1. Human Carrying Capacity

2. Human Carrying Capacity
Carrying Capacity: The maximum number of a species or “load” that can be sustainably supported by a given area
Human carrying capacity is difficult to measure because…
We use a huge range of resources
We can substitute one resource for another if we run out
Resource use varies between individuals
We are capable of importing/shipping resources long distances
We are capable of developing new technologies

3. Can we change our own carrying capacity?
Ecocentrists
Reduce resource use
Drop off “the grid”
Solar panels, collect rain water, grow own food…
Technocentrists
Might argue that we will always be able to expand our carrying capacity
Technological innovations!!!
Use remaining oil more efficiently?
Does trade and technology really improve carrying capacity?
Some say yes!
Some say it only improves our ability to exploit resources more efficiently

4. Limits to the human carrying capacity
1798: Population 1 billion
Malthus: “The power of the population is infinitely greater than the power of the Earth to produce subsistence for man.”
1976: Population 3.5 billion
Ehrlich: Warned of “famines of unbelievable proportions” and that feeding 6 billion people would be totally impossible.
Today…
Everybody has been wrong so far…
But some feel that the famines in Africa are only the beginning…

5. Ecological Footprints
Idea and how to calculate first published in 1996
Ecological Footprint: The area of land and water required to support a defined human population at a given standard of living
A model
Used to estimate the demand a population puts on the environment
If the EF is greater than the land and water available, then that population is living unsustainably
Vary significantly from country to country and person to person
In 2012 it was calculated that the global EF of all humans is equal to 1.5 Earths…
We are in an ecological overshoot and have been since the 1970s

6. Global Ecological Footprints

7. Sharing is Caring
If every person got an equal amount of land, we would each have…
1.8 hectares (or 1.3 if you don’t count non productive marine areas)
How do you compare?