Saturday, December 8, 2007

Revised Deficits

Taking another look at the concept of “unprocessed waste” described in the previous post, I now realize that the ecological footprint already includes that waste in its definition. That is, unprocessed waste is really the difference between the footprint and the biocapacity.

By this more correct definition, our footprint will exceed available biocapacity by an amount equal to that biocapacity (that is, our waste will equal the world’s biocapacity) when my consumption model projects our population to peak.

Using the ratio of Gross World Product to ecological footprint as a measure of the value of each unit of bio-productive land, the 1997 value of available biocapacity comes close to the high end of the benchmark value of Nature’s services: $43 trillion (in 2007 dollars) by my new estimate, versus $28T to $45T in the benchmark estimate. The value of the fraction of biocapacity usable by humans while accommodating other species in 1997 would have been $36T by my estimate, marking the maximum GWP we could have had to keep other species from dying off.

I estimate that the current maximum GWP for accommodating other species is $41T, and project our actual GWP to be $66 T; with a difference of $25 T (matching the “maximum Nature deficit” I calculated using fixed biocapacity). Without other species, the maximum GWP is the current value of biocapacity, or $48 T, with a deficit of $18 T (versus the $9 T that I estimated earlier). In ecological terms, we have an estimated footprint of nearly 15.9 billion global hectares (Bh) and a biocapacity of 11.5 Bh, of which other species need 2.1 Bh.

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