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Chapter 12 Climate Change and Humans • MHR ICT OUTCOMES The Exploring Further item, in combination with the interview with expert David Phillips, presents an excellent opportunity for students to satisfy ICT Outcomes C.5.4.1, C.7.4.1, and F.2.4.7. UNIT 4 AN ISSUE TO ANALYZE PROOF OR CONSEQUENCES: ASSESSING CLIMATE CHANGE REPORTS Student Book Pages 476 TR 12-115 Implementing the Investigation • Explain the investigation to students, highlighting the perspective of each of the writers using an example. • Provide students with articles for analysis or allow students to use various methods (print and electronic resources) to locate articles. (As an alternative to print and electronic stories, students could analyze television or radio news stories.) • Allow students time to discuss the articles they have found and choose one to analyze. • To encourage more meaningful class discussion, have each group of students analyze an article from a different perspective. Purpose • Students find an article on a topic related to climate change, written from a specific point of view, and analyze the article and its biases. Investigation Wrap-up • Have students answer the Analyze questions based on their article. • Discuss Analyze questions in class or collect. Advance Preparation Analyze Answers • Students’ answers will vary. Answers should include complete references using a standard referencing format. In order to assess students’ responses, you may wish to use Assessment Rubric 15, Design Your Own Rubric. WHEN TO BEGIN 1 week before WHAT TO DO • Book computers with Internet access or search for articles/sources on each viewpoint for students to use. APPARATUS MATERIALS – computer(s) with Internet access – articles on particular aspects of climate change presented from a number of perspectives, or a variety of resources from which to find articles Time Required • 90 min - 45 min to search for the articles (individually) - 45 min to complete the analysis (as a group) HINTS &HELPS • Students may have difficulty finding articles from a variety of viewpoints. Consider providing a number of articles (one from each viewpoint) for students to choose from to simplify the investigation. ASSESSING STUDENT INVESTIGATION Exploring Further, p. 475 ICT OUTCOMES The Unit Issue to Analyze presents good opportunities for students to satisfy ICT Outcomes C.2.4.2, C.3.4.1, C.7.4.1, F.2.4.7, F.3.4.2, F.4.4.1, and F.4.4.3. UNIT 4 REVIEW ANSWERS Student Book Pages 478 Understanding Key Concepts 1. The differences between an open, closed, and isolated system are: An open system, such as a biome, exchanges both matter and energy with its surroundings; a closed system, such as Earth, LEARNING CONCEPTS/OUTCOMES ASSESSMENT OPTIONS – describe and evaluate the role of science in furthering the understanding of climate and climate change through international programs – describe the role of technology in measuring, modelling and interpreting climate and climate change – use library and electronic research tools to collect information – appreciate that scientific understanding evolves from the interaction of ideas involving people with different views and backgrounds – assess students’ class participation and ability to answer the research questions in the context of a class discussion TR 12-116 2. 3. 4. 5. 6. MHR • Unit 4 Energy Flow in Global Systems exchanges energy, but not matter with its surroundings; and an isolated system exchanges neither matter nor energy with its surroundings. Some scientists consider the universe itself to be the only truly isolated system The biosphere is the place where organisms are found. Parts of the lithosphere (land), hydrosphere (water in oceans, rivers, soil, organisms etc.), and atmosphere (air) also belong to the biosphere. Earth’s radiation budget is a temperature and energy balance maintained by the fact that Earth reflects as much energy into space as it absorbs from the Sun. It is important that Earth “balances” its radiation budget because if the output of energy to space were greater than the input of energy Earth receives from the Sun, the temperature on Earth would drop. Conversely, if the energy output from Earth were lower than the input of energy from the Sun, the temperature on Earth would rise. Increases and decreases in Earth’s average global temperature would affect climates, and therefore biomes throughout the world. The reason the lower atmosphere is warmer than the upper atmosphere is that visible light from solar radiation passes through the atmosphere without heating the atmosphere directly. Solar radiation reaching Earth’s surface does heat the lithosphere and hydrosphere, however, which re-radiate the energy from the Sun as infrared radiation (heat). Some of this infrared radiation is trapped by greenhouse