ABSTRACT

It is important to study and understand the complex relationships between the many changing factors that affect human ecological sustainability. These include, but are not limited to, human population P, freshwater supplies W, energy supplies E (including fossil fuels and renewable sources), food supplies F, natural resources N (metal ores, cement, wood, etc.), the economy [using gross domestic product (GDP) as a measure], emerging diseases D (human, animal, and plant), and pollution C (atmospheric: greenhouse gasses, volatile organic compounds (VOCs); water and land: insecticides, fertilizers, steroid hormones, bacteria, etc.). W, F, N, and C directly affect and are affected by ecosystems.