经济学人70:甲烷释放可能是恐龙称霸地球的原因

 　　Science and Technology The rise of the dinosaurs 1 Pardon!

　　科技 恐龙的崛起 恕我直言!
　　A geological burp may have led to the dinosaurs' domination
　　地质上的甲烷释放可能是恐龙称霸地球的原因
　　THE s, famously, went out with a bang.
　　众所周知，恐龙在地球上是突然消失的。
　　Some 65.5m years ago, at the end of the Cretaceous period, the Earth collided with an asteroid 2 and the biggest terrestrial beasts in history were no more.
　　大约在6500万年前的白垩纪末期，地球与小行星相撞导致最大的陆地兽类全部灭绝。
　　That left things clear for the rise of the mammals.
　　此次灭绝事件为哺乳动物的崛起提供了契机。
　　But how did the dinosaurs rise to power in the first place?
　　但首要的是恐龙是如何崛起的呢？
　　Some light on this question has just been shed by a paper published in Science by Micha Ruhl of Utrecht University, in the Netherlands, and his colleagues.
　　荷兰乌得勒支大学迈克尔·鲁尔及其同事在最近一期《科学》杂志上撰文对此问题进行了阐述。
　　Dinosaurs first appear in the fossil record during the Triassic period, some 230m years ago.
　　恐龙最早出现在三叠纪时期(距今约2.3亿年)的化石记录中。
　　They do not take over, though, until the end of the Triassic, 201m years ago.
　　但直至三叠纪末期(距今2.01亿年)恐龙才取得地球霸主地位。
　　That date marks one of five recognised mass extinctions in history (the end of the Cretaceous was another).
　　历史公认的5次物种大灭绝事件之一就是以三叠纪末期为标志的（另一次发生在白垩纪末期）。
　　In it, half the world's known species disappeared.
　　在此期间，世界上的半数已知物种都灭绝了。
　　Until now, the end of the Triassic has been blamed on massive volcanic 4 eruptions 5 that went on for 600,000 years.
　　直到现在，人们都一直将三叠纪的终结归因于持续了60万年的大规模火山喷发。
　　Dr Ruhl, however, reckons that was not the cause—or, at least, not directly.
　　然而鲁尔博士却认为火山喷发不是导致三叠纪终结的原因或者至少不是直接原因。
　　By analysing the isotopic 6 composition of hydrocarbon 7 molecules 8 from plant waxes of the period, he found what looks like a spike 9 in the amount of recently non-biological carbon (which has a distinctive 10 ratio of light isotopes 11 to heavy ones), lasting 12 between 10,000 and 20,000 years.
　　通过分析该时期植物腊的碳氢分子同位素组成，他发现有种类似最近非生物碳（轻、重同位素有着独特的比例）的碳元素在数量上激增，这种现象持续了1万到2万年。
　　He thinks the liberation of methane 13 stored at the bottom of the ocean in structures called clathrates is the most likely culprit.
　　他认为出现这种现象的最可能诱因是甲烷气体的释放,这些甲烷气体释放前存储在海底称作"笼形包合物"的结构中。
　　The alternative, that the carbon came from the volcanoes, is unlikely because the spike is much shorter than the period of volcanic activity.
　　另一种说法是这种碳元素来自于火山，但这不可能，因为碳数量激增期比火山活动期要短得多。
　　Methane is a greenhouse gas far stronger than carbon dioxide, so the consequence would have been a rapid warming of the climate—a phenomenon that the rocks suggest did actually happen.
　　甲烷是一种比二氧化碳浓烈得多的温室气体，它的释放会导致地球气候迅速升温——岩石层研究也表明这种现象确实发生过。
　　This is not the first time a methane burp has been blamed for an extinction 3.
　　人类已经不是第一次将物种灭绝归因于甲烷气体的脉冲式释放。
　　Though the Cretaceous asteroid cleared the stage, mammals did not really get going until 10m years later, in the Eocene epoch 14.
　　尽管白垩纪时期的小行星灭绝了居统治地位的恐龙，但哺乳动物却一直到1000万年后的始新世才真正兴起繁盛起来。
　　The preceding Palaeocene epoch was also brought to an end, the rocks suggest, by a sudden release of methane.
　　岩石层研究表明甲烷的突然释放导致了之前的古新世时期结束。
　　The burp could, of course, have been provoked by the eruptions, so the volcanoes are not off the hook completely.
　　当然甲烷的脉冲式释放可能是火山喷发所致，因此火山始终难辞其咎。
　　But, for those of a nervous disposition 15, the tying of an ancient greenhouse warming to an ancient mass extinction might suggest lessons for the future.
　　但是对于这些性情冲动的火山，古代的温室变暖和古代大量物种灭绝之间的联系或许对未来有诸多的借鉴意义。