1. The Human Factor
AP Env Sci

2. The Human Footprint

3. Human Factor
Excluding Antarctica and Greenland, Human activities have directly affected about 83% of the Earth’s land surface.
Where it is possible to grow corn, wheat, or maize – 98%!
Comparison of Natural and Human-Dominated Systems (Miller):
Property
Natural Systems
Human-Dominated Systems
Complexity
Biologically Diverse
Biologically Simplified
Energy Source(s)
Renewable Solar
Mostly Fossil Fuel
Waste Production
Little or None
High
Nutrients
Recycled
Often Lost/Wasted
Net Primary Productivity
Shared Among Many Species
Used, Destroyed, or Degraded

4. Some History: Three Revolutions
Neolithic Revolution: about years BCE
Development of animal husbandry and agriculture.
Requires permanent settlements and specialization of labor.
Reduced mortality  population growth
Industrial Revolution: 1st half 19th century
Modern science and technology
Increased production and commerce
Based on fossil fuels
More pollution
Increased population growth
Environmental Revolution: Coming? Here Now?

6. Altering Nature to Meet Human Needs & Wants
Reduction of biodiversity by destroying, fragmenting, and degrading wildlife habitats.
Reduction of biodiversity by simplifying and homogenizing natural ecosystems.
Use, waste, or destruction of an increasing percentage of Earth’s Net Primary Productivity that supports all Consumers.
Strengthening some populations of pest species and disease-causing bacteria.
Elimination of some predators.

7. Altering Nature to Meet Our Needs & Wants
Deliberate or accidental introduction of new or non-native species.
Overharvesting of renewable resources.
Interference with the normal chemical cycling and energy flows in ecosystems.
Increased dependence on non-renewable energy sources.