gases in the atmosphere. The most common greenhouse gas in the atmosphere is carbon dioxide. Greenhouse gases have properties that allow them to absorb the energy of infrared radiation. This absorbed energy raises the temperature of the air. When the gases re-radiate the energy, some of it goes back to the ground. ASSESSING STUDENT INVESTIGATION Unit 4 An Issue to Analyze: Proof or Consequences: Assessing Climate Change Reports, p. 476–477 7. The characteristics of Earth’s motion responsible for the changing seasons are that it spins on a tilted axis as it orbits the Sun. Because of this tilt in Earth’s axis, the northern hemisphere is leaning toward the Sun during the summer. From March through September, the southern hemisphere is leaning toward the Sun and the solar energy is more concentrated making it summer in the southern hemisphere when it is winter in the northern hemisphere. 8. Weather represents the day-to-day temperature and precipitation, while climate is long-term trends in temperature and precipitation. 9. The relationship between the Sun’s rays and the three general climate zones is related to the angle at which the Sun’s rays hit the Earth and their concentration. In the tropical zone, at some location throughout the year, the Sun’s rays are perpendicular to Earth’s surface; the Sun’s rays are also concentrated over a smaller area than in the other climate zones, making average temperatures warmer in the tropical zone than in the other zones. In the temperate zones in both hemispheres, the Sun’s rays are never perpendicular to Earth’s surface, and since they are spread over a larger area, the climate is not as warm as in the tropical zone. Only 5% of the Sun’s energy reaches the polar zones (the coldest zones), since the Sun’s rays make such as small angle with the Earth in the polar zones that the rays are distributed over a relatively wide area. At some times during the year, the polar zones have 24 h of day light and 24 h of darkness. 10. The specific heat capacity (c) of a substance tells one how much heat in joules is required to raise the temperature of 1 g of the substance by 1ºC. 11. The large specific heat capacity of water means that large bodies of water have a moderating effect on the climate of a region near the water. It takes a rel- LEARNING CONCEPTS/OUTCOMES – assess, from a variety of perspectives, the risks and benefits of human activity, and its impact on the biosphere and the climate – use library and electronic research tools to collect information – select and integrate information from various sources or from several parts of the same source – identify and apply criteria for evaluating evidence and sources of information, including identifying bias – identify multiple perspectives that influence a science-related decision or issue – seek and apply evidence when evaluating alternative approaches to investigations, problems and issues ASSESSMENT OPTIONS – collect and evaluate Analyze answers using Assessment Rubric 15, Design Your Own Rubric – use Assessment Checklist 9, Investigating an Issue/Controversy – use Assessment Checklist 24, Using the Internet Unit 4 Energy Flow in Global Systems • MHR 12. 13. 14. 15. 16. 17. 18. atively large amount of heat energy to warm the water, which can therefore absorb heat from nearby land, without much change in temperature. During cold spells, when the water cools it emits heat energy, which warms the nearby land. Three mechanisms of heat transfer are radiation, conduction, and convection. Solar radiation warms Earth’s surface, which re-emits the energy as infrared radiation. As highly energized molecules from Earth’s surface collide with molecules in the air, the heat energy is conducted through the atmosphere. Air currents distribute the heat via convection. The name for the amount of energy that is needed to convert 1 mol of a substance from a liquid state into a gas is the heat of vaporization (Hvap). Because water has a much larger heat of fusion than most similar substances, the large amounts of ice and snow that melt in the spring will not heat up much, even though the weather is getting warmer. Most of the available heat energy will go towards melting the snow and ice. The amount of water that can remain in the vapour phase depends on the temperature. When water vapour in the air rises and cools, the temperature can go below the dew point - the temperature at which it begins to condense into liquid water. It is quite likely that the result will be rain or snow. The hydrologic cycle is the cycle of water on Earth. For example, precipitation from the atmosphere falls onto the land and bodies of water, where it may freeze, or be absorbed by soil, relocated by rivers and streams, or taken up by living organisms. Plants transpire large volumes of water, thereby returning it to the atmosphere. The