Knowing the total resources, the consumption by other species will be that total minus our consumption. The red line shows what other species are consuming as a function of what we are consuming.
Recall that if we consumed nothing, the LPI would be 1 2/3 and other species would be consuming the total. If we divide the total by that LPI, it gives us an estimate of the consumption per unit of LPI where species are just supporting themselves. If other species don't waste anything, unlike us, then they will still be consuming that same amount to maintain themselves, and anything extra will be used to deal with new conditions, such as finding less plentiful food and fighting each other for it. That's the basis of the blue line, which shows the amount of consumption for creatures just meeting their basic needs; the difference between that and the red line is the extra they are consuming so they can get it.
If those other species are responsible for one Earth per year of resources that's renewable and we all depend on, then what will happen when their total consumption falls below one Earth per year? Can they produce less than they consume? We'll learn the answer, when, as the blue line reaches one Earth, our consumption hits 1.8 Earths per year.
© Copyright 2011 Bradley Jarvis. All rights reserved.