|
When a Killer ClimateCatastrophe Struck the World's Oceans
当一场致命的气候灾难袭击全球海洋时
Identifying a killer can be difficult when it seemslike every murder weapon imaginable has been used in the crime, and when thevictim is the entire planet. About 252 million years ago, a rich and wonderfulworld was annihilated in the worst mass extinction ever: the end-Permian, acatastrophe with no close competitor in Earth’s history. Volcanoes of a trulypreposterous scale erupted in Siberia over many thousands of years, loosing allmanner of chaos on the world. Rounding up, everything died.
当所有可以想象得到的致命武器似乎都被用于犯罪时，当受害者是整个星球时，识别杀手可能会很困难。大约2亿5千2百万年前，一个富饶而美好的世界在有史以来最严重的物种大灭绝中覆没了：它发生在二叠纪末期，是一场在地球历史上最为严重的大灾难。在西伯利亚，几千年的时间里发生了一场真正可以说是规模反常的火山爆发，给世界带来了各种各样的混乱。最后，一切都陷入了死寂当中。
[copy]Diagnosing the particular flavor of chaosresponsible for this mass death has proven elusive. The Siberian Traps, nowlong retired as a vast swath of basalt plateaus in the far northern reaches ofRussia, might have poisoned the world with mercury. Or maybe they destroyed theozone layer by incinerating huge underground layers of ancient evaporites. Orperhaps they acidified the planet with sulfur dioxide and carbon dioxide,stripping vegetation, killing corals worldwide, and altering the chemistry ofthe planet’s soil so that dirt would have tasted like vanilla. Or maybe theSiberian Traps wracked the planet with brief volcanic winters, or they poisonedthe planet with carbon dioxide itself, or the oceans became stagnant andpoisoned with toxic hydrogen sulfide. Maybe that’s what killed everything.
事实证明，造成这种大规模死亡的混乱的特殊味道是难以捉摸的。现在早已隐退成为俄罗斯最北部的一大片玄武岩高原的西伯利亚暗色岩可能曾经用汞毒害了全世界。或许，它们可能通过焚烧地下的巨大且古老的蒸发岩层来破坏臭氧层。或许，它们可能用二氧化硫和二氧化碳使地球酸化，剥离植被，杀死世界各地的珊瑚，改变地球土壤的化学成分，使泥土尝起来像是香草味。或许西伯利亚暗色岩用短暂的火山冬季摧毁了地球，或许它们用二氧化碳毒害了地球，或许海洋被有毒的硫化氢毒害而变得一片死寂。或许这就是万物被杀死的原因。
Or maybe the oceans became stratified andnutrient-starved, and phytoplankton suffered. Or perhaps it was a lack ofoxygen in the ocean that suffocated everything, or maybe it got just too damnhot. Some paleontologists have thrown up their hands and yielded to thisoverdetermination of kill mechanisms at the end-Permian, proposing an inelegantMurder on the Orient Express hypothesis of mass extinction that implicates theentire suite of killers. A new study, though, claims to pinpoint the primarykiller from this murderers’ row: Among the slew of Very Bad Things implicatedin the worst calamity the Earth has ever known, it was theglobal-warming-driven ocean anoxia that stands out as the primary agent ofArmageddon. And in this reaper of the Paleozoic, the study’s authors see afuture menace.
或许，海洋曾经开始分层，导致营养缺乏，浮游植物最终受害。或许，海洋可能因为缺氧窒息了一切，又或者是因为温度太高了。一些古生物学家直接投降了，他们屈服于这种对二叠纪末期杀戮机制的多元决定论，提出了一个不够优雅的“东方快车谋杀案”的大规模灭绝假说，该假说暗示了所有这些元凶的存在。然而，一项新的研究声称已经从这场谋杀者之争中找出了罪魁祸首：在一系列与地球有史以来最严重的灾难有关的非常糟糕的事情中，全球变暖导致的海洋缺氧是世界末日的罪魁祸首。在这个古生代的死神身上，这项研究的作者看到了未来的威胁。[/copy]
“I think this study shows the end of the road that we’re headingdown,” says the lead author, Justin Penn of the University of Washington, aboutour modern, warming, and increasingly suffocating oceans.
“我认为这项研究表明了我们前进道路的尽头，”研究报告的主要作者、华盛顿大学的贾斯汀·佩恩在谈到我们现代的正在变暖并且越来越令人窒息的海洋时这么说道。
As we’ve known since the 1860s, carbon dioxide is avery important greenhouse gas, and if you increase the amount of it in theatmosphere, it makes the planet warmer. At the end of the Permian, thevolcanoes of Siberia, by burning through a giant basin filled with coal andother carbon-rich rocks, emitted enough carbon dioxide to warm the planet by asweltering 10 degrees Celsius or so. Coincidentally, this is about the samemagnitude of warming predicted for humanity in a modern burn-it-all scenario.
