Re Extra Earths

I am somewhat embrassed, since posting that request, and using Google, I was able to answer my own question. Apparantly the concept begins with a book written by William Rees and Mathis Wackernagel in their best-selling book Our Ecological Footprint.

 

This site http://www.newdream.org/intl/ mentions it and provides this footnote:

 

Wackernagel et al. “National Natural Capital Accounting with the Ecological Footprint Concept,” Ecological Economics, Volume 29, Number 3, June 1999, pp. 375-390.  [The “four extra planets” estimate represents a recalculation from the “two extra planets” estimate offered in Our Ecological Footprint.]

 

Here http://iisd.ca/didigest/may97/2may97.html I found an elaboration on Ecological Footprints.

 

At this site http://esa.sdsc.edu/bulletinhumanpop.htm, I found the following quote:

 

William Rees, also of the University of British Columbia, introduced the concept of the "ecological footprint," or the amount of land needed to sustain a population and its consumptive habits, contending that if the current consumption rates of industrial countries were to spread to lesser developed nations, an area equivalent to two extra planets would be needed to sustain human life

 

On this site http://www.global-vision.org/un/position.html I found the following quote from Rees' book:

It thus becomes quickly obvious that the developed countries have a global footprint. For example, William Rees estimates that the footprint of the Netherlands - for food production alone - appropriates between 100,000 and 140,000 square kilometres of agricultural land, mostly in the third world. He goes on to say:

"This 'imported land' is five to seven times larger than the area of Holland's domestic arable land... It is worth remembering that Holland, like Japan, is often held up as an economic success story and an example for the developing world to follow. Despite small size, few natural resources, and relatively large populations, both Holland and Japan enjoy high material standards and positive current accounts and trade balances as measured in monetary terms. However, our analysis of physical flows shows that these and most other so-called 'advanced' economies are running massive, unaccounted ecological deficits with the rest of the planet... Even if their land area were twice as productive as world averages, many European countries would still run a deficit more than three times larger than domestic natural income. These data emphasise that (most developed countries) are over-populated in ecological terms - they could not maintain themselves at current material standards if forced by changing circumstances to live on their remaining endowments of domestic natural capital. This is hardly a good model for the rest of the world to follow!

Ecological deficits are a measure of the entropic load and resultant 'disordering' being imposed on the ecosphere by so-called advanced countries as the unaccounted cost of maintaining and further expanding their wealthy consumer economies. This massive entropic imbalance invokes what might be called the first axiom of ecological footprint analysis: On a finite planet, not all countries or regions can be net importers of carrying capacity. This, in turn, has serious implications for global development trends.

The current objective of international development is to raise the developing world to present first world materials standards. To achieve this objective, the Brundtland Commission argued for 'more rapid economic growth in both industrial and developing countries' and suggested that 'a five to ten-fold increase in world industrial output can be anticipated by the time world population stabilises some time in the next century.' (WCED, 1987).

Let us examine this prospect using ecological footprint analysis. If just the present [January 1996] world population of 5.8 billion people were to live at current North American ecological standards (say 4.5 ha/person), a reasonable first approximation of the total productive land requirement would be 26 billion hectares (assuming present technologies). However, there are only just over 13 billion hectares of land on Earth, of which only 8.8 billion are ecologically productive cropland, pasture, or forest (1.5 ha/person). In short, we would need an additional two planet Earths to accommodate the increased ecological load of people alive today. If the population were to stabilise at between 10 and 11 billion sometime in the next century, five additional Earths would be needed, all else being equal - and this just to maintain the present rate of ecological decline (Rees and Weinberger, 1994).

While this may seem to be an astonishing result, empirical evidence suggests that five phantom planets is, in fact, a considerable underestimate (keep in mind that our footprint estimates are conservative). Global and regional-scale ecological change in the form of atmospheric change, ozone depletion, soil loss, ground water depletion, deforestation, fisheries collapse, loss of biodiversity, etc., is accelerating. This is direct evidence that aggregate consumption exceeds natural income in certain critical categories and that the carrying capacity of this one Earth is being steadily eroded. In short, the ecological footprint of the present world population/economy already exceeds the total productive land area (or ecological space) available on Earth.

This situation is, of course, largely attributable to consumption by that wealthy quarter of the world's population who use 75% of global resources. The WCED's 'five to ten-fold increase in industrial output' was deemed necessary to address this obvious inequity while accommodating a much larger population. However, since the world is already ecologically full, sustainable growth on this scale using present technology would require five to ten additional planets." (20)

This site offers an informative essay on American consumption: http://bostonreview.mit.edu/BR24.3/taylor.html