* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Science and Technology
Economics of global warming wikipedia , lookup
Climate change in Tuvalu wikipedia , lookup
Climate sensitivity wikipedia , lookup
Climate change and agriculture wikipedia , lookup
Climate engineering wikipedia , lookup
Effects of global warming on humans wikipedia , lookup
Effects of global warming on human health wikipedia , lookup
Media coverage of global warming wikipedia , lookup
Low-carbon economy wikipedia , lookup
General circulation model wikipedia , lookup
Climate change mitigation wikipedia , lookup
Climate change and poverty wikipedia , lookup
Climatic Research Unit documents wikipedia , lookup
Global warming controversy wikipedia , lookup
North Report wikipedia , lookup
Climate change, industry and society wikipedia , lookup
Surveys of scientists' views on climate change wikipedia , lookup
Scientific opinion on climate change wikipedia , lookup
Fred Singer wikipedia , lookup
United Nations Framework Convention on Climate Change wikipedia , lookup
Climate change in the United States wikipedia , lookup
Effects of global warming on Australia wikipedia , lookup
Physical impacts of climate change wikipedia , lookup
Attribution of recent climate change wikipedia , lookup
Global warming hiatus wikipedia , lookup
Mitigation of global warming in Australia wikipedia , lookup
Global Energy and Water Cycle Experiment wikipedia , lookup
Public opinion on global warming wikipedia , lookup
Years of Living Dangerously wikipedia , lookup
Global warming wikipedia , lookup
Politics of global warming wikipedia , lookup
Solar radiation management wikipedia , lookup
Instrumental temperature record wikipedia , lookup
Trial Version Science and Technology The Nature and Development of Science and Technology Case study – The important issues of science and technology Case 5: Global Warming Activity and case-based learning & teaching resources Students’ version Table of Content (Students’ version) Outline Aims of study Scheme of work Background information Teaching Resources Lesson 1, 2 Background Activity 1: Case analysis Activity 2: Drafted proposal on measuring the average temperature at school Additional background information Extended activities 2 2 3 4 4 4–7 8 9 10 Lesson 3, 4 Background Activity 3: Science experiments Additional background information Extended activities 11 11 11- 15 16- 19 20 Lesson 5, 6 Background Activity 4: Case discussion Activity 5: Reporting Additional background information 21 21 21- 23 24 25- 26 1 Students’ version Outline Aims of study The aim of these lessons is to introduce an important scientific issue – global warming – to students. Students are led to realise the existence of global warming and understand its causes and effects, so as to make self-reflections on the individual and social responsibilities. The lessons would emphasize case study and analysis to enhance students’ abilities of thinking and critical judgement of the problems. Through different group activities, students are encouraged to exchange their ideas, help them to understand the constraints of scientific investigations and build up the correct attitudes when exploring scientific evidences. Scheme of work Lessons Learning objective 1, 2 3, 4 5, 6 Teaching strategy What is global warming? Is global warming really occurring? How to measure the average temperatures of the earth? Build up the attitude of critical thinking toward different scientific explanations. What are the causes of global warming? The relationship between greenhouse effect and global warming. Science experiments What are the influences of global warming to us? Movie watching How do individuals and societies face and solve the problem of global warming? Learning and teaching resources Case analysis Links of articles Group discussion (the PowerPoint validity of global Worksheet of case warming) analysis Drafting a proposal Draft proposal on measuring the average temperature at school Experimental simulation of greenhouse effect on the earth Experiment discussion (the causes of greenhouse effect) Movie watching Case discussion (the Kyoto Protocol) Group discussion and oral reporting (how to face and solve the problem of global warming) Worksheet of the experiment PowerPoint Links of articles Worksheet on case discussion Assessment guidelines of oral reporting Links of articles 2 Students’ version Background information In the recent years, do you have a feeling that it is not as cold as before in winter and it is much hotter in summer than the past? What is happening actually? Let us investigate on the phenomenon of global warming. Firstly we have to raise a question – Is the temperature on the Earth rising continually? Some scientists use satellites to observe, to understand and to analyse the climatic changes on the Earth, and they recognise that the Earth is becoming warmer. Some scientists have an opposing idea to it since evidences show that the temperature of the Earth has been risen and dropped in the last 100 years, they claim that temperature increases within a short period is simply a natural phenomenon. Which statement is correct? Are there any data supporting it? Is temperature increase a natural phenomenon or human made? What is its relationship with the phenomenon as the ‘greenhouse effect’? Solar radiation can supply light and heat on the Earth, 30% of its radiation energy is reflected by clouds and the atmosphere and 70% is absorbed by the Earth