专业英语4-new.ppt

The political feasibility of instituting such a ban by 2000 is also doubtful, because only a worldwide agreement to curtail emission could be successful. Any individual nation that curtails its own emissions will delay the day when CO2 concentrations double by a few years at most. Furthermore, because energy costs would increase for any nation that curtails its emissions, that nation’s industries would be placed at a competitive disadvantage compared with those of the rest of the world. Finally, political leaders would require proof that such a policy would be more beneficial than adapting to higher CO2 levels. Such proof will probably remain impossible to provide for the foreseeable future. 最后，政治家们也会要求提供证据来证明这样的政策比适应较高浓度的CO2更有益。在可预见的未来，提供这样的证据也许仍然是不可能的。 The impact of increasing concentrations of greenhouse gases will almost certainly be an unprecedented global warming. Some people have suggested that this warming may be offset because the earth would otherwise be entering a cool period. However, a natural cooling would take place over tens of thousands of years and is thus unlikely to significantly offset the global warming in the next century. Even a drastic increase in volcanic activity would offset less than 10 percent of the projected rise in sea level. To meet the challenge of a global warming, society will need accurate information concerning the likely effects of sea level rise. Unfortunately, communities, corporations, and individuals do not by themselves have sufficient resources or incentives to undertake the basic scientific research required to reduce existing uncertainties. This responsibility falls upon national governments throughout the world. Only their efforts can provide the information that decision makers will need. Unit Four: The Greenhouse Effect第四课 温室效应 New Words triple 三倍于 quadruple 四倍于 National Academy of Science 国家科学院 impact 影响 effect feedback 反馈 positive(negative) feed