我们自19世纪60年代开始就知道，二氧化碳是一种非常重要的温室气体，如果你增加它在大气中的含量，它就会使地球变暖。在二叠纪末期，西伯利亚的火山通过燃烧一个巨大的盆地——这个盆地充满了煤和其他富含碳的岩石——释放出的二氧化碳足以使地球变暖10摄氏度左右。无巧不成书的是，在现代“焚尽所有”的场景下，它与人类预测到的变暖幅度是大致相同的。
“If we are truly the stupidest intelligent species ever, we probablycould do the same thing,” says Curtis Deutsch, a co-author on the study. “As itis, we’re headed toward 3 to 4 degrees Celsius of warming by the end of thecentury, which is nothing to sniff at. But 10 degrees isn’t that off thecharts.”
“如果我们真的是有史以来最愚蠢的聪明物种，我们可能会做同样的事情，”这项研究的合著者之一柯蒂斯·多伊奇说道，“事实上，到本世纪末，我们将面临3到4摄氏度的升温幅度，这没什么大不了的。但10度也不算离谱”。
[copy]As the world warmed 10 degrees more than 250million years ago, up to 96 percent of species in the ocean went extinct (forcomparison, roughly zero percent of modern species in the ocean have goneextinct so far in what’s been called “the sixth extinction”). For all theplanet knew, it was time for complex life to close up shop after a nicequarter-billion-year run. After several millennia of eruptions from the SiberianTraps, the fossil record remained startlingly impoverished for almost 10million years, before limply convalescing in the ensuing Triassic period.
2亿5千万年前，随着全球变暖10度，多达96%的海洋物种灭绝了(相比之下，在所谓的“第六次灭绝”中灭绝了的现代海洋生物所占比例趋近于零)。据我们所知，在经历了2.5亿年后，对复杂的生命而言，是时候关门大吉了。在西伯利亚暗色岩几千年的爆发之后，化石记录在之后近1000万年的时间里仍然惊人地贫乏。
To tease out what was primarily responsible for allthis death in the oceans—in this, “the Great Dying”—Penn and his colleaguesdeveloped a climate model, not dissimilar to those used to project futurewarming on our own modern world. Only in Penn’s model, the continents werereunited. This was Pangaea, the mythic supercontinent that reached itsapotheosis in the Permian period, joining Morocco with New Jersey and Indiawith Antarctica. Then the team lit this ancient world on fire.
为了梳理出海洋生物灭绝——也就是这次“大灭绝”事件——的主要原因，佩恩和他的同事们开发了一个气候模型，它与那些用来预测我们现代世界未来变暖的模型没有什么不同。只是在佩恩的模型中，大陆重新连成了一片。这就是盘古大陆，一个神话般的超级大陆，在二叠纪达到了它的登峰造极的程度，当时它将摩洛哥、新泽西、印度和南极洲连在了一起。然后这个团队在这个古老的世界点了一把火。[/copy]
By jacking up the CO2 in their model high enough,Penn and his colleagues were able to re-create the scorching temperatures ofthe end-Permian mass extinction, searing their ancient climate model maps inworrying shades of red. The flip side of a hot ocean is one with less oxygen,and it has long been known that the oceans of the end-Permian were gasping forthe stuff. This paleoceanographic fact has been uncovered by geologists whohave found the sickly presence of laminated, pyrite-rich ocean rocks inend-Permian rock outcrops around the word—from the Salt Range in Pakistan tothe old whaling redoubt of Spitsbergen in the Arctic Ocean. Even subtler,uranium isotopes in rocks from the catastrophe whisper dark rumors about theasphyxiation of the entire ancient ocean.
佩恩和他的同事们通过将模型中的二氧化碳提升到足够高的浓度，重新创造出了二叠纪末期大灭绝时的灼热温度，在这个模型中，令人担忧的红色阴影炙烤着他们的古老气候模型地图。高温海洋的另一面是含氧量变得更少，而二叠纪末期的海洋一直渴望得到这种物质，这一点早已为人所知。地质学家们已经发现了这一古海洋学事实，他们在世界各地的二叠纪末期露出地表的岩石——从巴基斯坦的盐层到北冰洋斯匹次卑尔根的捕鲸堡垒——中发现了层状的富含黄铁矿的海洋岩石。甚至更微妙的是，灾难中岩石中的铀同位素也在散布着关于整个古代海洋被窒息的黑暗谣言。
By driving up the temperature in his model, Pennre-created this end-Permian oxygen loss as well. This is because oxygen is lesssoluble in hot water, so heat alone can cause oxygen to plummet in the ocean.But a hotter ocean is also a more sluggish and stratified one, so the depthsbecome starved of oxygen’s delivery as well. Even worse, the hotter it gets,the more oxygen animals need to power their metabolism, so hot water quicklycreates a crisis of supply and demand. By populating his model ancient oceanwith modern creatures, such as sharks and crabs and corals—creatures with avariety of tolerances to things like deoxygenation, temperature, and pH—andthen letting all climate hell break loose, Penn found that it was theheat-driven loss of oxygen in the ocean, more than any other factor, that couldexplain the end of the world.
