http://www.stephaniemcmillan.org/codegreen/2011/10/31/future-paperweights-2/

It is difficult to judge the level of biodiversity that would exist right now without the negative human impact.  And it is difficult to estimate for sure the species extinction rate, especially when it pertains to factors like a human impact.  But in May, 2007 Ahmed Djoghlaf, head of the U.N. Convention on Biological Diversity, said that, "Extinction rates are rising by a factor of up to 1,000 above natural rates. Every hour, three species disappear. Every day, up to 150 species are lost."