The Human Factor AP Env Sci 2011-2012

The Human Footprint

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

Some History: Three Revolutions Neolithic Revolution: about 12000 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?

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.

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.