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地球最热的年代 [Copy link] 中文

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Post time 2012-7-6 21:55:01 |Display all floors
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地球表面温度最高的情况大约发生在40亿年前,当时一个火星大小的原行星撞击了当时的地球,被撞飞的碎片形成了当时的月亮,而当时地球的温度高达华氏3700度,足以让海洋沸腾岩石蒸发。经过一千年左右地表温度降低到华氏3000度,然后我们这颗行星经历了几千万年的冷却期,吸热水云和二氧化碳让大气层变厚,地表也形成坚硬的岩石外壳,温度稳定在华氏440度。

在哺乳动物从生命树中诞生分支以来,最热的天气则是距今约5500万年前,被称作“古新世-始新世交替时期”(Paleocene-Eocene Thermal Maximum),那是地球的发烧期,因为大量的碳排放而让地球极速而剧烈的变暖。据说当时排放的碳量相当于人类把当今地球所有的煤、石油和天然气矿藏全部烧光的总和。古/始新世交替时期的最大热量历时超过15万年,直到多馀的碳重新被吸收才告终。它带来了乾旱、洪水、虫灾,也造成了一些物种灭绝。

在最近几千年,地球表面的温度上升了5-10度。对整个地球来说,几度的温度上升会带来很大的变化,事实上我们现在的温度已经接近3000万年前上新世的温度,能让物种大量灭绝的温度。【jandan.net】

Hot enough to boil oceans and vaporize rock. The highest terrestrial temperatures occurred more than four billion years ago, when a Mars-size proto-planet smashed into the Earth. (The debris from this collision formed our moon.) Within a millennium, the surface air temperature had dropped from a high of about 3,700°F down to 3,000°. Then the planet went into a period of slower cooling that lasted a few tens of millions of years. As the atmosphere thickened with heat-trapping water clouds and carbon dioxide and a shell of solid rock formed around the Earth’s core, conditions stabilized at 440°.

The warmest weather we’ve had in recent times—since mammals diverged from the tree of life—came about 55 million years ago, during a period known as the Paleocene-Eocene Thermal Maximum. In just a few thousand years, global surface temperatures increased by 5° to 10°, with parts of North America experiencing a tropical climate and spring-like average temperatures in the Arctic.

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