surface. Part of the heat energy reached the Earth surface then leaves the Earth in the form of infrared radiation. The atmosphere absorbs the remaining part of the energy, which causes the air in the Earth become hot. The hot air would then radiate in all directions with part of the energy reflected back to the Earth surface. The continually circulating heat energy makes the earth become warmer and the phenomenon is called ‘the greenhouse effect’. The gases, such as carbon dioxide that absorb the radiation, are called ‘greenhouse gases’. The atmosphere is acting like the glasses of the greenhouses to trap the heat of the gases for maintaining a suitable temperature, which allows people to live comfortably. However, we need to concern when the amount of greenhouse gases exceeded the natural level, they will become a calamity causing global warming. Actually, carbon dioxide is released through respiration process of human and animals. But the intensive consumption of fossil fuels (such as crude oil, coal or natural gases) adversely affects the global level of greenhouse gases the most. According to the report of the Intergovernmental Panel on Climate Change- IPCC, the problem of global warming is more serious than we expected, as crisis will come if it is not dealt with as soon as possible. The consequences brought about by the climatic change would profoundly influence us. Melting of icebergs would submerge the cities, and natural disasters would halt the agricultural productions, etc. With the rapid expansion of population and fast technological development made recently, people have exploited the natural resources excessively for pursuing a better living environment. It accelerates the expansion of the scope of negative effects and causes unpredictable damages to the natural environment. The seriousness of the problem is clear. In order to minimize the damages to the nature caused by people, what can we do as an individual or a society? The lessons would be focused on a case study and analysis to enhance students’ abilities of thinking and critical judgement of the problem. Through reading, explanation, analysis and evaluation on the information about global scientific discoveries and technological inventions, students can evaluate the reliability of the situation claimed and understand the spirit of scientific investigation. Moreover, students should actively take part in different group activities to exchange their ideas with other students and teacher for complementation and exploring the domains of new knowledge. 4 Students’ version Teaching Resources Lesson 1, 2: Is global warming occurring? Background Do you realise that the weather has been changed greatly in the recent years? In Hong Kong, the winter has become much warmer in some days, the summer has arrived earlier and become hotter and the number of warm days has increased too. What are the reasons behind? Do the same situation occur all over the world? According to the record from the Global Temperature Logger, the last 10 years in the 20th century are included in the warmest 15 years from the middle of the 19th century, with 6 years having the highest recorded temperature. The situation is unusual in the past. What will the climate be in the coming 100 years or 1000 years then? Actually, the climate and seasons of the Earth are affected by the solar radiation. The regional climatic characteristics are depended on the amount of solar radiation received. Moreover, some natural phenomenon such as El Niño and volcano eruption would lead to short term climatic fluctuation and cause abnormal climates such as having the warmer or colder winter. As a result, we cannot claim that global warming is happening according to the fact of higher temperatures in the recent years only. In the long term, we still need to do more researches, observations and data collection to prove whether the climatic trend is warming. The name of global warming is obtained from observations. The atmosphere closer to the Earth surface become warmer that occurs without any signs. Its seriousness is unpredictable too. The phenomenon of warming is one of the various climatic changes which scientists have proved its happening in earlier time. How do the scientists make these conclusions? What kinds of experiments have to be carried out? How to analyse the data? The rise of temperature would bring about impacts and influences on people’s activities. For examples: Where can we live? What kinds of crops can we grow? Where should we grow? Where are the places that the organisms (such as pests) reproduce rapidly? Do we have to confirm the occurrence of global warming before preventing these hidden impacts? If it does occur, what are the extent and reasons of global warming? Activity 1: Case study The issue of global warming is concerned by different organisations and mass media worldwide and it is not difficult for us to see the related reports in our daily lives. We can have a look on the news and information worldwide first, and analyse the problems related to warming from the reports and cases. Students should judge whether the global warming is a real situation or not. Please read the case below: 5 Students’ version Case 1. Greenpeace marks CLP's 'unhappy' birthday for the climate (Extract) http://www.greenpeace.org/china/en/press/releases/greenpeace-marks-clp-s-unhapp January 25, 2005 Hong Kong, China — Greenpeace descended on the Kowloon headquarters of China Light & Power (CLP) today, to mark its 104th anniversary and over a century of environmental pollution. The green group declared the occasion an "unhappy birthday" for Earth's climate after naming and shaming CLP's coal burning operations all across Asia as a major contributor to climate change. Three volunteers then removed their T-shirts to reveal the slogan: "Stop Global Warming" painted on their bodies. Gloria Chang, Greenpeace Climate & Energy campaigner presented a birthday card to CLP, calling on the company to halt its planned expansion in coal power and to invest in clean renewable energy instead. Gloria Chang said: "Today is a sad day for the climate as it marks 104 years of CLP's climate crimes. Burning coal destroys our climate. CLP must take responsibility for over a century of causing climate change and stop investing in coal power now." Gloria Chang continued: "Climate change is happening now: the world is getting hotter and hotter, and we are already paying the social and economic cost. The World Health Organization says Climate change is already killing over 150,000 people each year and it's going to get much worse unless companies like CLP clean up their act. CLP must halt its investments in new coal projects and urgently invest in clean, renewable energy instead." Case 2. Global warming could be twice as bad as feared (Extract) http://www.spacedaily.com/2005/050126182825.zf2d1n9e.html 26 January, 2005 Global warming may be twice as bad as expected, according to a new assessment of a commonly-used yardstick of possible carbon dioxide (CO2) pollution. Until now, most computer models of climate change predict that if atmospheric levels of CO2 reach double of the pre-industrial age, the Earth's surface temperature will be between two and five C (3.6-9.0 F) warmer when compared with 1990 levels. But a study published Thursday in the British science journal Nature suggests that the temperature rise could be much higher -- of between nearly two (3.6 F) and more than 11 C (19.8 F). The research comes from a highly ambitious project in "shared computing," in which more than 90,000 people in more than 140 countries downloaded a special programme to crunch through data on their personal computer. 6 Students’ version The gas hangs in the atmosphere, trapping heat from the Sun that otherwise would radiate safely back into space. Scientists say this unbridled pollution is bound to have an effect on the world's delicately-balanced climate system. Their big challenge, though, is to figure out when, where and how the effects will kick in, and if the change will be gradual or if there will be a "tipping point" beyond which change will be cataclysmic. While there are many uncertainties, recent evidence suggests that carbon pollution is worsening faster than thought and that the first signs of climate change are already visible, in the form of extreme weather events such as recurrent El Ninos, droughts, floods and storms. Try to answer the questions below: 1. According to case 1, what are the purposes of the actions of the members of Greenpeace for the campaign? ___________________________________________________________________________ ___________________________________________________________________________ 2. Can you suggest some kinds of renewable energy production method that can be used by CLP? ___________________________________________________________________________ ___________________________________________________________________________ 3. According to case 2, what kinds of information about global warming were discovered? ___________________________________________________________________________ ___________________________________________________________________________ 4. What are the expected consequences on the Earth due to global warming? ___________________________________________________________________________ ___________________________________________________________________________ 5. According to what you have observed in the daily life, what kinds of information have proved the occurrence of global warming? ___________________________________________________________________________ ___________________________________________________________________________ 7 Students’ version 6. Do the information reliable? ___________________________________________________________________________ ___________________________________________________________________________ 7. What kinds of discovery do scientists make about the climatic changes recently? Have you ever heard of your parents talking about the difference of climates in the past and the present? ___________________________________________________________________________ ___________________________________________________________________________ 8 Students’ version Activity 2: Drafting a proposal on measuring the average temperature at school To do scientific researches, primarily scientists have to raise questions about the incidents and carry out further investigations to obtain the final conclusion. While they are conducting experiments and collecting information, the first thing they have to prepare is finding the ways to measure the information. The accuracy and reliability of information is extremely important during researches. The researchers have to notice any uncertainties that may affect the results including natural and human factors. Finally, the conclusion is made after detailed information analysis. For the problem of global