Unit 6 Human Environment Interaction Stress on the Earth’s Landscape

I. Alteration of Ecosystems From the beginning…fires, hunted, exterminated Ecosystem-ecological units consisting of self-regulating associations of living and nonliving natural elements

II. Environmental Stress A. Obvious Actions-cutting of forests, emission of pollutants B. Less Obvious Actions-burying of toxic wastes, dumping garbage, use of pesticides C. Concerns-future of water supplies, state of the atmosphere, climate change, desertification, deforestation, soil degradation, disposal of industrial wastes

The IPAT Equation What is the IPAT Equation, or I = P x A x T? One of the earliest attempts to describe the role of multiple factors in determining environmental degradation was the IPAT equation. It describes the multiplicative contribution of population (P), affluence (A) and technology (T) to environmental impact (I). Environmental impact (I) may be expressed in terms of resource depletion or waste accumulation; population (P) refers to the size of the human population; affluence (A) refers to the level of consumption by that population; and technology (T) refers to the processes used to obtain resources and transform them into useful goods and wastes. The formula was originally used to emphasize the contribution of a growing global population on the environment, at a time when world population was roughly half of what it is now. It continues to be used with reference to population policy.

Environmental Concerns

Water renewable resource, availability is not evenly distributed, most along equator a. distribution is sustained through hydrologic cycle b. aquifers-water-holding rocks/wells that distribute H20 Sign. 50x as much in aquifers as precipitation c. water shortages –Africa, S. California, Spain

California Water Issues 80% water used for irrigation Supply insufficient for population Colorado River flow diminishing

The Aral Sea Once the 4 th largest lake on earth. Water diverted for Soviet Union cotton irrigation upstream on the Amu Darya and Syr Darya Rivers. Watch the following video clip…

The Aral Sea

Politics and Water in the Middle East Israel has one of the lowest natural renewable water resources in the world ½ of water supply comes from areas outside of Israeli state Jordan River key source of water supply for Israel, along with aquifers beneath the West Bank Desalinization is one of the ways in which Israel attempts to meet water demand throughout the state Note: most water comes non-Israeli states

80% of China’s rivers are unfit for human contact. Aquatic life in these rivers is in decline.

40% of U.S. rivers, lakes, and streams are not fit for swimming, fishing, or drinking.

Global Atmospheric Issues The Ozone Hole Global Warming Acid Rain

The Greenhouse Effect A normal climatic warming effect caused by permitting incoming solar radiation but inhibiting outgoing terrestrial radiation. Three gases are the primary cause: Carbon Dioxide (CO 2 ) Methane (CH 4 ) Water Vapor (H 2 O) The effect is possible because outgoing earth radiation is of much longer wavelengths than incoming insulation.

Global Warming

The Global Warming Hypothesis Human-induced rise in CO 2 levels is causing unnatural warming of atmosphere. Likely effects: – Increased storminess – Rising sea level (.2-1 meter in 100 years – IPCC, 2001) – Loss of arable land (some areas hotter, others cooler) – Extinction of thousands of species – Loss of nearly all coral reef – Millions of climate refugees – Loss of Arctic sea ice during summer

Acid Rain Burning fossil fuels-emission of sulfur dioxide and nitrogen oxide Leads to acidification of lakes and streams, stunted growth of forests, loss of crops

The Land I. Deforestation-44% of tropical rainforests had been cut down in the 1980s; predictions that all rainforests will be gone in less than 90 years; second-growth forests uninhabitable by most animal species II. Soil Erosion-pressures on land to produce more; 37,000 acres lost each year to livestock, wind erosion, dry climate III. Waste Disposal-U.S. largest producer of solid waste (3.7 lbs./person/day); open vs. sanitary landfills; suitable land for landfills decreasing; toxic (chemicals) vs. radioactive (low vs. high radiation)

Loss of Biodiversity U.N.’s Environmental Program’s Global Diversity Assessment indicates 8% of plants, 5% of fish, 11% of birds, and 18% of the world’s mammal species are currently threatened. *Species on islands are particularly susceptible to extinction. Why?