hydrologic cycle transports thermal energy from one place to another by ocean currents, or when ice and snow melt, which releases thermal energy to the surroundings. Ocean currents carry huge amounts of water long distances around the world. Warm water, such as the Gulf Stream, can remain warm even after traveling across the Atlantic Ocean and past the British Isles and toward northern Europe. Since water has a very large specific heat capacity, it carries a large amount of thermal energy that can be (and is) released to the surroundings. The British Isles and northern Europe are much warmer than they would be in the absence of the Gulf Stream and the North Atlantic Drift. Cold ocean currents can have the opposite effect. Some deserts are found very close to the coast because of cool air that is descending, which gets warmed by compression. Since warmer air can contain more water vapour than cooler air, the percent humidity goes down. More water can evaporate. TR 12-117 19. During an El Niño, the prevailing winds reverse direction over the south pacific. The coast of Peru, which is normally a desert, experiences heavy rainfalls. Australia and Indonesia become dry. The widespread change in wind patterns affects the rest of the world to a lesser degree. The temperature in central and western Canada is usually warmer. California might have floods while Ethiopia has a drought. 20. If Earth was not spinning on its axis, the pattern of prevailing winds would be simplified: At the equator warm air would rise, move towards the poles until reaching 30º(N and S), where it would descend and move back towards the equator. Similarly convection currents between 30º(N and S) and 60º(N and S), and between 60º(N and S) and the poles would also determine the pattern of prevailing winds. Prevailing winds would be to the north or south. 21. In both hemispheres, the Coriolis effect causes prevailing westerlies between latitudes of 30º and 60º, and easterlies at other latitudes, because air just above Earth’s surface rotates at the same speed as Earth’s surface. Therefore air masses at the equator travel faster than air masses at 30º latitudes, which travel faster than air masses at 60º. As a result, air currents heading from 30º towards the equator continue to rotate more slowly and fall behind the speed of rotation of Earth’s surface. This creates westward blowing winds, called easterlies. The same process occurs between latitudes of 30º and the poles. Air currents travelling from latitudes of 30º out to 60º retain the greater rotational speed of Earth’s surface at 30º latitudes, and therefore veer to the east. Since these winds come from the west they are called westerlies. 22. Mountains affect climate through orographic precipitation and the rain shadow effect. On the windward side of a mountain range, there will be increased precipitation caused by adiabatic cooling while on the leeward side of the mountain, there is a rain shadow effect (decreased precipitation) caused by adiabatic warming. These changes in precipitation have an effect on climate. 23. Jets streams are extremely fast moving currents of air about 10–15 km above Earth’s surface. Jet streams form at the borders between cold and warm masses of air, because the colder, denser air pushes beneath the warmer air, which rises and picks up speed. 24. A climatograph displays average monthly temperature and total monthly precipitation data for a location. 25. A biome is a large area that experiences a consistent climate resulting in characteristic plant and animal species. TR 12-118 MHR • Unit 4 Energy Flow in Global Systems 26. The subsystems within a biome are the individual ecosystems, which are each made up of interacting populations of organisms and their abiotic environment. The location where an organism lives is called its habitat. 27. Four biomes found in Canada are the tundra, taiga, deciduous forest, and grassland. 28. With increasing altitude the temperature drops because warm air moving up a mountainside will encounter decreasing air pressure; this leads to the warm air expanding and cooling. As one moves farther away from the equator, the angle at which the Sun strikes Earth’s surface is smaller, spreading the same quantity of energy over a larger surface area. Earth’s surface therefore absorbs less heat energy as latitude increases. Altitude and latitude also affect precipitation patterns, but not as predictably as temperature. 29. Behavioural adaptations that allow animals to stay warm include migrating to warmer climates during the winter, shivering, increased activity, huddling together with others of the same species, sunning themselves, hibernating, building burrows or shelters, and, in the case of humans, using fires and machines. 