通过在他的模型中提高温度，佩恩也重构了二叠纪末期的氧气损失情况。这是因为氧气在热水中溶解性较差，因此仅凭热量就能使氧气在海洋中的浓度急剧下降。但是一个更热的海洋也是一个流动更慢和分层了的的海洋，所以深海也变得缺氧了。更糟糕的是，温度越高，动物新陈代谢所需的氧气就越多，因此热水很快就会造成供需危机。通过将现代海洋生物——如鲨鱼、螃蟹和珊瑚——也就是对于脱氧环境、温度和酸度有着不同耐受度的生物放入这一古代海洋模型中，然后让所有的气候地狱挣脱牢笼，佩恩发现海洋中，温度升高所驱动的氧气损失比任何其他因素更能够解释这个世界末日。
[copy]While essentially nothing was spared in this massextinction, it appears from the fossil record that life at the poles wasespecially marked for destruction. And this makes sense in a world losing itsoxygen. There’s more oxygen in colder waters at the poles, so the creaturesthere have adapted to it—and are especially sensitive to its diminishment.Meanwhile, tropical creatures are adapted to warmer, more oxygen-poor waters. Soif anyone is to survive on a world that’s about to become outrageously hot andlose three-quarters of its oxygen, it will be those hardy inhabitants of thelow latitudes. And that’s what’s seen in the fossil record. The tropics stillfaced an unthinkable cataclysm, but they fared mildly better. The predicamentfor polar creatures was not unlike those luckless creatures that today inhabitthe tops of mountains, and that will have no higher altitude to which to escapein the coming decades. “They’re shit out of luck,” Deutsch says.
虽然在这次大灭绝中基本上没有任何生物幸免，但从化石记录来看，两极的生命似乎特别容易被毁灭。这在一个失去氧气的世界里是合理的。极地较冷水域的氧气更多，所以那里的生物已经适应了富氧的环境，而且对氧气的减少特别敏感。与此同时，热带生物适应了更温暖、更缺氧的水域。因此，如果有人想在一个即将变得异常炎热并失去四分之三氧气的世界上生存下去，那一定是那些低纬度地区的顽强居民。这就是我们在化石记录中看到的。热带地区仍然面临着一场无法想象的大灾难，但它们的境况略好一些。极地生物所面临的困境，与今天生活在山顶上的那些不幸的生物没有什么不同，在未来几十年里，它们将没有更高海拔的场所可以逃避。“它们非常倒霉，”多伊奇说。
When the ocean loses its oxygen, it’s something ofa great leveler compared with other hypothesized mass-extinction mechanisms.Ocean acidification, for instance (what happens when too much CO2 reacts withseawater), has previously been proposed as the great killer of the end-Permian.But while acidification can have a surprisingly variable effect on the survivalof different kinds of sea life, there is hardly any selectivity at all whenoxygen disappears from an ecosystem. Everyone dies, matching the near-universalsignal of slaughter in the ancient ocean.
当海洋失去氧气时，与其他假设的大规模灭绝机制相比，它就变成了一个很好的平衡器。例如，海洋酸化(当过多的二氧化碳与海水发生反应时的结果)曾被认为是二叠纪末期的主要杀手。然而，尽管酸化对不同种类海洋生物的生存有着令人惊讶的可变影响，但当氧气从生态系统中消失时，却几乎没有任何选择性。所有生物都会死去，这与古代海洋中近乎普遍的屠杀信号是相吻合的。[/copy]
“This study suggests we should be worrying much more about hypoxiathan about ocean acidification,” Deutsch says. “There’s vastly more resourcesbeing put into [studying] organisms’ responses to pH in seawater than there isinto understanding temperature-dependent hypoxia. I think that the field hasbasically allocated those resources in exactly the wrong way.”
