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Chapter 14 William P. Cunningham University of Minnesota Mary Ann Cunningham Vassar College Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 Geology and Earth Resources 2 Earth’s Cross Section 3 Tectonic Processes • Upper layer of mantle contains convection currents that break overlying crust into a mosaic of tectonic plates. Slide slowly across earth’s surface - Ocean basins form where continents crack and pull apart. - Magma (molten rock) forced up through the cracks forms new oceanic crust that piles up underwater in mid-ocean ridges. 4 Tectonic Plates 5 Tectonic Plate Movement 6 Pangaea 7 Rocks and Minerals • A mineral is a naturally occurring, inorganic, solid element or compound with a definite chemical composition and regular internal crystal structure. • A rock is a solid, cohesive, aggregate of one or more minerals. Each rock has a characteristic mixture of minerals, grain sizes, and ways in which the grains are held together. 8 Rock Types • Rock Cycle - cycle of creation, destruction, and metamorphosis Three major rock classifications: - Igneous - Sedimentary - Metamorphic 9 Rock Cycle 10 Cool Quick Cool Slow 11 Rock Types and Examples Igneous Solidified from magma extruded onto the surface from volcanic vents eg: Basalt (quick cool) Granite (slow cool) Metamorphic Change existing rock, heat, pressure Marble (from limestone) Quartzite (from sandstone) Slate (from mudstone and shale) Sedimentary Formed from deposits due to Weatherization and Sedimentation eg: shale, halite 12 Weathering and Sedimentation • • • Mechanical weathering – physical, no change chemical composition Chemical weathering - removal or alteration of specific components, weakens and disintegration Oxidation Hydrolysis Sedimentation - deposition of particles of rock transported by wind, water, ice and gravity until they come to rest in a new location 13 Coal • • • • What types of coal are there? What type of rock is it? Lignite, Bituminous, Anthracite Which type has the most energy? Which is Anthracite has the least sulfur content? (pollution) 14 15 16 17 Sedimentary Rock • The sedimentary rock of Bryce Canyon National Park has been carved by erosion into tall spires. 18 Geomorphology • • study of the processes that shape the earth’s surface and the structures they create. Humans shape the Earth’s surface more than any other single geomorphic process except plate tectonics. 19 Geologic Hazards • • • Asteroid impact wiped out dinosaurs. Floods take the greatest number of lives, while wind causes the most property damage. Earthquakes - sudden movements of the Earth’s crust that occur along faults where one rock mass slides past another Gradual movement - called creep or seismic slip - When friction prevents creep, stress builds up until eventually released with a sudden jerk. - Point at which first movement occurs is called the epicenter. 20 Earthquakes continued • • • • Worst death tolls from earthquake occur when construction is poor. Now buildings in earthquake zones are reinforced. Most seismically active region in U.S. is west coast, but largest earthquake recorded was in New Madrid, Missouri. Earthquakes followed by aftershocks Tsunami can be generated by earthquakes as we saw in 2004. WHY live in areas that are susceptible? U.S. has installed warning buoys in ocean. 21 Volcanoes • Volcanoes and undersea magma vents are the sources of most of the Earth’s crust. Many of world’s fertile soils are weathered volcanic material. 500 million people live in danger zones. WHY? Nuees ardentes - deadly clouds of hot gas and ash like those that destroyed Pompeii. Temperatures exceed 1000 degrees C. and they move at 60 mph. Kill in minutes. Mudslides often accompany eruptions. Volcanic dust and sulfur emissions reduce sunlight and temperature around the globe. 22 Excerpt from “Life Without Oil” by Steve Hallet and John Wright 23 Eruption of the Mayon Volcano in Philipines 24 Mt. Saint Helens, WA 25 Landslides • • Landslides are examples of mass wasting, in which geologic materials are moved downslope from one place to another. Can be slow and subtle or swift as in rockslides and avalanches HUMAN IMPACT Road construction, forest clearing, cultivation, and building on steep, unstable slopes increase the frequency and damage done by landslides. WHY? 26 Landslide in Pacific Palisades, California 27 Chapter 15 William P. Cunningham University of Minnesota Mary Ann Cunningham Vassar College Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 28 Air, Weather, and Climate 29 The Atmosphere is a Complex System • • • Weather – short-lived, local patterns temperature and precipitation. Climate – long term patterns of temperature and precipitation. The atmosphere is composed of: Nitrogen gas Oxygen gas Water vapor Aerosols-minute, suspended particles & droplets 31 36 38 39 Energy Balance 40 Absorbed vs. Reflected Solar Energy • Surfaces that reflect energy have a high albedo (reflectivity). Fresh clean snow 80-85% • Surfaces that absorb energy have low albedo. Dark soil 3% • Overall net average albedo of earth = 30% • Absorbed energy evaporates water and runs photosynthesis. Absorbed energy released as heat. 41 Energy and the Greenhouse Effect • Most solar energy reaching the Earth is near infrared (short wavelength). Energy reemitted by the earth is mainly far infrared radiation (long wavelength, heat) - Longer wavelengths are absorbed in the lower atmosphere, trapping heat close to the earth’s surface. Greenhouse Effect The atmosphere transmits sunlight while trapping heat. 42 Convection Currents 43 Weather 44 45 46 47 Climate 49 The Coriolis Effect Makes Winds Curve • As air warms at the equator, rises, and moves northward, it sinks and rises in several intermediate bands, forming circulation cells. Surface flows do not move straight north and south, but are deflected due to Coriolis effect. Winds and currents appear to move clockwise in Northern Hemisphere and counterclockwise in the Southern Hemisphere. These curving pattern results from the fact that the earth rotates in an eastward direction as winds move above it. 51 Circulation Patterns 52 Circulation Patterns 55 Jet Streams • Jet streams - hurricane force winds at the top of the trophosphere which follow an undulating path 57 Ocean Currents Modify Weather • Warm and cold ocean currents strongly influence climate conditions on land. As surface water moves, deep water wells up to replace it. - Ocean circulation also driven by differences in water density due to temperature and saltiness of water Gyres - huge cycling currents carrying water north and south Currents can shift abruptly. 58 Global Ocean Conveyor System 59 Billions of People Rely on Seasonal Rains • Monsoon - seasonal reversal of wind patterns caused by differential heating and cooling rates of oceans and continents Most prevalent in subtropical and tropical areas. Tilt of Earth’s axis changes location where the Sun is most intense over the course of the year. Places where the Sun shines most directly have evaporation and convection currents which bring thunderstorms. Seasonal rains support tropical forests and fill great rivers such as Ganges and Amazon. 60 Summer Monsoons in India 61 Cyclonic Storms • When rising air is laden with water vapor, latent energy released by condensation intensifies convection currents and draws up more warm air and water vapor. - Hurricanes (Atlantic) Katrina in 2005 caused greatest natural disaster in North American history. - Typhoons (Western Pacific) - Cyclones (Indian Ocean) 62 Cyclonic Storms • Tornadoes - swirling funnel clouds Generated by “supercell” frontal systems where strong dry cold fronts collide with warm humid air - Greater air temperature differences in the spring, thus more tornadoes 63 Cyclonic Storms 64 Hurricane Matthew Oct. 2016 65 Hurricane Matthew Oct. 2016 66 Natural Climate Variability • • Climates shift on scales of decades, centuries or millenia. Ice cores - collected from glaciers, have revolutionized our understanding of climate history. Cores reveal patterns of dark and light bands caused by annual accumulations of snow. Gas bubbles can be analyzed for atmospheric composition. Ash and sulfur deposits correlate with volcanic eruptions. Vostok ice core gives us a record back 420,000 years. 67 Multi-Decade Ocean/Atmosphere Cycles • • The ocean and the atmosphere have regular patterns of flow or currents, but these may shift from time to time. Winds and rains may change as a consequence of these shifts. Pacific Decadal Oscillation - very large pool of warm water moving back and forth across the North Pacific every 30 years. - This affects salmon harvests in Alaska and the Pacific Northwest. 68 El Nino Southern Oscillation (ENSO) Most years, the pool is held in western Pacific by steady equatorial trade winds. Surface waters driven westward by trade winds allow upwelling of cold, nutrient rich waters off west coast of South America benefiting fisheries. During intervening La Niña years, hot, dry weather is often present. Resulting high sea surface temperatures cause hurricanes to be more violent. Long term studies of coral reefs indicate that ENSO events are becoming stronger and more irregular due to global warming. 