30. Structural adaptations are the physical characteristics organisms have that allow them to survive in their habitats. Examples will vary, and may include animal or plant adaptations. For example, cold weather birds might have feathers on their feet and legs. 31. A biome is considered an open system because there is an exchange of both matter (e.g. water and organisms) and energy (e.g. thermal energy, incoming and reflected solar energy) across its boundaries. 32. There is considerable evidence of climate change found in fossils, ice core samples, tree rings, and in erosion and deposition. 33. Catastrophic events such as volcanic eruptions or a large asteroid or meteorite colliding with Earth could cause climate change by putting large amounts of dust and particulates into the atmosphere, creating a sooty, dusty, or smoggy cloud. The cloud might reflect or absorb solar radiation, causing temperatures on Earth to drop. However, this could be followed quickly by warming due to the build up of greenhouse gases. 34. In a positive feedback loop, the stimulus has an effect that causes an increase in the original change. For example, rising global temperatures could lead to a melting of the polar ice, effectively reducing the albedo of Earth’s surface, which would in turn cause temperatures to rise more. In a negative feedback loop, the stimulus has an effect that “turns off” the original change; this is how a thermostat operates. 35. A catastrophic event, such as a large volcanic eruption or a large meteorite hitting Earth, injects enormous amounts of dust and soot into the atmosphere, which can spread over much of the world. Such an event can cause a cooling of the atmosphere by reflecting sunlight back out into space. Not only is the air cooled, but also plants do not receive enough light to photosynthesize at a normal rate. A cool climate and a reduced amount of vegetation can cause a mass extinction because animals cannot maintain their optimal body temperature and they cannot find enough to eat. 36. An increased amount of water vapour in the atmosphere will absorb more infrared radiation from Earth’s surface and thus make the air warmer. The warmer temperatures cause even more water to evaporate. As the amount of water vapour builds up in the atmosphere, it continues to warm by absorbing infrared radiation. The warm temperatures cause condensation of the vapour and creates heavy cloud cover. The cloud cover reflects solar energy back into space and thus begins to cool the atmosphere. The final result was the opposite of the initial change and is thus called “negative” feedback. 37. Students may mention any of the following pieces of evidence for global warming: Records indicate that the average global temperature near Earth’s surface has increased by 0.6ºC in the past century; the temperature of the lower atmosphere has risen in the last 40 years; snow and ice cover has melted; the global average sea level has risen by 0.1–0.2 m. 38. The natural greenhouse effect is caused by carbon dioxide and water vapour in the air from natural sources. Those greenhouse gases absorb just enough infrared radiation to maintain a constant average global temperature that supports life. With no greenhouse gases, Earth would be too cold for life as we know it. The enhanced greenhouse effect is the addition of excessive amounts of carbon dioxide into the atmosphere by the combustion of fossil fuels and by the generation of methane in the atmosphere from sources created by humans. Artificial compounds such as CFCs are also greenhouse gases. The presence of these additional greenhouse gases in the atmosphere has the potential to raise the average global temperature enough to alter climate conditions around the world. 39. The main reason for the increase in the amount of carbon dioxide in the atmosphere is the advent of the Industrial Revolution and the increasing rate at which people are burning fossil fuels. 40. A carbon sink is an area, such as a forest, that removes and stores large amounts of carbon dioxide from the atmosphere. Other carbon sinks are deep oceans, limestone deposits in Earth’s crust, and fossil fuels. Unit 4 Energy Flow in Global Systems • MHR 41. Saying that “methane has a global warming potential 21 times that of carbon dioxide,” is a way of saying that methane can trap heat 21 times more efficiently than can carbon dioxide. 42. Deforestation can affect climate in several ways. When a forest burns or when organic matter decays as a result of exposing the forest floor through logging, large amounts of carbon dioxide are released into the atmosphere. The increase in atmospheric carbon dioxide could contribute to global warming. Deforestation may also lead to desertification of an area. Deforestation also removes the trees that consume carbon dioxide. 