From our smartphones to our latest weaponry, the technology that underpins  modern life would be impossible without rare earth metals.  The importance of rare earths has only grown as emerging markets increase their demand for technologies made with it, as does the renewable energy industry. The 17 metallic elements are common in the earth-s crust, but the technique used to extract and refine them is labor-intensive, environmentally hazardous and increasingly costly.  Thomas Gradael,  a professor of geology and geophysics at the Yale School of Forestry Environmental Studies, explains that thecriticality" of rare earths was only recently understood after China, which dominates the world-s supply of the minerals, cut exports by 40% in 2010, citing concerns over how polluting the rare earth industry was. Along with colleagues at Yale, Gradael decided to investigate the metals used in modern technologies to determine if there were viable  substitutes."Twenty or thirty years ago electronics were being made with 11 different elements," explains Gradael.  "Today's computers and smartphones use something like 63 different elements." Their findings showed that there were no "readily apparent" substitutes for a metal that would not compromise on quality or performance. However increased mining for these scarce resources can have some nasty side effects for the environment. China, which has intensively mined for rare earths with little regulation, allowing it to dominate the global industry since 1990, has acknowledged the incredible environmental harm caused by the process.  "Excessive rare earth mining has resulted in landslides, clogged rivers, environmental pollution emergencies and even major accidents and disasters, causing great damage to people's safety and health and the ecological environment," read a white paper issued by the Chinese cabinet in June last year. Recycling metal has been advocated by some as a possible way of managing these precious resources-the European Parliament adopted a law curbing dumping of electric waste in 2012. But Gradael says that for rare earths, recycling will have little impact. Why does the author take China as an example in Para.4?
To tell the wide use of rare earth in China. To prove the side effects of rare earth mining. To warn people of the possible damage. To teach other countries a lesson to follow.