warming, scientists have to find out the ways to measure the average temperature of the Earth. What are the most reliable and accurate ways for measurement? Now, teacher will divide students into groups of 4 to 5 people to simulate the work of scientists – measuring average temperature. So a proposal for measuring the average temperature at school would be drafted with detailed procedures. The content of proposal: 1. Aims: _________________________________________________________________________ _________________________________________________________________________ 2. Procedures: Hints:iii) Which kind of apparatus should be used for measurement? iii) Where should the apparatus be placed? iii) How many days should the measurement be taken for and how many times should it be taken daily? iv) How to analyse the information after collecting the data? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Analysis: _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Questions to think: After finished the proposal, do you think it is difficult to measure the average temperature? Is the information accurate? What are the factors affecting the results of measurement? Would the obtained data be questioned by others? 9 Students’ version Additional background information: What are the evidences proving that global warming is occurring? According to a report from the Intergovernmental Panel on Climate Change (IPCC), the global average temperature has increased for about 0.8℃ from 13.5℃ to 14.4℃ during the last 140 years. However, the change is not absolutely one-sided. The surface temperature of the Earth has been increased rapidly since 100 years ago. The first warming period is from 1910 to1945, which is then followed by another cold period for 30 years. Since 1976, the temperature has been increased continually until now and we are at a temperature-increasing trend at the moment (see Figure 1). In the same way, the measured horizontal height of seawater is also fluctuating. The monitoring stations at Amsterdam and Bucharest show that the average water level of seawater has increased for 130 mm in the last 100 years too. How do scientists measure the information needed? Due to the technological development, many countries worldwide have their observatories to measure and monitor changes in weather or using satellites to do so. To know the average temperature of a country or of the Earth’s surface, scientists can easily obtain various information. However, special monitoring stations are needed for measuring sea level and the composition of substances in the air (such as the Mauna Loa Observatory in Hawaii). For measuring the area and thickness of ice coverage at the North and South Poles, direct measurement is needed in addition to rely on satellites. The US Navy has sent submarines to measure the depth of sea ice in 1950s and 1990s. The depth was about 3.1 ft in 1950s and about 1.8 ft in 1990s. The significant drop of 42% showed the thickness of ice layer is reducing continuously. Changes in average temperature in ℃(1860 – 2000) 0.8 0.8 0.4 0.4 0.0 0.0 -0.4 -0.4 -0.8 -0.8 1860 1880 1900 1920 1940 1960 1980 2000 Figure 1 10 Students’ version Extended activity: Measuring regional temperature Although the area of Hong Kong is about 1000 km2 only, the pollution densities and geographical environment are different and so the temperatures are not necessarily the same. The temperature differences between urban districts and the New Territories are significant. In cloudless winter night and day with weak wind, open areas have a greater range of temperature drop than urban areas. The significant temperature drop is due to the fast heat-dissipating rate of the ground as air cannot keep the heat energy. The phenomenon is similar to a hot drink not covered by a lid, which would cool down more quickly. As a result, the temperatures in some regions in the New Territories (such as Lau Fou Shan, Da Kwu Ling) would be lower than urban areas for 5 to 6℃ or even 10℃ . Students can try to measure the indoor temperature of their home and draw a trend line for analysis and compare with other students. Extended questions (students should find out the answer by themselves) 1. How reliable are the temperature and the height of sea level simulated by computers? 2. What is the information used by scientists as the basis for computer simulation? 3. How can scientists know the weather conditions in 100 years ago? 11 Students’ version Lesson 3, 4: What are the causes of global warming? Background The function of solar radiation is supplying light and heat to the Earth and allows energy to be trapped in the Earth surface by the ‘greenhouse effect’. The greenhouse gases in the atmosphere (such as carbon dioxide and methane) act like glasses of the greenhouse to trap the heat energy from the sun. Students should bear in mind that the greenhouse gases construct a warm and comfortable living environment for us and provide a place of ease and comfort to human and animals. Owing to the presence of the atmosphere, the average temperature of the Earth is comfortable at around 15℃ now and not at the freezing -18℃. The difference in temperature is due to the greenhouse gases, which absorbs infrared radiation to affect the overall energy balance of the Earth. Using the moon as an example, without the protection of the atmospheres, the heat energy cannot be trapped. It leads to big temperature differences between day and night and make it unsuitable