Unlocking the Climate Puzzle Nonetheless, in1995, 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”.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。
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.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。
It may take decade or more of additional research to resolve those uncertainties.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。
1.What causes climate change? 是什么导致了气候变化？2.Weather is what happens outside your home this morning.天气是这个早上出现在户外的自然现象。
3.Climate is what you can expect to happen outside during your 30-year mortgage.气候是在30年内可以预测的发生在户外的自然现象4.Over time small changes can make a big difference.随着时间的流逝，微小的变化会造成巨大的影响。
5.Driven by tremendous flows of heat over the surface of the planet, Earth’s climate system is influenced by innumerable interacting variables.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。
The role of clouds is poorly understood, but they are known to both cool earth by reflecting solar energy and warm earth by trapping heat being radiated up from the surface.人类对云层的作用了解很少，但是知道它们会通过反射太阳能使地面温度下降，且通过储存地表散发的热量使地面温度上升。
When solar energy penetrates the land surface, it is converted into heat, most of which radiates upward quickly.当太阳能渗入地表时，会转化为热能，其中大部分会很快上升散发到空气中。
Still, topography and land use can have major effects on climate.地形和土地使用仍然对气候有主要的影响。
Mountain ranges can block clouds, creating dry “shadows”downwind. 在下风口，山脉会挡住云层，形成缺乏雨水的“阴影地”。
Sloping land allows more water runoff, leaving the land and air drier.坡地让更多的水分流失，使得土地和空气更加干燥。
A tropical forest will soak up CO2 ,but once cleared for cattle ranching, the same land becomes a source of methane.热带森林会吸收二氧化碳，但是一旦允许牲畜农场经营，这块土地将会产生大量的甲烷。
If CO2 emission increases are to blame for global warming,skeptics say,then temperatures should have risen appreciably during the postwar economic boom,when fossil fuels were burned in escalating quantity.质疑者们说，如果CO2的增加应该对全球变暖负责，那么在战后经济繁荣期间化石燃料被越来越多的燃烧时，温度应该很明显的增加。
Jerry Mahlman,director of NOAA’s Geophysical Fluid Dynamics Laboratory at Princeton, however, has calculated that the surge in coal and oil use quickly increased the amount of sulfates aloft,prompting the cooling.不管怎样，Jerry Mahlman，美国国家海洋和大气局位于普林斯顿关于地球物理流体动力学实验室的主任，曾计算过煤和油的使用量的激增会迅速增加空气中大量的硫酸盐，并促进它们冷却。
After 1970 the longer term effect of CO2 and methane overwhelmed the short-lived aerosols,accounting for the temperature rise since then.从1970年后，CO2和甲烷覆盖了短期效应的气溶胶从而带来的长期效应，导致了温度的上升。
Furthermore,higher temperatures might be most welcome where they are most likely to occur.此外，高温在可能发生的地方也许会很受欢迎。
Science 1900,the greatest warming has been observed between 40 degrees and 70 degrees north latitude——including Europe,Russia,and the northern half of the U.S.——where much of the world’s industrial greenhouse gas emissions originate.从1990年开始，人们在北纬40°—70°之间观察最主要的温室变化。
包括欧洲、俄罗斯和美国北部半数地区，这些地区是世界上工业温室气体主要的排放地。
Most of the warming has taken place at night——presumably because increased cloud cover shades the land by day and traps outgoing heat at night.大多数的温室变化是发生在晚上的，大概是因为在白天增加的阴云遮住了大地并且晚上高温的散发受到了限制。
The growing season in the northern U.S.has lengthened by about a week. 在美国北部植物的增长期被延长了差不多一周左右。
On the other hand, there is evidence that some kinds of events could chan ge climate radically in the span of decades.从另一方面说，有证据表明一些事件会在数十年的时间内从根本上改变气候。
Perhaps the most feared is an abrupt collapse in the huge Atlantic"convey or belt"system that brings warm water north from the equator, keeping Eu rope several degrees warmer than it would otherwise be.也许人们大多数的担忧是巨大的大西洋“传送带”会发生一种突然的崩溃。
这个“传送带”从赤道北部带来了温暖的水，使它比原来的温度高几度。
Evaporation of this incoming flow leaves the belt with a higher salt conte nt than the rest or the North Atlantic, which is fed by substantial freshwat er runoff from continental watersheds.这种流入水的消失会使“传送带”变得比北大西洋其它地区的盐度都高，北大西洋其它的地区存储着大量从陆地流域流入的淡水。
The belt cools and becomes denser as it approaches Greenland,where it sinks.这个“传送带”中的水在接近格陵兰岛时会变得冰冷而且稠密，在那里它下沉了。
It then travels far below the surface in a south-moving return flow.然后它随着向南流动的回流表层下部远去。
No one knows for certain whether such things will happen.没人确信这些事情是不是真的会发生。
Beyond that the specific human effect on climate change will remain ha untingly indefinite until our knowledge increases and the models improve.除了对气候做出特别的人为影响，这种不确定性将会一直萦绕人们的心头直到我们的知识增加和理论提高。