Biomass Census

A study published by PNAS finds that humans represent just 0.01 percent of life on Earth.

And yet, humans and our livestock comprise 96 percent of all mammals. Our ability to exploit resources has had an enormous impact.

The researchers estimate that, in terms of biomass, the so-called rise of human civilization has destroyed 83 percent of wild mammals, 80 percent of marine animals, 50 percent of plants, and 15 percent of fish.

Update (June 2):  The original paper makes it clear "biomass" is not the same as living tissue--most of a tree, for example, is inert.

Update (September 11):  A paper published by PNAS uses "scaling laws" to predict the Earth may have up to one trillion microbial species.