43. Some effects of global warming on humans and other animal species are: Melting of the polar ice would cause the polar bear’s habitat to shrink, therefore putting the polar bear at risk; the prairies could become even drier, which could lead to loss of arable lands through desertification; and the incidence of dangerously severe weather could increase. Any reasonable effect — positive or negative — is acceptable. 44. Climate change could affect a biome because it is the climate that determines the type of vegetation that can survive in a biome, and the vegetation and climate that determines the types of animals that live in a biome. One biome could be changed into a different biome. 45. Some ways in which global warming could be reduced are: decreasing the amount of carbon dioxide in the atmosphere by decreasing the use of fossil fuels, and by planting forests; decreasing the amount of methane released to the atmosphere by changing the diet of beef cattle or burning off methane released from garbage dumps; decreasing the amount of dinitrogen monoxide released into the atmosphere from burning wood and fossil fuels; banning the use of CFC’s; and, potentially, reducing photochemical smog. 46. Many glaciers around the world are receding. The melting in the summer is greater than the accumulation of ice and snow in the winter. These receding glaciers are a symptom of global warming. 47. The precautionary principle says: “In order to protect the environment, a precautionary approach shall be widely applied by states according to their capabilities. Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing costeffective measures to prevent environmental degradation.” Developing Skills 48. If climate change is gradual, plants will adapt over time through natural selection. As the temperature gets warmer and drier, individual species that are 49. 50. 51. 52. 53. 54. 55. TR 12-119 better able to survive these changes in climate will survive and produce more offspring with these traits. Over time, all of the species that survive will have these traits. If climate change is rapid, there is no time for natural selection to take place and many species that are not able to survive the altered conditions will become extinct. If a room is kept at 18°C in the summer when the outside temperature is 24°C, the air that enters the room will not be able to hold as much moisture as it contained when it was warmer. Water from the now cooler air will condense on objects in the room unless it is “dehumidified.” In the winter, the opposite is true. The cold air will have been dried out as its temperature lowered to –9°C. When that air enters the warm house and warms up, it will tend to absorb water from the objects in the house, drying them unless the air is humidified. A greenhouse gas is defined as one that traps heat and keeps it within the atmosphere for a longer period of time before allowing it to be re-released into space. Humid places in Canada, such as Montréal, don’t cool off at night due to the water vapour in the air, which retains the heat. Dry places like the Prairies do cool off at night due to the lack of water vapour in the air. Water vapour, therefore, classifies as a greenhouse gas. Climatology is the study of climates today. Climatology-related careers include hydrology (the study of water), meteorology (including many subgroups, such as the study of weather), paleoclimatology (the study of past climates), and forecasters (predicting weather and climate). Evidence of warming in Canada includes the measurable retreat of glaciers and the thinning of ice in the Arctic. Humans have adapted to the places they live by constructing houses with thick or insulated walls, small windows, and small doors to keep the heat in if they live in cold climates. In warm climates, they build houses that allow a breeze to flow freely. In areas with significant rain or snowfall, the roofs are slanted to allow the precipitation to slide off. They also adjust their clothing to match the climate. A greenhouse gas delays the solar energy that enters the atmosphere for a period of time before allowing it to be released back into space. By absorbing and radiating the heat, greenhouse gases keep Earth much warmer than it would be otherwise. Without the greenhouse effect, the average temperature on Earth would be much cooler than it is now, and much of Earth could not sustain life as we know it. They are both important, but for different reasons. The natural sources are important in maintaining Earth at a temperature that sustains life. The human sources must be carefully monitored as they MHR • Unit 4 Energy Flow in Global Systems Problem Solving/Applying 59. Plants and animals from other continents can survive in Alberta because similar temperature and precipitation patterns (biomes) are found in other places in the world. 