Because we've only doubled the population of the Earth since the 1960s -- a little more than doubled -- but we have 6.7 billion people in the world, and we all like to consume.
因为地球上的人口仅翻了一番， 自20世纪60年代起，两倍稍微多一些。 但是全世界有67亿人， 而且我们都喜欢消费。