69 70 Multi-Decade Ocean/Atmosphere Cycles North Atlantic Oscillation, or NAO is another oscillation which occurs between Canada and Europe. - Evidence for this phenomenon can be seen in tree-ring growth records. 71 Historical Climate Changes • • • A historical climate change that had disastrous effects on human populations was the Little Ice Age that began in the 1400’s. Temperatures dropped, crops failed, fish migrations changed and shipping lanes were blocked with ice. Ice cores show drastic changes may have occurred over short periods of time (years or decades rather than centuries). 72 Earth’s Movements Explain Some Cycles Milankovitch Cycles - periodic shifts in Earth’s orbit and tilt which change distribution and intensity of sunlight. 73 Global Climate Change 74 Greenhouse Effect Greenhouse Gases -Gases in the atmosphere, especially carbon dioxide, water vapor, nitrous oxides, methane and other substances that retain heat. Positive feedback loop - poles covered with ice reflect solar radiation back into space. Now that ice is melting, open water is absorbing more heat, which in turn is melting more ice, leading to more warming. 75 Major Climatic Changes • The data show that: There is a close correlation between carbon dioxide concentration and temperature of the atmosphere Gradual climate changes give species time to adapt. Abrupt climatic changes have catastrophic effects on living things as organisms are unable to adjust before conditions exceed their tolerance limits. These changes can cause species extinctions. 76 Vostok Ice Core Data 77 Recent Changes are Unusually Rapid • • • • • Many scientists believe that anthropogenic climate change is the most important environmental issue of our time. The earliest data on came from an observatory on Mauna Loa volcano in 1957. Initial measurements showed carbon dioxide levels increasing at 0.5% per year since data collection began. Levels have risen from 315 ppm in 1958 to 387 ppm in 2009. If this trend continues, we could double atmospheric CO2 levels by 2109. 78 CO2 Measurements from Mauna Loa 79 The IPCC Provides Data to Policy Makers • • • Intergovernmental Panel on Climate Change or IPCC -an international group of scientists and governmental representatives formed to review the scientific evidence for climate change. The 2007 report stated that there is a 90% probability that the observed climate changes are the result of human activities. The report projects warming of 1-6 °C by 2100 with the best estimate being 2 to 4°C (3.2 to 7.8°F) For perspective, there has only been a 5°C rise since the last ice age 20,000 years ago. 80 Affects of Global Warming • • • • People will experience more extreme weather including droughts, floods, heat waves and hurricanes. These could have disastrous economic and human costs. Estimates published in 2009 project a sea level rise of 1 meter by 2100. This could flood low-lying coastal cities like New Orleans, Miami, Boston, New York and London and Mumbai. 81 Projected Sea Level Rises by 2100 82 LOOK AT ARTICLE SEA LEVEL COULD RISE 6 Meters 83 Climate Models vs. Observed Climate Change 85 CO2 is the Most Important Green House Gas • • • • Carbon Dioxide – emissions have increased 80% from 1970 to 2004 fossil-fuel burning is the major human caused source of carbon dioxide (constitutes 77%). Methane (CH4) – ruminants and rice paddies are sources - Absorbs more infrared than CO2 . Nitrous Oxide – vehicle engines, agriculture processes are major sources. - Highly effective at capturing heat energy. The relative effects of each green house gas can be seen by converting them to CO2 Equivalents. 86 Warming Ability of Various Green House Gases 87 Contributors to Global Warming 88 Climate Change Effects: Why Should I Care? • • • Evidence of climate change is overwhelming: “As best as can be determined, the world is now warmer than it has been at any point in the last two millennia, and, if current trends continue, by the end of the century it will likely be hotter than at any point in the last two million years.” American Geophysical Union 89 Observations of Climate Change • Ave. global temperature climbed 0.6°C (1°F) in last century. 