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冰河时代为什么地球没有完全封冻?

时间:2010-07-29 13:07    来源:    作者: 点击:
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    Research published in the July 2 issue of Nature reveals one reason our planet didn't succumb to an enveloping ice sheet during glacial ages.

    揭晓在7月2日的《自然》(Nature)杂志上的一项研究展现了地球在冰河期间没有完全封冻的一个缘故起因。

    Why Didn't Earth Freeze Completely?

    During the last ice age our problem was too little carbon. Unlike today where too much carbon is causing global warming.

    Past glacial ages occurred partly because the weathering of rocks, over millions of years, pulls CO2 from the atmosphere, locking it in ocean floor sediment. The rise of global mountain ranges during the last 25 million years should have sucked all the CO2, sending the Earth to an icy death.

    But that never happened. CO2 levels stabilized at about 250 parts per million.

    This week in the journal Nature, researchers announce one reason why this happened: plants.

    Leafy greens need CO2 to live, and when CO2 levels drop significantly they starve. Researchers say that the plant numbers decreased to a level where volcanoes and other carbon-creating sources produced CO2 faster than the remaining plants could remove it. So the Earth remained somewhat warm.

    It may seem that our leafy friends could help us now, this time from overheating. But ultimately we're producing too much CO2 too fast for natural weathering processes to remove it. Ultimately, we need a way to stop producing CO2 in the first place.

    冰河期间为什么地球没有完全封冻?

    在上一个冰河期间我们的题目是二氧化碳太少。目前天过多的二氧化碳正在导致环球变暖。

    已往冰河期间产生的部分缘故起因在于在几百万年的时刻里,石头的风化领受了年夜气中的二氧化碳,然后以沉积物的情势把这些二氧化碳坚贞在海底。在已往2千5百年的时刻里,环球山脉的升高应该把年夜气中的二氧化碳全数吸完,从而让地球成为致命的冰窟。

    可是这种情形根柢没有产生。二氧化碳的浓度水平一向不变在约百万分之250.

    在本周的《自然》(Nature)杂志上,研究者们宣布揭晓了这种情形没有产生的一个缘故起因:植物。

    带叶子的绿色植物必要二氧化碳维持生命,当二氧化碳的浓度水平光鲜较着降落的时辰,它们就会"受饿".研究者们说,在冰河期间植物的数量降落到必然的水平,这样火山以及其余产碳源孕育产生二氧化碳的速率就要比所剩植物耗损二氧化碳的速率快。是以地球仍旧贯串毗邻"暖和".

    此刻看来,似乎我们的植物伴侣能辅佐我们办理过热的题目。可是归根到底我们孕育产生二氧化碳太多太快,甚至于自然的风化历程不能耗丧失多余的二氧化碳。我们终极首先必要遏制孕育产生过多的二氧化碳。

    Vocabulary:

    Reveal:展现;表现

    Succumb:屈就

    Enveloping:包裹着的;围困的

    Glacial:冰川的

    Freeze:结冰

    Occur:产生

    Weathering:风吹日晒

    Sediment:沉淀

    Stabilize:不变

    Leafy:带叶子的

    Starve:饥饿

    Volcano:火山

    Ultimate:终极的




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