Transcript 11b. Human Populatio..

Human Population Issues
Human Impact Model
I = PATS
• Models are simplified representations
of complex systems.
• Models can be precise or conceptual.
• This model is conceptual, to guide
your thinking about human impact and
sustainability.
I = PATS
• I is the impact of humans on the environment
• P is the population of humans in the affected
environment
• A is the affluence level of the human
population
• T is the technologies that the human
population is using
• S is the sensitivity of the environment to
human disturbance
Population
• Population growth is the root of many
environmental problems, although it is NOT
the only root.
• There is a carrying capacity for humans
based on environmental limitations
• Our technology has increased human
carrying capacity, but there have been other
consequences to these increases.
Human carrying capacity
Affluence
• Affluence means quality of life.
• In terms of environmental impact it is often
proportional to the amount of natural resources
that an individual (or country) uses.
• Higher affluence often correlates with higher
environmental impact
• The gap between rich and poor societies is a
cause of social and environmental stress
Consumption leads to waste
Rich vs. poor
Ecological Footprints
Technology what do you think?
• How does technology make human impact
greater?
• How can technology reduce human impact?
Sensitivity
• Sensitive environments are more affected
by a given amount of human activity
• Sensitive environments include deserts,
grasslands, and tundras
• Luckily, humans populations are not very
dense in these types of environments
Another representation…
• In Industrial Ecology, IPATS is couched as
the “Master Equation:”
Total Impact = Population *
GDP Environmental Impact
*
*S
person
unit GDP
• In this form we can see the opportunity for
improvement lies in the technology term,
environmental impact per unit GDP