19 of 20 warmest years in the past 150 yrs have occurred since 1980. Poles are warming fastest (4°C, 7°F over past 50 years). Permafrost is melting in Alaska and Canada and houses, pipelines and trees are being toppled. Obama Article and $100 billion dollar Article 90 Observations of Climate Change • • • • • Arctic Sea ice is half as thick as it was 30 years ago, and the ocean area covered by ice has decreased by 1 million sq. km. in 30 yr. Polar bears are dying as they hunt on pack ice, which is declining. Antarctic ice shelves are disappearing. Penguins declined 50% in last 50 yrs. Alpine glaciers are retreating all over the world. The oceans are absorbing and storing more heat. Sea level has risen 15 to 20 cm in last century. 91 Observations of Climate Change • • • • • Oceans are absorbing some of the extra CO2 but that is acidifying the ocean and damaging corals. Growing seasons are lengthening in Northern hemisphere. Some animals are breeding earlier or extending their range. Others are disappearing. Droughts are more frequent and widespread and storms more severe. Animals breeding and migratory schedules are changing. Some species are declining or going extinct due to warming temperatures and loss of habitat. 92 Observations of Climate Change • • Corals are bleaching due to warming water temperatures in the oceans. Storms are becoming stronger and more damaging. ie. Increased number of category 5 hurricanes in recent years. 93 Global Warming will be Expensive • • • At present, reducing greenhouse gas emissions would cost 1% of world GDP according to Stern report. (IPCC report says less than that.) If we delay, it could cost as much as 20% of world GDP. Energy production will need to be 80% decarbonized by 2050 to stabilize climate. Those in richer countries will be able to blunt the effects of climate change. Those in poorer countries will suffer the most; at least 200 million people in will become refugees of floods or victims of drought. 94 4 Steps For Combating Climate Change • • • • Implement emissions trading Technology sharing with less developed countries Reducing deforestation Helping poorer countries adapt to climate change 95 Flooding, Storms and Disease • • • Melting of the glacial ice caps in Greenland and Antarctica could raise global seal levels 100 meters flooding coastal areas where 1/3 of the world’s population live. Insurance companies have $2 trillion in insured properties along U.S. coastlines at risk from flooding or severe storms. Infectious diseases will increase as insects that spread them are able to move to places where they could not live before. 96 Envisioning Solutions • Kyoto Protocol (1997) Called on nations to roll back carbon dioxide, methane, and nitrous oxide emissions about 5% below 1990 levels by 2012. - Sets different limits for different countries, depending on prior output China and India were both exempt from this agreement. 126 countries ratified the Protocol. The legislatures of both Australia and the U.S. declined to ratify the agreement. 97 2 Main Options for Controlling Emissions • Cap and Trade Controls: legal limits on emissions are set and countries that want to emit more must purchase emissions credits from others. This approach is favored under Kyoto. • Voluntary Limits: governments, communities and individuals voluntarily cut emissions for altruistic, economic or conservation reasons. New local initiatives suggest this approach may work. 98 Cap and Trade • • • • A global market for trading carbon emissions has already developed. In 2006 700 million tons of carbon credits were exchanged with a value of 3.5 billion dollars. This market may grow to 500 billion dollars a year by 2050. Some large businesses like BP America, Dupont and GE are for this approach if the rules are clear and fairly applied. 99 Stabilization Wedges Could Work Now • • • • • By utilizing Wedge Analysis, the problem of climate stabilization can be broken down into smaller, bitesized peices. To stabilize carbon emissions we would need to cut 7 GT (gigatons) over the next 50 years. Doubling vehicle efficiency, and halving the miles we drive would save up to 1.5 GT. Installing energy efficient appliances, lighting and insulating building could save another 2 GT. Capturing and storing carbon emissions from power plants and gas wells could save another GT. 100 Carbon Capture and Storage 103 Should We Focus on Methane Instead? • • • • Methane is a more powerful absorber of heat energy than carbon dioxide. James Hansen of NASA believes that focusing on reducing methane emissions might be the best short-term strategy to slow global warming. Reducing methane emissions from landfills, rice paddies, oil wells and coal mines could reduce warming. Reducing the number of ruminants could help also. 104 Regional Initiatives Are Emerging • • • • The U.K., New Zealand, Germany and many other countries are working to reduce carbon emissions voluntarily. The United Kingdom has rolled back its CO2 emissions to 1990 levels and is aiming for a 60% reduction by 2050. New Zealand has pledged to be the first Carbon Neutral country-reducing green house gas emissions to zero. Germany has reduced CO2 by 10%. 