for humans to live in. Another problem of our concern relates to the amount of greenhouse gases, if they exceed the natural level, calamity will be caused. As more heat energy is trapped in the Earth, global warming is resulted. The atmosphere is composed of different gases and only about 1% of them are greenhouse gases generated from the natural world. In fact, carbon dioxide is released through the respiration process of humans and animals, which is the law of living organisms. Global warming is a major concern of lots of scientists even though they have different opinions. Some scientists believed that people are accelerating this process. People’s activities for improving their living quality would increase the global amount of greenhouse gases for the most. After the Industrial Revolution, people use machines for mass production and develop new technologies. The excessive consumption of fossil fuels used by cars and factories (such as crude oil, coal and natural gases) produce gases causing global warming. Furthermore, the intensive farming on agricultural lands and excessively cutting down trees in the forests also cause the natural world losing balance. The increase of greenhouse gases continually leads to temperature increase. However, some scientists have different viewpoints: the cause of global warming is from the natural world itself. The controversy provides us rooms for thoughts. It is important to have different ideas in science as it allows us to determine what to do next. That leads to the progression of the society. Should we change our present lifestyle to stop driving private cars and give up the luxurious lifestyles? Maybe we can make changes so that the nature can return to the normal cycles. In the lessons, students may think about the concepts and causes of global warming and investigate further the supporting evidences of the different viewpoints stated above. Activity 3: Science experiment The function of solar radiation is supplying light and heat to the Earth and allows energy to be trapped in the Earth surface by the ‘greenhouse effect’. The greenhouse gases in the atmosphere (such as carbon dioxide and methane) act like glasses of the greenhouse to trap the heat energy from the sun. Students should bear in mind that the greenhouse gases construct a warm and comfortable living environment for us and provide a place of ease and comfort to humans and animals. Using the moon as an example, without the protection of the atmospheres, the heat energy cannot be trapped. It leads to big temperature differences between day and night and makes it unsuitable for humans to live in. Another problem of our concern relates to the calamity caused by the amount of greenhouse gases exceeded the natural 12 Students’ version level. As more heat energy is trapped in the Earth, global warming is resulted. In fact, carbon dioxide is released through the respiration process of humans and animals, which is the law of living organisms. The most influential factors affecting the amount of greenhouse gases are peoples’ activities to enhance their living quality included the use of machines and development of new technologies. The excessive consumption of fossil fuels used by cars and factories (such as crude oil, coal and natural gases) produce gases causing global warming. Furthermore, the intensive farming on agricultural lands and excessively cutting down trees in the forests, etc. are also the causes. 1. Objective In the activity, students will become young scientists. Students have to act like scientists using verification method by setting up experiments for simulating the greenhouse effect of the Earth. You will understand the greenhouse effect, investigate the phenomenon of global warming and evaluate the accuracy of the experiment. 2. Theory The sun is the origin of a large amount of heat energy. This kind of heat energy can travel through the space through radiation. When the radiation hits on an object, such as the Earth, the object would warm up after absorbing energy. The warmed object will then emit energy to the space by radiation. The greenhouse gases in the atmosphere, such as the water vapour and carbon dioxide would absorb some of the radiation emitted from the Earth. When the atmosphere becomes warm, the heat energy will be radiated back to the Earth. The Earth absorbs the energy and becomes warmer. The alternation of radiation occurs continuously. 3. Materials(each group) 2 two-litre transparent soft drink plastic bottles 2 thermometers 2 colour pens 1 piece of 20"x20" cling film 1 100-watt light bulb 1 piece of wooden block for fixing the position of the lamp (if necessary) 3 pieces of thin cardboard 1"x 2" 4 cups of soil 1 medium-sized rubber band Adhesive tape Desk lamp without shelter 4 pieces of graph paper (with 1/4" grids) 13 Students’ version Cut to open the transparent plastic bottle Wooden block Bottle covered by cling film with rubber band Thermometer Thin cardboard Light bulb Soil Soil Thermometer placed inside the bottle Thin cardboard The set-up of experiment on greenhouse effect 4. Experiment procedure a. Use the wooden block to fix the light bulb. Test if all light bulbs function well. b. Use adhesive tape to stick the thermometers and cardboards inside the bottles. The anterior part on the thermometers should face outside (the markings can be seen) and thermometers should be far away from the light source. This point is very important. c. Put 2 cups of soil into each bottle. d. Cover one of the bottles with cling film and rubber band. e. Place the bottles at a distance of 2 inches beside the light bulb. Measure the space with 1" x 2" cardboards. f. Predict what will happen. g. Record the temperature of the bottles before switching on the light bulbs. h. During the next 30 minutes, record the temperatures of the bottles every 2 minutes. i. Switch off the light bulb and record the temperatures of the bottles in the next 6 minutes. j. Collect the data and present the result in graph. k. Add a title to the graph and use suitable measurement units. 