Every individual in the world uses an amount of space of planet earth. How much, depends upon one's consumption.
By means of the Ecological Footprint it is possible to render this space into an amount, expressed in hectares. The space not only implies the land needed to grow our food, the use of paper and transport require space as well. All that is eaten, worn and bought is produced somewhere and, thus, needs to be transported. Meat and diary products have a relatively large contribution to the Ecological Footprint.
It is obvious that farming land, houses and roads take up a lot of space. Energy consumption, however, requires space too. This is calculated into the amount of CO2 (carbon dioxide) expelled. For transferring CO2 into oxygen a certain area of forest is needed, etc...

The share of planet earth that does not lead to damage, so far, is about 1.7 hectares each person. People in the West obviously have a larger Ecological Footprint than the average world citizen, the latter of which is 2.3 ha.
Click here if you want to know how large your Ecological Footprint is.

  To allow each world citizen to consume as much as (s)he wants, overconsumption must some way be compensated to bring the total consumption back in balance and to make sure that what the earth can bear is not exceeded. We must also take care that there will be a healthy planet earth left for feature inhabitants. Thus, not only the polluter must pay, but also those who consume too much. It would even be better if people, who limit their consumption, are rewarded.
If we want to share the earth in a fair manner we must cede those hectares, that do not belong to us. People do not easily cut back on prosperity. It doesn't have to be necessary, but freedom, responsibility and setting limits go together. A growth of conscious and adapting lifestyles need not reduce prosperity. Furthermore, a durable lifestyle is a matter of mental growth. Overconsumption is immature and a moderate lifestyle can be a sign of mental maturity.
As yet, growth in prosperity results in an increase of (energy) consumption and environmental problems. In particular the climate suffers therefrom.

From the book "sharing Nature's Interest" by Nicky Chambers, Craig Simmons and Mathis Wackernagel we show you table 4.1. where you can see how the size of earth's population affects the remaining size for all. Pleace notice that the share of planet earth is calculated to be 1.6 ha with a population of 6 billion which is slightly larger then the current size of over 5 billion people.

In the calculations there is discriminated between two situations: the first where biodiversity is guaranteed maximally at 25% and the second, where 12% of planet earth is reserved for wild animals and plants.

Table 4.1 Average Per Capita Earthshare based on Populations of 6 and 9.5 billion
Land Type Global area (billion ha) Average earthshare (ha / per cap)  
    Population 6 billion Population 9.5 billion
Arable 1.45 0.24 0.15
Pasture 3.36 0.56 0.35
Forest 5.12 0.85 0.54
Productive sea 2.90 0.48 0.31
Total land and sea 2.13 1.35
Total minus biodiversity  
area (at 12%) 1.87 1.19
area (at 25%) 1.60 1.01
Books about "ecological footprint" at Amazon UK, USA and Canada
How about the footprint of Al Gore?   Was he telling the truth?
Statistician Nic Marks asks why we measure a nation's success by its productivity -- instead of by the happiness and well-being of its people. He introduces the Happy Planet Index, which tracks national well-being against resource use (because a happy life doesn't have to cost the earth).