60. The difference is that this climate change is predicted to be occurring at a much more rapid pace than previous natural climate change. Plants and animals cannot adapt to changing climate that quickly. 61. Southern Alberta is predicted to become more like a desert due to its position in Canada. The entire world will become warmer. The increase in temperature will lead to increased evaporation resulting in a drier climate. 62. Circulation of ocean waters is partly a result of different masses of water having different densities. Salt content and temperature affect the density of water, therefore, this type of circulation is called thermohaline circulation. If the density of ocean water in the North Atlantic were reduced by the diluting effect of increased rainfall and melting of the polar ice cap, this would be expected to disrupt thermohaline circulation. Since thermohaline circulation is partly responsible for bringing warm waters nearby Northern Europe, a disruption in this circulation system could mean cooler temperatures in Northern Europe. 63. Scientific inquiry contributes to the decision-making process by providing peer-reviewed ideas accompanied with a degree of certainty. 64. The precautionary principle is appropriate where there is a degree of scientific uncertainty accompanied by a considerable risk. The risk of climate change fits these criteria. 65. By riding a bicycle instead of driving a car, less fossil fuels are burned, which lowers the quantity of carbon dioxide, dinitrogen monoxide, and ozone produced. 66. Alberta is home to some of the richest fossil deposits in the world, including evidence of tropical plants, suggesting that our climate has changed dramatically over time. 67. Climatograph Precipitation (mm) Temperature (°C) 180 25 160 140 15 120 5 100 -5 80 60 Temperature (°C) are the cause of the enhanced greenhouse effect, which is thought to be leading to climate change. 56. The projected climate change resulting from the enhanced greenhouse effect is considered a problem for various reasons: It could potentially alter biomes and put the species that live there at risk; the pattern of ocean currents could be affected, which would alter weather patterns and affect aquatic biomes; it could result in an increase in severe weather; and it could change farmland into desert. 57. Scientists evaluate the accuracy of computer models of future climates by using the same model to project into the past. Using data from core samples, scientists can evaluate how close their modelling system came to predicting the climate of the past. If the model was accurate in predicting the past, it has a better of chance of being accurate in predicting the future. 58. Burning fossil fuels creates carbon dioxide in the process of combustion. By cutting down forests, carbon dioxide is added to the atmosphere in two ways. The trees that are no longer photosynthesizing do not remove any carbon dioxide from the atmosphere, and the decomposition of the remaining roots leads to additional carbon dioxide release. Precipitation (mm) TR 12-120 -15 40 -25 20 0 -35 J F M A M J J A S O N D (a) The warmest month is July. (b) 11 mm of precipitation falls in the driest month (August). (c) The growing season would begin in April (the first month above 5ºC) and end in October (the last month above 5ºC). (d) This location is likely found in a grassland biome since the total annual precipitation is fairly low (321 mm) and the average temperature is 8.5ºC. To be taiga, the level of precipitation would have to be significantly higher. 68. Biomes differ from each other with respect to average temperature, overall precipitation, types of animals and plants that inhabit the biome, the distribution of precipitation throughout the year, and the length of the growing season. 69. Given Mass of air, m = 500 kg = 5.00 × 105 g J } Specific heat capacity of dry air, c = 1.00 } g•°C Change of Temperature, DT = 22ºC Required Heat, Q Analysis Use Q = mcDT. Solve for Q. Solution Q = mcDT J })(22ºC) = (5.00 × 105 g)(1.00 } g• °C = 1.10 × 106 J Paraphrase It takes 1.10 × 106 J of energy to heat 500 kg of dry air by 22 ºC. Unit 4 Energy Flow in Global Systems • MHR 70. Given Mass of water, m = 35 kg = 3.5 × 104 g J } Specific heat capacity of water, c = 4.19 } g•°C 6 Heat, Q = 1.4 × 10 J Required Change of Temperature, DT Analysis Use Q = mcDT. Solve for DT. Solution Q = mcDT c } DT = }m Q J }) (3.5 × 104 g)(4.19 } g•°C = }}} 6 (1.4 × 10 J) = 0.10475 ºC < 0.10ºC Paraphrase When 1.4 × 106 J of energy are added to 35 kg of water, the temperature will rise 0.10 ºC. 71. Given Heat, Q = 5.2 MJ = 5.2 × 103 kJ kJ } Heat of fusion of water, Hfus = 6.01 } mol g } Molar mass of water = 18.02 } mol Required Mass of ice (water), m Analysis Use Q = nHfus. Solve for n.. Solution Q = nHfus Q } n=} H fus 5.2 × 103 kJ = }} kJ } 6.01 } mol = 865.2246256 mol m } n = }M m = nM 18.02 g } = 865.2246256 mol × } mol = 1.5591 × 104 g < 1.6 × 104 g Paraphrase If you added 5.2 MJ of energy to some ice, this would be enough to melt 1.6 × 104 g. 72. Given Mass of water, m = 175 kg = 175 000 g g } Molar mass of water = 18.02 } mol Canada. Sceptics will argue that Earth is in a natural warming phase of this interglacial period, and that Earth would be warming whether humans were burning fossil fuels or not. Some students may say that the evidence for human activity leading to an increase in global warming is more convincing given the correlation between the increase of human-generated greenhouse gases and the increase in temperature over the last 100 years. 