14 Students’ version Information recording sheet Observed results Time(minutes) Temperatures of the opened bottle (oC) Temperatures of the closed bottle (oC) Graph Opened bottle Temp Cling film wrapped bottle Time 15 Students’ version Analysis and explanation 1. Why does the temperature rise? __________________________________________________________________________ 2. Why does the temperature reach equilibrium? __________________________________________________________________________ 3. Which bottle has the highest temperature increase? __________________________________________________________________________ 4. Why does the closed bottle need a higher temperature for reaching equilibrium than the opened bottle? __________________________________________________________________________ __________________________________________________________________________ Practical application(Extra questions) 1. How can your model represents the greenhouse effect? __________________________________________________________________________ __________________________________________________________________________ 2. Why is it important to record the temperature of the box after switching off the light? __________________________________________________________________________ __________________________________________________________________________ 3. What are the expected consequences if air pollution continues to worsen? __________________________________________________________________________ __________________________________________________________________________ 4. If this model is regarded as too simple, how to improve the model design? __________________________________________________________________________ __________________________________________________________________________ 16 Students’ version Additional background information: What is the main cause of global warming? There are many causes of global warming including natural and human factors. For natural factors, some people suspect that the sun has released more energy. However, scientific evidences have rejected the idea. Scientists have measured the amount of solar radiation received by the Earth and discovered that the amount of radiation emitted by the sun has not been changed greatly before they draw their conclusions. Scientists think that there are several natural factors causing global warming: (a) The distance between the Sun and the Earth has been changed that leads to increase or decrease of the radiation reaching the Earth. (b) The problem of the amount of black spot. Some scientists think that when the amount of black spot increased, the amount of radiation increased as well. But this point cannot be proved by satellite measurement. (c) The plate tectonic movement and the change of the landscape induce volcano eruption and cause temperature decrease in the short-term. There are two human factors, the first is the changes in atmospheric composition and the second is the change in shape and appearance of landscape. The expanding population and the rapid development of technology are also keys affecting the human factors. In about 1000 years ago, the world population was only about 600 millions and it was about 1 billion even in 1900. Nowadays, the world population reaches 6 billions already under a tremendous growth rate. It is estimated that another 5 billions will add on the population in the coming 200 years, which means the population will be 11 billions at that time. The more people, the more resources needed and the use of cars and industrial fossil fuels will be increased too. These are the major factors leading to the increase of greenhouse gases. Moreover, the overuse of lands, intensive farming of agricultural land and excessive cutting of trees in primeval forests, all lead to lose of balance in the natural world. The natural cycle of climate is interfered by human factors that leads to global warming as well. What is Greenhouse Effect? The “Greenhouse Effect” is a term that refers to a physical property of the Earth's atmosphere. If the Earth had no atmosphere, its average surface temperature would be very low of about -18℃ rather than the comfortable 15℃ found today. The difference in temperature is due to a suite of gases called greenhouse gases, which affect the overall energy balance of the Earth's system by absorbing infrared radiation. In its existing state, the Earth-atmosphere system balances absorption of solar radiation by emission of infrared radiation to space (Fig. 1). Due to greenhouse gases, the atmosphere absorbs more infrared energy than it radiates back to space, resulting in a net warming of the Earth-atmosphere system and of surface temperature. This is the “Natural Greenhouse Effect”. With more greenhouse gases released to the atmosphere due to human activity, more infrared radiation will be reflected back to the Earth's surface, which contributes to the “Enhanced Greenhouse Effect”. 