Here is a graph of the Living Planet Index as a function of consumption. The curve fit, shown as a dotted line, assumes that other species have their own transaction and extraction masses, and that the total amount of resources available each year on Earth is the sum of what they consume and what we consume.
If this assumption is true, then the point on the graph where the LPI reaches zero is where we will be consuming all of the resources. Put another way, the total amount of resources is about 3.1 Earths.
It is almost certain that those species are perfoming a number of important services to keep our planet habitable. When they are not around to do so, then I consider it highly probable that we won't be able to survive either.
Notice that where our consumption is zero, the LPI is about 1 2/3. If the LPI can be generalized back through time, then that means we have probably decreased the populations of other species by 61% so far.
© Copyright 2011 Bradley Jarvis. All rights reserved.