105 Conservation and Renewable Energy Offer the Best Solutions • • • • Denmark gets 20% of its electricity from windmills, and plans to increase that to 50%. China reduced its emissions 20% between 1997 and 2005 by implementing more efficient burning of coal in power plants and industry. Individual cities like Copenhagen, Helsinki and Toronto have pledged to reduce carbon emissions by 20% by 2010. Benefits: Conservation efforts save energy costs and shifting to renewable energy frees us from dependence on foreign oil. 106 Chapter 17 William P. Cunningham University of Minnesota Mary Ann Cunningham Vassar College Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 107 Hydrologic Cycle 111 Average Annual Precipitation 112 Water Supplies are Unevenly Distributed • Three principal factors control global water deficits and surpluses: Global atmospheric circulation Proximity to water sources Topography Rain Shadow 113 Rain Shadow 114 Major Water Compartments • • The length of time water typically spends in a compartment is called the Residence Time. For example, the Average residence time of water in the ocean is about 3,000 years before the water evaporates and enters the hydrologic cycle. 116 The Oceans are a Major Water Compartment • • • The oceans hold 97% of all liquid water on the earth. 90% of the earth’s biomass is found in the oceans. The oceans play a major role in moderating earth’s climate. 117 Global Ocean Conveyor System 118 Easily Available Fresh Water is Scarce 119 Ground Water Compartments Ground water is the second largest reservoir of fresh water Infiltration - process of water percolating through the soil and into fractures and permeable rocks Zone of aeration - upper soil layers that hold both air and water Zone of saturation - lower soil layers where all spaces are filled with water Water table - top of zone of saturation 121 Infiltration 122 Groundwater Stores Large Water Resources • Aquifers - porous layers of sand, gravel, or rock lying below the water table Artesian - Pressurized aquifer intersects the surface (water flows without pumping). • Recharge zones - area where water infiltrates into an aquifer Recharge rate is often very slow. - Presently, groundwater is being removed faster than it can be replenished in many areas. 123 Groundwater 124 River & Streams Are Water Compartments • Rivers and Streams Precipitation that does not evaporate or infiltrate into the ground runs off the surface, back toward the sea. - Best measure of water volume carried by a river is discharge The amount of water that passes a fixed point in a given amount of time Usually expressed as cubic feet per second 125 Major Rivers of the World 126 Lakes and Ponds are Water Compartments • Lakes and Ponds Ponds are generally considered small bodies of water shallow enough for rooted plants to grow over most of the bottom. Lakes are inland depressions that hold standing fresh water year-round. - Both ponds and lakes will eventually fill with sediment, or be emptied by an outlet stream. 127 Wetlands are Water Compartments • Wetlands Play a vital role in hydrologic cycle - Lush plant growth stabilizes soil and retards surface runoff, allowing more aquifer infiltration. Disturbance reduces natural waterabsorbing capacity, resulting in floods and erosion in wet periods, and less water flow the rest of the year. Half of U.S. wetlands are gone. 128 The Atmosphere: A Small Water Compartment • The Atmosphere Among the smallest water reservoirs - Contains < 0.001% of total water supply - Has most rapid turnover rate - Provides mechanism for distributing fresh water over landmasses and replenishing terrestrial reservoirs 129 Water Availability and Use • Renewable Water Supplies Made up of surface runoff plus infiltration into accessible freshwater aquifers - About two-thirds of water carried in rivers and streams annually occurs in seasonal floods too large or violent to be stored effectively for human use. Readily accessible, renewable supplies are only about 400,000 gal /person/year. 130 Water Consumption Is Less Than Withdrawal • • Withdrawal - total amount of water taken from a source Consumption - fraction of withdrawn water made unavailable for other purposes (not returned to its source) Degradation - Change in water quality due to contamination making it unsuitable for desired use. Much water that is not consumed is nevertheless polluted. 