这些现象在过去40万年中都没有过。 由于目前的现象还只是由25%的人口产生的，随着不断的发展，环境还将恶化。
Indeed, these concentrations are higher than at any point in the past 400 millennia, with more growth to follow, because so far these effects have largely been caused by only 25% of the world population.