多伊奇说：“这项研究表明，我们应该更多地担心缺氧的情况，而不是海洋酸化。人们投入(研究)生物对海水酸性的反应的资源要远远多于投入理解取决于温度的缺氧情况的资源。我认为，该领域基本上是以一种完全错误的方式分配了这些资源”。
The modern oceans have already lost 2 percent oftheir oxygen since 1960, a remarkable loss driven mostly by coastal nutrientpollution and global warming. It’s an environmental problem that promises toworsen in the warmer world of the coming centuries, just like it did in theend-Permian. And if Earth’s past is any indication of its future, thisasphyxiation could be truly world changing. The prospect has led dozens ofpaleoclimatologists, geochemists, and oceanographers to sign the KielDeclaration on Ocean Deoxygenation, developed this September to raise globalawareness of a problem with increasingly worrying geological precedent.
自1960年以来，现代海洋已经失去了2%的氧气，这一显著损失主要是由沿海营养污染和全球变暖造成的。就像二叠纪末期一样，在未来几个世纪气候变暖的世界里，这一环境问题注定会趋于恶化。如果地球的过去能预示它的未来，那么这种窒息可能会真正改变世界。这一前景促使数十名古气候学家、地球化学家和海洋学家签署了《基尔海洋脱氧宣言》。该宣言于今年9月制定，旨在提高全球对这个日益令人担忧的地质先例问题的认识。
“This study shows that we’re on that same road toward extinction, andthe question is how far down it we go,” Penn says.
佩恩说：“这项研究表明，我们正走在同一条灭绝的道路上，问题是我们还能走多远。”
[copy]To head off warming and drastic deoxygenation ofthe oceans, humanity can either stop burning fossil fuels or artificially dimthe amount of sunlight reaching Earth’s surface—a kludgy solution that goes bythe name of geoengineering. One of the most hotly debated methods ofgeoengineering would involve shooting sulfate aerosols out of planes and intothe atmosphere to reflect sunlight back into space. Unfortunately, says theCity College of New York geoscientist Benjamin Black, the end-Permian massextinction represents something of a proof of concept for the idea, and it’snot pretty.
为了阻止海洋的变暖和剧烈的脱氧进程的发生，人类可以停止燃烧化石燃料，或者人为地减少到达地球表面的阳光——这是一个被称为地球工程的笨拙解决方案。地球工程中争论最激烈的方法之一是将硫酸盐气溶胶从飞机中射入大气层，将阳光反射回太空。不幸的是，纽约城市学院的地球科学家本杰明·布莱克说，二叠纪末期的大灭绝在某种程度上证明了这一观点的正确性，而且前景并不美妙。
In a paper published last week in NatureGeoscience, Black and his co-authors describe not only the extreme warming ofthe climate around 252 million years ago, but also the extreme climatewhiplashes that throttled the planet on much shorter timescales. Theseenvironmental seesaws, the researchers show, were induced by volcanic sulfurdioxide from the Siberian Traps, which would have briefly cooled the planet andmasked the warming before being rained out of the atmosphere and allowing theplanet to jump back into the high-CO2 inferno. Similarly, if humans embark on ageoengineering project of shooting sulfur dioxide into the air to head off allof the problems of warming, without drastically reducing the concentration ofCO2 in the atmosphere—and if they ever give up on this project after it starts,for whatever reason, at any time in the next few thousand years—Black canimagine a similar disaster unfolding.
在上周发表在《自然·地球科学》杂志上的一篇论文中，布莱克和他的合著者不仅描述了大约2.52亿年前气候的极端变暖，而且还描述了在短得多的时间尺度内让地球窒息的极端气候冲击。研究人员表示，这些环境上的“跷跷板”是由西伯利亚暗色岩喷发出的火山二氧化硫引起的，这些火山喷发的二氧化硫会使地球短暂变冷，并掩盖了气候变暖的事实，然后被雨水从大气中带走，让地球重新跳入高二氧化碳的地狱。同样地，如果人类启动了将二氧化硫排入空气以阻止全球变暖问题的地球工程项目，而不是去大幅度削减空气中的二氧化碳浓度——而且如果他们在开始之后又放弃了这个项目，那么不管出于什么原因，在接下来的几千年时间里，布莱克都可以想象得到一场类似灾难的发生。[/copy]
“So if you think about the Siberian Traps and the end-Permian massextinction as a feasibility study for global warming and sulfur geoengineering,the results of that study were … not the best,” he said, referring to, quiteliterally, the worst thing that’s ever happened. “It’s worth asking ourselveswhether we really want to make our current predicament even more like theend-Permian mass extinction.”
“所以，如果你把西伯利亚暗色岩喷发和二叠纪末期的大灭绝看作是全球变暖和硫地球工程的可行性研究，那么这项研究的结果并不是最好的，”他说，“我们有必要扪心自问，我们是否真的想让我们目前的困境看起来更像是二叠纪末期的大灭绝事件。”
|
