather see
这个世界玉石俱焚 everything we love destroyed
也不会屈服于另一方的意志 than submit to the will of the other.
当我三岁时 When I was three years old,
苏联引爆了有史以来 the largest man-made explosion of all time
威力最强的人造炸弹 was detonated by the Soviet Union.
核恐慌刚刚平息 却又有新的恐慌出现了 That terror has subsided, to be replaced by new fears.
全球最大的两千个城市 The danger that the 2,000 largest cities on Earth
在半天内化为废墟的危险 would be reduced to rubble in the space of an afternoon
已经不足为惧了 is no longer one of them.
美国和苏联之间的 The nuclear rivalry between the United States
核对抗 and the Soviet Union
产生出了另一个副产品 had another by-product.
阿波罗登月计划 The Apollo missions to the Moon were an extension
就是美苏间军备竞赛的产物 of the arms race that raged between them.
把人送入地球轨道 Sending people to orbit the Earth
或者送上月球 都需要大型的 可靠的 or go to the Moon requires big, reliable,
大推力的火箭 这与另一种技术一模一样 powerful rockets-- precisely the same technology
你需要这种技术搭载核弹头 you need to carry a nuclear warhead
飞过半个地球 halfway around the planet
去摧毁敌人的最大城市 to destroy your enemy's largest cities.
我相信 这个国家 I believe that this nation
一定会达成这个目标 should commit itself to achieving the goal,
在未来的十年里 使人登上月球 before this decade is out, of landing a man on the Moon
并让他安全返回地球 and returning him safely to the Earth.
肯尼迪总统1961年的演讲 President Kennedy's 1961 speech
让整个国家陷入兴奋之中 electrified the nation,
其中包括很多让人印象深刻的远大计划 and it contained much that was remarkably prophetic--
但在关于登月计划的内容中 but not a word about a scientific objective
对于科学目的只字未提 for going to the Moon.
没有对月球起源的探索 No questions about the Moon's origin
也没有把月球样本带回来分析的想法 or the hope of bringing back samples to analyze.
不 阿波罗计划本就是为了 No, the Apollo missions were conceived
展示超级大国的实力 as a demonstration of the superior power
和战略导弹的精确度 and precision of our strategic missiles.
但可笑的是 But a funny thing happened to us
在我们走向月球的途中 on our way to the Moon.
我们回望家园... We looked homeward...
发现了另一个世界 and discovered another world--
我们自己的世界 our own.
我们这些地球的居民第一次 For the first time, we inhabitants of Earth
有机会能退后一步 总览它的全貌 could step back and see it as it really is--
这是一个不可分割的世界 one world, indivisible,
在宇宙环境中显得有点渺小 and kind of small in the cosmic context.
不管我们集中大量人力物力的初衷是什么 Whatever the reason we first mustered the enormous resources
为什么把这些投入到阿波罗计划上 required for the Apollo program,
不管冷战时期我们是如何深陷民族主义的思潮 however mired it was in Cold War nationalism
以及对杀人武器的追求 and the instruments of death,
我们都必须要承认 地球的统一性 the inescapable recognition of the unity
以及脆弱性 and fragility of the Earth
是阿波罗计划切实可见的成果 is its clear and luminous dividend,
是阿波罗计划给予我们的意外之礼 the unexpected gift of Apollo.
一个在死亡竞赛中想出的计划 A project conceived in deadly competition
却让我们拥抱彼此 made us recognize our community.
是何方神圣造就了这般世界奇观 What titan built this wonder of the world?
菲律宾的伊富高人 It was the Ifugao people of the Philippines,
几乎完全靠他们的双手劳作 working with not much more than their hands.
约一万年之前 我们在世界各地的祖先 About 10,000 years ago, our ancestors all over the world
利用了另一种形式的气候变化 took advantage of another form of climate change,
在间冰期稍显温和的气候中 the gentler climate of the intermission in the ice age--
他们发明了农业 they invented agriculture.
他们放弃了无休止的 They gave up the ceaseless wandering,
流浪 捕猎和采集的生活方式 hunting and gathering that had been their way of life
这种方式曾延续了约一百万年 for a million years or so,
他们定居下来 生产食物 to settle down and produce food.
他们找到了一种方法 They found a way to harvest
与自然环境给祖先的供给相比 ten to a hundred times more solar energy
能收获十倍到百倍的太阳能 than the environment naturally provided for their ancestors.
全世界的人类都完成了 People all over the world made the difficult transition
从游牧文明到农业文明的艰难转变 from nomadic cultures to agricultural ones
使得太阳能的利用效率大大提高 that used solar energy more efficiently.
文明得以产生 It gave rise to civilization.
我们站在那些完成艰苦工作的人的肩膀上 We stand on the shoulders of those who did the hard work
他们为我们实现了最基础的转变 that such a fundamental transformation required.
现在...轮到我们了 Now... it's our turn.
曾经存在过这样一个世界... Once there was a world...
如果金星上曾经存在过生命 它也没有机会 If life ever existed on Venus, it would have had no chance
扭转这个世界的可怕命运 to avert the hellish destiny of this world.
这失控的温室效应无法阻挡 This runaway greenhouse effect was unstoppable.
曾经... Once...
存在过这样一个世界... there was a world...
我们的世界 ours.
这个世界就是现在 And that world is now.
没有什么科学技术的障碍 There are no scientific or technological obstacles
会阻止我们保护世界 to protecting our world
和这个世界所供养的宝贵生命 and the precious life that it supports.
这都要看 It all depends...
我们真正珍惜的是什么 on what we truly value...
以及我们能否付诸行动 and if we can summon the will to act.
但是有些人问 为什么选择月球 But why, some say, the Moon?
为什么选择登月作为我们的目标 Why choose this as our goal?
就像他们还会问 And they may well ask,
为什么我们要登上最高峰 why climb the highest mountain?
我们决定登月 We choose to go to the Moon...
我们决定登月 we choose to go to the Moon...
我们决定在下个十年中登月 we choose to go to the Moon in this decade
并且完成其他的事 and do the other things,
不是因为它们轻而易举 not because they are easy,
而是因为它们困难重重 but because they are hard.
出自肯尼迪1962年演讲《我们选择登月》