Chapter 4 I.Energy Resources A.What are resources? 1.Diff types of resources a. Capital: $ or machines used to produce goods or svcs b. Human: people who perform tasks c. Natural: materials in the natural environment that people value & use to satisfy their needs 2. Nonrenewable Resources a. Cant be replaced a limited supply b. Minerals formed in earths crust over millions of yrs c. Ex: iron, gold, copper, oil d. Fossil Fuels: formed from remains of ancient plants/animals - Main energy source of industrialized countries!!! - Coal, oil, natural gas Fossil Fuels AdvantagesDisadvantagesFuture? Oil Natural Gas Coal 3. Nuclear Energy Produced by fission splitting of uranium atoms in a nuclear reactor, release stored energy ProsCons How nuclear power works 4. The problem of nonrenewable resources how can we prolong the inevitable? a. New technology to find more b. Recycle c. Reduce overall consumption - conserve d. Increase energy efficiency 6. Renewable Resources constantly regenerated or replaced by environment a. Examples: soil, forests, water, sun, wind b. Human activities can interfere with renewal - deforestation, oil spill etc c. Renewable energy sources AdvantagesDisadvantagesFuture? Wind Solar Water Geothermal Three Gorges Dam China Larry Hagman's Solar Ranch 7. Alternative Fuels? AdvantagesDisadvantagesComments? ethanol Alternatiave Fuel Comparison B. Energy Sources 1.Availability a. Few countries have sufficient supply - must import b. Oil/natural gas unevenly distributed over the world - over oil supply in SW Asia - lrg reserves of natural gas in Eurasia - coal is more evenly distributed but whats the problem? 2. Distribution of Resources a. Uneven distribution affects where people live, economic activities, trade networks b. Population centers develop near resources or near easy means of transportation c. When few resources available, people migrate to develop trade Population Living on Less Than US$2 per Day 2002 Percent Source: World Bank, World Development Indicators 2006. II. Water Resources A.Water on Earth our most precious resource! 1. Distribution a. 97% in oceans; 3% fresh - most fresh water tied up in glaciers b. Water Cycle - amt of water stays constant thanks to repeating cycle, but physical state changes : gas liquid solid Water Cycle 2. Surface Water a. Water flows from high to low - headwaters 1 st & smallest streams formed from the runoff of a mt, eventually forming rivers - tributaries small streams or rivers that flow into larger stream or river - watershed or drainage basin the entire region drained by a river and its tributaries b. Surface water may collect in lakes - lakes provide water supplies, fish, and recreation opportunities - lakes can also reduce severity of climate on their shores c. Lake salinity (saltiness) - may collect minerals from runoff - as water flows in & evaporates, mor minerals build up. Saltiness d. Estuaries semi-enclosed bodies of water, seawater, and freshwater formed where a river meets an inlet of the sea - mix of seawater/freshwater - make good harbors - rich in fish/shellfish - shelters for animals Estuaries e. Wetlands landscapes that are covered with water for at least part of a year - bogs, coastal marshes, wooded swamps - rich in fish, shellfish, birds, native plants - migrating birds depend on wetlands for food, water & rest - threatened by drainage projects (farmland, housing, industrial sites). Over US original wetlands destroyed - FL Everglades, Okavango delta in Africa The Florida Everglades Hippos in the Okavango Delta - Botswana Wetlands 3. Ground Water a. Water found below ground b. Plant roots reach down to absorb this water c. Water table the groundwater level at which all the cracks and spaces in rock are filled with water - rises/falls w/ rainy/dry season - excessive drop in water table (thanks to drought or irrigation) may lead to subsidence or sink holes d. Water Scarcity - see article in packet B.Floods 1. occur when rivers carry more water than stream channels can hold (heavy rain, snow melt) a. Erodes land b. Destroys vegetation c. Drown people/livestock d. Destroy crops e. Disrupt/destroy infrastructure 2. Human activity leads to increased flooding a. Vegetation cleared = increased surface runoff b. flooding if rainwater cant sink into soil c. flood damage increasing with population increase in flood plain - fertile farm land, water transport, waterpower, water supply III. Natural Resources A.Soil & Forests 1. Soil Building a. Rocky sediment + organinc matter b. Humus broken-down plant & animal matter in soil c. Minerals in soil depend on parent rock d. Soil formation is slow (up to 100s of yrs) e. Leaching the downward mvmt of minerals and humus in soils - cause by excessive rain - low fertility 2. Sustaining soil reserves a. Soil erosion can be controlled via contour plowing plowing fields across a hill rather than up and down a hill b. Crop rotation the practice of planting different crops in a field in alternating years can prevent soil exhaustion a condition in which soil has lost nutrients and becomes nearly useless for farming c. Soil salinization salt buildup in the soil can occur as salt is present in irrigation water B.Forests 1. protect soil from erosion, provide habitats for many species, provide useful products (wood, rubber, oils, medicines) 2. Deforestation destruction or loss of forests a. Rainforests being cleared at rapid rate - for wood, farmland, ranch land 3. Reforestation replanting of a forest programs are increasing in some areas Deforestation C.Air & Water 1. Air a. Threatened by pollution/acid rain - smog & acid rain are short term issues - increased greenhouse gas emissions contribute to global warming long term issue b. ozone layer can be damaged by pollution 2. Water a. Traditionally, aqueducts artificial channels for transporting water have carried water to dry areas b. Where groundwater is the only source of water, wells are dug to extract water from aquifers rock layers where groundwater is plentiful c. Areas with little rainfall might rely on fossil water groundwater that is not replenished by rain - nonrenewable form of water - found mostly in desert areas