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Rare earths and climate change 稀土与气候变化 In a hole? 陷入了危机? Demand for some rare-earth elements couldrapidly outstrip supply 某些稀土元素可能很快会供不应求 MANY plans for reducing the world s emissions ofcarbon dioxide-at least, those plans formulated byenvironmentalists who are not of the hair-shirt, back-to-the-caves persuasion-involvepeppering the landscape with wind turbines and replacing petrol-guzzling vehicles withelectric ones charged up using energy gathered from renewable resources. The hope is thatthe level of CO2 in the atmosphere can thus be kept below what is widely agreed to be theupper limit for a tolerable level of global warming, 450 parts per million. 许多全球性减排二氧化碳的计划是要建造星罗棋布的风力涡轮发电机，并以再生能源发电为电动汽车充电，摈弃狂吞汽油的汽车。哦，至少那些并不坚决主张严酷节俭、回返穴居社会 [注] 的环保主义者是这样计划的。人们希望，这样一来，大气中CO2的含量可以保持在百万分之450以下。人们普遍认为，这就可以让全球气候变暖的程度处在可容忍的上限以下。 Wind turbines and electric vehicles, however, both rely on dysprosium and neodymium tomake the magnets that are essential to their generators and motors. These two elements,part of a group called the rare-earth metals, have unusual configurations of electronsorbiting their nuclei, and thus unusually powerful magnetic properties. Finding substituteswould be hard. Motors or generators whose magnets were made of other materials would beheavier, less efficient or both. | 
