即将从身边逝去的一个世纪，是人类有史以来发展最快的一个世纪。但物质文明的高度发展却带来了难以避免的负面影响。天空不再如往日那般澄净，空气也没有以前清新，气温也变得越来越反常……
　　专家们指出，全球气温上升，与人类活动燃烧了大量的煤、石油等燃料并向大气中排放大量温室气体有很大关系。全球社会应站在可持续发展的高度，来控制人类活动对大气环境的影响，减缓全球气候变暖的趋势。

　Global Warming
　　　　　　　　　　　　　　　　　　　　　　　

　　In spite of the obvious truth that we cannot sustainably continue to burn fossil fuels[1] at the rate we have been, their use only slackened[2] briefly during the 1974 energy crisis.The burning of fossil fuels is a key resource to our way of life, and they are unrenewable, but the immediate problem of the carbon dioxide that their combustion[3] produces, and the subsequent effect of carbon dioxide on our environment are becoming more and more serious.
　　For those who are still inclined to argue that Mother Nature is prepared to deal with all of this output, consider that we're pumping three to four times as much carbon into the atmosphere, annually, as any year of natural events would cause. And we're making this atmospheric change at an unprecedented rate[4]. The cycles[5] we can detect from Earth's past may or may not apply to our current situation.
　　We don't know for certain[6] that global warming is happening. What we can be certain of is that if we keep going as we have, it will. In a mere 500 years, we will have increased the carbon dioxide in the atmosphere by a factor of 10[7].
　　The potential effects of global warming are extreme, with only a few degrees change needed to produce massive floods, the withdrawal of forests, and the death of species or entire ecosystems[8]. Dr. Thomas Lovejoy, of the Smithsonian Institute, comments: "I fail to see that there's any conclusion to draw from all of this other than that there will be massive extinction no matter what we do in the way of conservation. Therefore, the only logical conclusion is to prevent as much of the climate change as possible."