>In Nature v387, 15 May 1997, p283
>(Costanza et al, "The value of the world's
>ecosystem services and natural capital")
>the value of the entire biosphere is estimated
>to be "US$16-54 trillion (10^12) per year,
>with an average of about US$33 trillion/yr..."
>Global GNP is around US$18 trillion/yr.
This is interesting. It would imply that at present replacing the Earth's
natural ecosystems is not a viable option at present. However, human GNP
continues to grow, while the natural ecosystem doesn't. At 5% growth, in a
mere 43 years or so the human economy will be 4 times the size of the
benefits it derives from the natural ecosystem. At that point we could
replace the natural ecosystem with consequences no more severe than a major
depression. Kind of profound that in our natural lifetimes humanity will
become able to survive the complete obliteration of the earth's natural
ecosystems.
These results fit with my intuition that we couldn't replace the biosphere
now but that we will be able to in the forseeable future.