Humans in the Biosphere • Like all organisms, we humans participate in food webs and chemical cycles. • Among human activities that affect the biosphere are hunting and gathering, agriculture, industry, and urban development.
Humans in the Biosphere • By the end of the last ice-age – about 11,000 years ago – humans began the practice of farming, or agriculture • Monoculture, fertilizers, and the green revolution.
Industrial growth and urban development • Human society and its impact on the biosphere (Earth) were transformed by the industrial revolution (1800’s) • Dense human communities produce waste that must be disposed of. • Certain industrial processes pollute air water and soil.
Renewable and Nonrenewable resources • Environmental goods and services may be classified as either renewable or nonrenewable • Renewable resources: can regenerate if they are alive or can be replenished by biological cycles if they are non-living (abiotic), but they are not necessarily unlimited. “ex: freshwater” • Human activities can affect the quality and supply of renewable resources such as land, forests, fisheries, air, and fresh water. • Soil erosion? • Desertification?
Renewable and Nonrenewable resources • Nonrenewable resources: are those that cannot be replenished by natural processes • Fossil fuel • Coal • Oil • Natural gas • Nuclear energy???
Renewable and Nonrenewable resources • Deforestation • Overfishing (aquaculture) • Air resources (smog, pollutant, acid rain) • Freshwater resources
Biodiversity • Biodiversity is the sum total of the genetically based variety of all organisms in the biosphere • Biodiversity is one of Earth’s greatest natural resources. Species of many kinds have provided us with foods, industrial products, and medicines – including painkillers, antibiotics, heart drugs, antidepressants, and anticancer drugs
Biodiversity • Human activities can reduce biodiversity by altering habitats, hunting species to extinction, introducing toxic compounds into food webs, and introducing foreign species to new environments • Demand for wildlife products???
Pollution • DDT • Biological magnification??? • Chloroflorocarbons (CFC’s) & the ozone layer. • UV ~ skin cancer, phytoplankton?
Ozone Layer (O3) • Many scientists are concerned about the thinning of the OZONE layer.
How Populations Grow • Exponential growth • Bacteria • Humans • Logistic growth • Carrying capacity • Predator / Prey relationships • Human population