By that reasoning nearly everyone has improved the world. Considering the negative impact we all have just existing in our society I'm sure his stance is more accurate.
Is your belief based on human impact on the environment, or is it something else?
[1] Better resources a Google away but this is something at least. http://www.economist.com/node/8908438 [2] http://www.stier.net/writing/demstab/demstab.htm#_Toc5203975...