74. Some students may argue that increased temperatures will allow Canadian farmers to grow different types of crops, and that increased carbon dioxide levels will promote crop growth. Others will argue that global warming would probably hurt Canada’s economy. Although it would be warmer, reducing our heating costs and making our summers warmer and more enjoyable, the heat would come at the price of severe weather and a much drier climate. The cost of tornadoes, both in dollar values and in human lives alone, might be too high a price to pay. Agriculture will be hurt by drought conditions. We would, in theory, be able to grow more crops with a longer growing season, but the lack of water and fairly poor soil might not support these new crops. 75. All of the small plants, shrubs, and animals would be under water, as would the basements and the lower part of the first floors of buildings. People and many of the animals could adapt to this situation by migrating to higher ground. People could also build structures that would float on the water or ones that would be above the water (on stilts). 76. Students’ organizers will vary, but may contain information included in the following web. H2O(g) m } Number of moles of water, n = }M m n = }M} 175 000 g = }} g } 18.02 } mol = 9711.431743 mol kJ } Heat of vaporization of water, Hvap = 40.65 } mol Required Heat, Q Analysis Use Q = nHvap. Solve for Q. Solution Q = nHvap kJ }) = (9711.431743 mol)(40.65 } mol = 394769.7003 kJ < 3.95 × 105 kJ Paraphrase It takes 3.95 × 105 kJ of energy in order for 175 kg of water at 100ºC to evaporate. 73. Scientists have been tracking an increase in temperature over the last 30 years, which matches with an increase in greenhouse gas concentration in the atmosphere. They have also noted glacial melting and have been tracking the retreat of some glaciers in TR 12-121 N2O(g) Respiration Transpiration Evaporation Forest and brush fires Lightning Fossil fuel combustion Nitrogen fixation in soil and water Agriculture Nylon O3(g) halocarbons Smog Atmosphere CO2(g) Forest and brush fires Respiration Fermentation Volcanoes Decay Fossil fuel combustion (cars, heating, power) Agriculture Deforestation Leakage from pipelines Refrigeration and air conditioning Solvents Spray can propellants Foaming agents CH4(g) Deposits in permafrost and ocean floors Fermentation in cows and termites Decomposition in landfills Ranching Biomass burning Rice cultivation Leakage from pipelines TR 12-122 MHR • Unit 4 Energy Flow in Global Systems 77. In Alberta, we would suffer severe drought due to the increase in temperature and changing wind patterns. This would lead to a water shortage. In the cities, our grass would die as would many other plants. We would be restricted in how much water we use to wash and cook, either by rationing or increasing the cost so people would conserve water. In rural areas, farming would be hurt by the lack of water. If irrigation costs became too high, farmers would abandon their crops, likely leading to desertification and a drastic downturn in the economy. Critical Thinking 78. If Earth were the size of the Moon, instead of a three-cell model for air circulation, Earth would probably have a simple convection current model where the air would circulate from the equator to the Poles. The Arctic would be much wetter with this model. If Earth were twice the size, perhaps it would follow a six-cell model for air circulation instead of a three-cell model. This would result in the Poles being even drier. 79. If global warming occurs to the extent predicted by the IPCC, many highly populated areas that are associated with agriculture will experience extensive drought. If this should happen, water will become a resource in high demand, as was oil during the late twentieth century. The present conflict over the water in the Colorado River is one that will be waged all over the world. 80. Climate projections into the next century are based on current data and computer simulations. A simulation must make many educated guesses to predict climate 100 years into the future. If any of those guesses are incorrect, the final outcome will be significantly different. The range in predictions accounts for potentially incorrect guesses. Even accounting for the inaccuracy of guessing, these predictions might be completely incorrect if greenhouse gas emissions change significantly from what is currently projected. 