17 Students’ version Fig. 1 A simplified diagram illustrating the global long-term radiative balance of the atmosphere. Net input of solar radiation (240 Wm-2) must be balanced by net output of infrared radiation. About a third (103 Wm-2) of incoming solar radiation is reflected and the remainder is mostly absorbed by the surface. Outgoing infrared radiation is absorbed by greenhouse gases and by clouds keeping the surface about 33℃ warmer than it would otherwise be. Types of Greenhouse gases Greenhouse gases comprise less than 1% of the atmosphere. Their levels are determined by a balance between “sources” and “sinks”. Sources and sinks are processes that generate and destroy greenhouse gases respectively. Human affects greenhouse gas levels by introducing new sources or by interfering with natural sinks activity. The major greenhouse gases in the atmosphere are carbon dioxide (CO2), methane, (CH4), nitrous oxide (N2O), chlorofluorocarbons (CFCs) and ozone (O3). Atmospheric water vapour (H2O) also affects significantly the natural greenhouse effect but it is thought that its presence is not directly influenced by human activity. Characteristics of some of the greenhouse gases are shown in Table 1. 18 Students’ version Trends in greenhouse gas concentrations a) Carbon Dioxide (CO2) High-quality observations of the concentration of CO2 began in 1958, with flask measurements at the Mauna Loa Observatory in Hawaii. Fig. 2 shows that the average annual concentration of CO2 in the atmosphere has risen from about 315 ppmv (part per million by volume) in 1958 to around 363 ppmv in 1997. There is a clear annual cycle in the Mauna Loa data that corresponds to the annual cycle of plant respiration in the Northern Hemisphere: CO2 concentration increases during the Fall and Winter and reduces during the Spring and Summer. This cycle, follows the growth and withering of vegetation, but is reversed and of smaller amplitude in the Southern Hemisphere, and this phenomenon cannot be observed from the data measured near the Equator. Fig. 2 Atmospheric carbon dioxide monthly mean mixing ratios. Data prior to May 1974 are from the Scripps Institution of Oceanography (‧ ), data since May 1974 are from the U.S. National Oceanic and Atmospheric Administration (‧ ). A long term trend curve (— ) is fitted to the monthly mean values. b) Methane (CH4) The rate of increase of the atmospheric abundance of methane has declined over the last decade, dramatically lowered between 1991 to 1992, though with an apparent increase in the growth rate in late 1993 (Fig. 3). The average trend over 1980 to 1990 is about 13 ppbv (part per billion by volume) annually. 19 Students’ version Fig. 3 Atmospheric methane mixing ratios from discrete air samples collected at Mauna Loa, Hawaii. A smooth curve (red) and long term trend (green) are fitted to the measurements (blue). Table 1: Characteristics of some major greenhouse gases Greenhouse gas Sources Sinks Importance for climate Carbon Dioxide (CO2) 1) Burning of fossil fuel 2) Land-use change (deforestation) 1) Ocean Uptake 2) Plants’ photosynthesis Absorbs infrared radiation; affects stratospheric O3 Methane (CH4) 1) Biomass burning 2) Enteric fermentation 3)Rice paddies 1) Reactions with OH 2) Microorganisms uptake by soils Absorbs infrared radiation; affects tropospheric O3 and OH; affects stratospheric O3 and H2O; produces CO2 Nitrous Oxide (N2O) 1) Biomass burning 2) Fossil-fuel combustion 3) Fertilizers 1) Removal by soils 2) Stratospheric photolysis and reaction with O Absorbs infrared radiation; affects stratospheric O3 Ozone (O3) Photochemical reactions involving O2 Catalytic chemical reactions involving NOx, ClOx and HOx species. Absorbs ultraviolet and infrared radiation Carbon Monoxide (CO) 1) Plant emissions 2) Man-made release (transport, industrial) 1) Soil uptake 2) Reactions with OH Affects stratospheric O3 and OH cycles; produces CO2 Chlorofluorocarbons (CFCs) Industrial production Insignificant in troposphere, dissociated in stratosphere (photolysis and reaction with O) Absorbs infrared radiation; affects stratospheric O3 1) Volcanoes 2) Coal and Biomass burning 1) Dry and wet deposition 2) Reactions with OH Forms aerosols, which scatter solar radiation Sulphur Dioxide (SO2) Source: Hong Kong Observatory http://www.weather.gov.hk/wxinfo/climat/greenhs/e_grnhse.htm <The article is edited by Education Bureau, Curriculum Development Institute (Science Education Section)> 20 Students’ version Extended activities: According to the theory of scientists, the larger amount of greenhouse gases, the higher heat absorption capacity it has. Is the theory accurate? Does the amount of greenhouse gases have direct effect on the temperature? Students can modify the science experiment done before to verify it by them. The suggested modifications are listed below: 1. Place plants in the simulated greenhouse Plants have the function to balance the ecosystem on the Earth. They will absorb carbon dioxide and release oxygen to balance the gas content. We can place a small pot of plant into the uncovered simulated greenhouse, and than cover it by cling film without changing other settings to repeat the experiment done before. Since the plant would absorb carbon dioxide, we can predict that the effect of greenhouse would be slightly weaker than normal and the temperature would be lower as a result. 