But the usual causes of natural variability do not seem to explain the current trend, so scientists incline to the view that it is man-made.

但通常的自然变异原因似乎解释不了目前的趋势，所以，科学家倾向于认为这是人为的。

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Under anaerobic conditions (where oxygen is absent) they metabolise the fuel by feeding off it and in doing so produce natural chemical reactions that produce a current.

在厌氧条件下(比如缺氧的地方)通过取食产生新诚代谢并以此引起化学反应产生电流。

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The IPCC makes it plain that the current and projected climate change is not simply “natural variation”, but “very likely” (meaning at least 90%) the result of human activity.

IPCC指出，当前和预期内的气候变化并不简单是“自然的变化”，而非常可能是人类活动的结果（意思是至少90%）。

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The capital intensive setup and expensive drilling procedure leaves very low margins for the drilling companies at the current natural gas rates.

FORBES: Chesapeake Stock Drilling Its Way To $35

With improvements in petroleum and petroleum product shipping offsetting coal volume losses over the last two quarters, the railroad industry is capitalizing on the current natural gas boom.

FORBES: Norfolk Southern Chugs To $78 On Natural Gas And Housing Recovery

The Department of Energy has taken credit for laying the groundwork for the current natural gas boom, citing research and development dating back to the 1970s that led to today's hydraulic fracturing, or fracking, techniques of extracting gas from shale.

CNN: STORY HIGHLIGHTS