Human Population Issues

Human Impact ModelI = 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:”

• In this form we can see the opportunity for improvement lies in the technology term, environmental impact per unit GDP