133 Water Withdrawal and Consumption 135 Agricultural Is the Greatest Water Consumer • Worldwide, agriculture claims about two-thirds of total water withdrawal and 85% of consumption. Aral Sea, is a tragic example of this. The Aral Sea was once the fourth largest inland body of water in world, but it has now lost 80% of its volume since 1975 as the water was diverted for irrigation of rice and cotton crops. Lake Chad is another example. Located in northern Africa, this lake went from 400,000 sq. km to less than 1,000 sq. km. Show Google Maps of Midwest 137 Aral Sea 138 Figure 17_14a 140 Figure 17_14b 141 Figure 17_14c 142 Domestic and Industrial Water Use • • Worldwide, domestic water use accounts for about one-fifth of water withdrawals. Only about 10% of consumption - But where sewage treatment is unavailable, water is degraded Industry accounts for 20% of global freshwater withdrawals. Range from 5% to 70% in various locations - Small proportion is consumed, but degradation is a problem 143 Typical Household Water Use in U.S. 144 Freshwater Shortages • • • U.N. estimates a billion people lack access to safe drinking water. 2.6 billion lack acceptable sanitation. At least 50 countries, mostly in Africa and the Middle East, are considered to have serious water stress. In many countries it is not access to water that is a problem, it is access to clean water that is the problem. 145 Many People Lack Access to Clean Water • • • More the 2/3 of the world’s population lack indoor plumbing and must fetch water from outside the home. Where water is available in the home, it may be expensive. In Lima Peru, a typical poor family uses 1/6 as much water as a typical middle class family in the US and pays 3 times as much for the water and they must boil the water before it is safe to drink. By 2025, the U.N. estimates that 2/3 of the word’s population will be living in water stressed countries. 146 Groundwater is Being Depleted • • Groundwater is the source of nearly 40% of fresh water in the U.S. 50% of Americans (95% in rural areas)depend on groundwater for drinking and domestic uses. Heavy pumping can deplete entire aquifers. Ogallala Aquifer underlies 8 states between Texas and North Dakota. Heavy pumping has dried up wells and whole towns are being abandoned It will take thousands of years to refill. 147 The Ogallala Aquifer 148 Depleting Groundwater • Withdrawing large amounts of groundwater in a small area causes porous formations to collapse, resulting in subsidence (settling). Sinkholes form when an underground channel or cavern collapses. Results in permanent loss of aquifer. Saltwater intrusion can occur along coastlines where overuse of freshwater reservoirs draws the water table low enough to allow saltwater to intrude. 149 Saltwater Intrusion 150 Dams and Diversions • Before 1900 there were 250 high dams in the world; today there are more than 45,000. • In the U.S. dams are built by Army Corps of Engineers and Bureau of Reclamation Provide cheap hydroelectric power Jobs Reduce flooding Allow farming on lands that would otherwise be too dry 155 Dams and Diversions • On the downside, dams Drown free flowing rivers Submerge farmlands and towns Block fish migration e.g. salmon Change aquatic habitats for native species Can sometimes fail, causing catastrophe - Johnstown flood (city just east of Pittsburgh, PA) killed 2,200 people when dam broke. - Dam failure in China killed 230,000. 156 Figure 17_11 157 Would You Fight for Water? • • Nearly 40% of the world’s population live in river or lake basins that are shared by 2 or more countries. There have already been water skirmishes: Israel and its neighbors over the Jordan River. Turkey and Iraq over the Tigris and the Euphrates Rivers. Nomadic tribes in Kenya have fought over dwindling water resources. 160 Trans-boundary River Basins 161 Increasing Water Supplies • • Seeding Clouds Condensation nuclei Desalination - removing salt from ocean water or brackish water to get fresh water Most common methods are distillation and reverse osmosis. - Three to four times more expensive than most other sources 164 Domestic Conservation • Estimates suggest we could save as much as half of domestic water usage without change in lifestyle Largest domestic use is toilet flushing - Can use low volume toilets or waterless composting - Anaerobic digesters use bacteria to produce methane gas from waste Significant amounts of water can be reclaimed and recycled. Purified sewage effluent San Diego pumps water from sewage plant directly into drinking reservoir 165