Unlocking the Climate Puzzle
解开气候之谜
(1)Life has prospered on this planet for nearly four billion years. In that time, climate had fluctuated drastically, from ice ages lasting tens of thousands of years to epochs of steamy heat. With each change, sundry species have benefited and flourished.Others adapted, faltered， or died. Now, many experts believe， humans are imperiling their own ecological niche with the threat of global warming. The vaporous by—products ofland civilization， in the form of greenhouse gases such as carbon dioxide (C0₂), have trapped enough heat in the atmosphere to raise Earth's average surface air temperature a half degree Celsius (one degree Fahrenheit) during this century. If the trend continues， it could alter climate patterns worldwide-thawing glaciers， boosting sea level, scorching plains into deserts, and shifting vegetation zones。
（1）生命在这个星球上已经发展了近四十亿年。在这段时间里,气候有大幅波动，从冰河时代到蒸汽时代延续了几千年。每一次改变,各种物种受益和繁荣.其他适应，步履蹒跚,或死亡。
现在，许多专家认为,人类正在通过全球变暖危及自己的生态位。在本世纪，文明的气态副产物，以二氧化碳（C0₂)等温室气体的形式，把足够的热量困在大气中，来提高地球表面平均气温半摄氏度（1华氏度）。如果这种趋势继续下去,它可能会改变世界范围内的气候模式-融化冰川，提高海平面,把平原烤成沙漠，以及改变植被区。
(2） Or it might not. Global climate depends on combinations of factors interacting in subtle and complex ways that we do not yet fully understand。 It is possible that the warming observed during this century may have resulted from natural variations， even though the increase has been much more rapid than what the planet has witnessed over the past hundred centuries。 Moreover， the supercomputer simulations used to project future conditions may not be accurate。
（2）或者不可能。全球气候取决于各种因素的组合，这些因素以微妙和复杂的方式相互作用，我们还没有完全了解。这是可能的，在本世纪中观察到的变暖可能是由于自然的变化，即使增加已远远超过这个星球在过去的几百个世纪已经见证过的。此外，用于展现未来条件的超级计算机模拟可能是不准确的。
(3) Nonetheless， in 1995, after years of intense study， the Intergovernmental Panel on Climate Change （IPCC）, sponsored by the United Nations， concluded tentatively that ”the balance of evidence suggests that there is a discernible human influence on global climate”. The amount of that influence, the group noted， is unknown because of "uncertainties in key factors", including the degree to which clouds and the oceans affect the rate of temperature change。 It may take a decade or more of additional research to resolve those uncertainties.
（3）然而,由联合国发起的政府间气候变化专门委员会，经过数年集中的研究,在1995年,初步得到了“对照所有证据表明,人类对全球气候有明显的影响”这个结论.该委员会同时提到，由于“关键因素的不确定性”，包括云层和海洋对温度变化率的影响程度，人类对全球气候的影响量是未知的。解决这些不确定因素可能需要十年乃至更长时间的额外研究。
（4） Meanwhile， much is known. And although the specific consequences of human activity remain ambiguous， our ability to alter the atmosphere is incontestable。
（4)同时，大多是已知的.尽管人类活动的具体后果仍不明确，我们改变大气的能力是不可
否认的。
(5） What causes climate change？ Weather is what happens outside your home this morning. Climate is what you can expect to happen outside during your 30—year mortgage. Over time small changes can make a big difference. Driven by tremendous flows of heat over the surface of the planet, Earth's climate system is influenced by innumerable interacting variables.
（5）是什么导致了气候变化？天气是这个早上出现在户外的自然现象.气候是在30年内可以预测的发生在户外的自然现象.随着时间的流逝,微小的变化会造成巨大的影响。由于星球表面上的巨大热流，无数相互作用的变量影响着地球的气候系统。
Solar Input
(6) Having traveled 93 million miles， solar energy hits the upper atmosphere at about the intensity of three 100—watt bulbs per square yard—one-third of which is reflected back into space. The rest of the energy warms Earth and fuels its weather engine。 太阳能输入
（6)已经走了9300万英里，太阳能达到高层大气时，每平方的强度大约是3个100瓦灯泡—其中三分之一被反射回太空。其余的能量使地球变暖，并引起天气改变。
The Atmosphere
(7) A delicate balance of gases gives Earth an average temperature of 15℃(59℉)。 Greenhouse gases一water vapor， C0₂， methane， nitrous oxide， and others一absorb heat energy， then re—radiate a portion of it back to the surface。
大气
（7)气体的一种微妙平衡使地球平均温度为15℃(59℉）。温室气体一水汽，C0₂，甲烷,一氧化二氮，和其他气体一吸收热能，然后再辐射一部分返回地面。
The Oceans
（8) Covering 70 percent of Earth’s surface, oceans are the chief source of water vapor in the air。 Oceans store heat efficiently and transport it thousands of miles. When warm
water collects in one place， evaporation and cloud buildup may increase。 Marine organisms consume huge amounts of C0₂。
海洋
（8)覆盖地球表面的百分之70,海洋是空气中的水蒸气的主要来源。海洋能有效地储存热能和把它运输数千英里。当温水聚集在一个地方，蒸发和云层积累可能会增加.海洋生物消耗大量的C0₂.
The Water Cycle
(9) Higher air temperatures can mean increased water evaporation and the melting of sea and land ice。 Although water vapor is the most potent greenhouse gas，