81. Students may argue that a reduction of over 25% is not realistic given the rate of increase in Canada’s population, the downturn in the economy, and with no inexpensive easy-to-implement alternative energy source likely to be available in the near future. If Canadians are willing to make major changes in their lifestyle (everyone takes the bus, creates significantly less garbage, uses alternative energy sources wherever possible), a drastic reduction could be achieved. The Kyoto Protocol allows for other mechanisms to “reduce” greenhouse gas emissions, which may make the target attainable (purchasing credits from other countries if coupled with some lifestyle changes.) 82. Students’ responses should note that, while extinctions have occurred naturally in the past, changes in biomes tended to occur slowly enough that some species could adapt to the changing conditions. Rapid changes in environments, such as predicted global warming trends as a result of human activities, do not give species a long enough period of time adapt, which could lead to mass extinction. 83. Answers will vary. Some possibilities are: Some crops are more greenhouse gas-friendly than others (rice contributes significantly to methane emissions) and by cultivating these “friendlier” crops, some emission reductions may be achieved. The methane that is produced could be effectively trapped with technology, which allows for cost recouping as the methane is used as an energy source. Genetically modified crops that increase crop yields without more land clearing might be a cost-effective way to produce food and minimize gaseous emissions. Wherever possible, land that has been abandoned should be reforested to restore the soil to its previous fertility and provide carbon dioxide sinks. 84. Albertans may seize the opportunity to help decrease greenhouse gases if changes do not cost more to raise cattle. Education programs on how to raise cattle and sheep without overgrazing the land (leading to desertification) and on low methaneproducing feed (as long as it is comparable in price) will provide farmers with the knowledge they need to help the environment. The government would be closer to achieving Kyoto targets by reducing emissions from agriculture, so could offer a tax break to farmers using low methane-producing feed (or conversely, increase the taxes on regular feeds). By educating the public on the amount of energy used in raising beef, individuals may choose to change their eating habits to consume less meat. Although this would, in the short term, decrease the profits of the ranchers, a growing population will continue to require beef. New technology that could trap the methane produced by cattle that would later be used as an energy source is another (albeit far-fetched) alternative. 85. Answers will vary but may include the following: Large boulders can be used to cover the soil and protect it from the wind; “sand fences” can be used to keep the sand from spreading; placing straw grids around an area will decrease the speed of wind, and vegetation can be planted in this sheltered area; if irrigation is an option, dunes can be stabilized by growing shrubs on the windward side, and, after high speed winds level off the tops of the dunes, trees can be planted there. All of these initiatives require some money and labour. There are also technological issues. Unit 4 Energy Flow in Global Systems • MHR Although the building of sand fences is technologically simple, providing irrigation is not. Environmentally and politically, restoring land is a positive move as it will help restore economic and social stability to a nation. The cultural issues would vary country to country; however, most countries view efforts to restore and prevent further destruction to be utmost in importance. 86. Answers will vary, although students should note that in the twenty-first century, should the IPCC’s predictions hold true, Alberta will become much drier and warmer, and other parts of Canada will be much wetter. In Alberta, skiing and skating may not be available. We might have to travel to the Yukon or Northwest Territories to ski. Crop farming may no longer be possible in Alberta, or, perhaps different types of crop would be grown. Sheep and cattle ranches may be impossible to sustain, so farmers may raise desert-adapted livestock, or stop farming in Alberta. If water is rationed, swimming may also be a pastime that we will no longer enjoy. Having a bath may be a luxury that most families will not be able to afford, and we may take a two-minute showers only once per week. TR 12-123