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GEOG 1125 TEST #3 REVIEW
Energy Resources
Non-Renewable Resources – a resource with a fixed amount
Fossil Fuels: coal, oil, gas Coal – solid combustible mixture of organic compound (30-98% carbon) Who? U.S. – 24% U.S., China, and Russia – 66% How long? Identified reserves at current usage rate – 225 years Advantages: Ample supply, very high energy yield, low cost Disadvantages: Very high impact, land disturbance, threat to health, high CO2 emissions Crude oil – liquid composed of mostly hydrocarbon (refined for gasoline, fuel,…) Who? OPEC – 67% U.S. – 3% (uses 26%) How Long? Current usage rate: 25 billion barrels/year Identified reserves at current usage rate – 53 years Undiscovered oil may add 20-40 years Advantages: Low cost, high energy yield, low land use Disadvantages: Need to find substitute, pollution (high CO2 emissions) Natural gas – underground deposits of gas (50-90% methane) Who? U.S. – 3% Russia and Kazakhstan – 42% How much total: about 140 trillion cubic meters How long? Identified reserves at current usage rate – 200 years Undiscovered reserves may add up to 325 years Advantages: Ample supply, high energy yield, low cost, moderate impact Disadvantages: High CO2 emissions, difficult to transport Nuclear energy – energy released from nuclear fission or fusion Produces 6% of worlds commercial energy Produces 16% of electricity
Advantages: Large supply, low impact Disadvantages: High cost, low energy yield, radioactive waste, dangerous, spreads nuclear technology
Renewable resources – resources which can be replenished fairly rapidly
Reduce dependence on fossil fuels and reduce pollution Solar – direct radiant energy from the sun Advantages: Energy is free, no emissions, moderate costs, perpetual Disadvantages: Need access to sun, need storage system, low efficiency, high land use Hydropower – electrical power produced by flowing of water Supplies 6% of world’s commercial energy, 4% in U.S. Supplies 20% of world’s electricity, 10% in U.S. , 99% in Norway Advantages: Moderate to high energy yield, low-cost, perpetual, low CO2 emissions Disadvantages: High construction costs, high land impact Wind – electricity generated from wind power Supplies 18% of Denmark’s electricity Advantages: Moderate to high energy yield, high efficiency, moderate construction costs, low impact (no CO2 emissions) Disadvantages: Steady winds needed, high land usage Geothermal – heat transferred from underground Advantages: Very high efficiency, moderate energy yield, low land use, moderate impact Disadvantages: Scarcity of sites, may be depleted, moderate air pollution Biomass – (trees) Advantages: Renewable if harvested sustainably, large potential supply Disadvantages: Moderate to high impact, soil erosion, water and air pollution
Agricultural Resources
Soil Main agricultural resource Much of it is depleting due to: Soil Erosion – the movement of soil components by wind and water
Population growth still outpaces food production and distribution Many people (about 800 million) are undernourished 1 out of 5 people in the U.S. are suffer from over nutrition The world produces enough food, but it is not distributed evenly Solutions: Increase use of GMOs Better distribution systems Develop more marginal land by conservative farming methods Reduce soil erosion
Atmospheric Resources
Atmosphere – mixture of gases and liquid particles suspended in the air Constant Gases – found in same proportions within lower atmosphere; as altitude increases, percentages stay the same but amount decreases Nitrogen – 78% Oxygen – 21% Argon - .9% Variable Gases – gases that influence weather and life systems Carbon Dioxide – absorbs radiant energy Water Vapor – quite variable 4% by volume in tropics, <1% in deserts Source of clouds and precipitation Absorbs radiant energy Ozone – absorbs damaging UV radiation Concentrated in stratosphere (10-50 km above earth) <.00005% by volume Formation by splitting an O 2 molecule with shortwave radiation and combining with O atoms, forming O 3 (ozone) Ozone “Hole” Caused by CFCs found in coolants, aerosol cans, sterilants… UV radiation breaks apart CFC molecules and chlorine atoms react with O3 breaking it apart Primarily thinning in Antarctica (50%) and Arctic (11-38%) Ozone holes are largest in early spring 1% loss of O3 leads to 2% increases in UV radiation Consequences: Increased UV radiation at surface Increases cases of skin cancer and cataracts Increases damage to health Solutions: Stop using ozone-depleting chemicals Montreal Protocol agreement of 1987 was a step in this direction
Vertical Structure of the Atmosphere
Air Pressure – force exerted by the weight of a column of air above a given point Avg. at sea level is 1013 mb (1 kg above every cm^3 ) As altitude increases, pressure increases 50% atmosphere is below 5.6 km, 90% is below 16 km Temperature – measure of the degree of hotness or coldness of a substance (avg. molecular motion of an object) T is a function of pressure and volume T may increase or decrease with altitude Inversion – when T increases with altitude Temperature Lapse Rate – change in T with a change in altitude Layers of the atmosphere : 2 regions based on chemical composition: Homosphere – uniform chemical composition (from surface to 80-100 km) Heterosphere – changing chemical composition (above homosphere) 4 main later based on temperature: Troposphere – T usually decreases as altitude increases (surface to 12 km) Stratosphere – T stays constant or increases with altitude Contains ozone layer Mesosphere – T decreases with increasing altitude (about 50-80 km) Thermosphere – T increases dramatically with altitude (up to 1650 degrees F ) (above 80 km)
Climate Change: Evidence and Timing
Variations in climate may differ on different time scale Climate system – interaction of the atmosphere, lithosphere, biosphere, and hydrosphere; all are interconnected Evidence of climate change: sediment, oxygen isotope analysis, tree rings, palynology, geology, historical records Causes of climate change: Non-human causes: plate tectonics, volcanoes, solar variation, eccentricity, obliquity (deviation from the norm), precession (changes in orientation of earth’s axis), changes in ability of oceans to store CO2 and heat, ocean currents, sea leve, cloud cover Human induced causes: Greenhouse gasses - trap outgoing LW radiation and heats up the earth can lead to global warming since 1800, CO2 levels have increased 25% Global Warming Greenhouse Effect – LW radiation is bounced back and forth between the atmosphere, maintain temperature