2. Change the air by the gas we breathe out When air is breathed in our body, gas exchange occurs to release excess carbon dioxide from the body. As a result, the carbon dioxide content in the air we breathe out would be higher than normal air. We can use the uncovered simulated greenhouse, cover it by cling film without changing other settings after adding the air we breathe out for the experiment. Since the carbon dioxide content of the air we breathe out is higher than normal air, we can predict that the effect of greenhouse would be slightly stronger than normal. As a result , the temperature would be higher. 21 Students’ version Lesson 5, 6: What are the influences of global warming to us? Background Accompanying with the rapid population growth and the advances of technology, people are continually striving for more living spaces to seek for better living environment. The excessively use of resources has brought the impact on climatic change. Another calamity of the climatic change in time may create profound influences inducing such as the reduction of area of forest, the pollution of the Earth, water sources and air, and ozone layer depletion, etc. Other natural disasters such as flooding, drought and typhoon may also be caused. Global warming is an extremely serious problem, which influences people and the natural environment greatly. Although scientists continually predict the temperature changes in the future and simulated by computers, they still cannot accurately predict the results owing to the uncertainties exist. What we can confirm is that it would become crises for people in the future if the condition were kept worsening. Now it is the time for people to make decision about our future and we must change our livings. From the social and individual aspects, what kind of actions can we take for it? We should try to reduce the emission of greenhouse gases by all means as most of the greenhouse gases are produced in our daily life. For example, even vehicles, air conditioners and electricity are all necessities, we can try using them wisely: travelling more by public transport vehicles, a few persons with one car rather than driving individually, remember to switch off all the electrical appliances to save energy, etc. Can you suggest more ideas to make the Earth become a better place to live? We should recognise that: it is a mutual responsibility for all nations to construct a pleasant society and protect the global environment. All nations can legislate to regulate the greenhouse gases emission level of factories and electric power stations, invest on the resources for developing environmental saving energies and sign international treaties to constrict the greenhouse gases emission level of each nation. These are what people can do and also what people should do too. Activity 4: Case discussion Accompanying with the rapid population growth and the advances of technology, people are continually striving for more living spaces to seek for better living environment. The crisis of global warming is on the verge of breaking out. If it is not solved earlier, the crisis caused by the climatic changes will influence us greatly: individual health, drinking water sources, natural ecological environment, melting of icebergs, flooding of coastal lowlands, etc. So we could not ignore it. To reduce the negative influence of people to the natural environment, what can we do individually and socially? 22 Students’ version Study the case below: The Kyoto Protocol The Second Conference Of The Parties (COP-2) to the U.N. Framework Convention On Climate Change (FCCC) wrapped up in Geneva on July 19, 1996 as one hundred and thirty four governments adopted a Ministerial Declaration that committed themselves to the negotiation of "legally binding" greenhouse gas targets aimed at "substantial overall" reductions for industrialized countries by the end of 1997. They also said that the continued increase in greenhouse gas concentrations would lead to "dangerous" climate change. The Ministerial Declaration resulted from a positive step forward by the United States, which after years of obstruction, called for legally binding targets. The Ministerial Declaration's significance is that it calls for "legally binding" emission obligations for "significant overall" emission reductions. This provides very strong direction to the final stage of the Berlin Mandate and lead up to the Third Conference of the Parties (COP-3) in Kyoto, Japan in 1997. http://archive.greenpeace.org/climate/cop2/ Delegates to the various subsidiary bodies of the UN Framework Convention on Climate Change met in Bonn, Germany, in February and March 1997 to formulate proposals for a protocol or other legal instrument intended to be adopted at the Third Session of the Conference of the Parties to be held in Kyoto, Japan, 110 December. The discussions centered mainly on timetables and targets for emission reductions, the issue of coordinated versus flexible policies, whether different developed countries should have different targets or not, and the implications for developing countries. The ad hoc Group on the Berlin Mandate (AGBM) met in Berlin from 3 to 7 March 1997 to discuss future reductions in greenhouse-gas emissions by developed countries. During the talks, the European Union challenged other countries to a 15 per cent cut in emissions by the year 2010, compared with 1990 levels. http://www.wmo.ch/web/catalogue/New%20HTML/frame/engfil/wcn/preview.html The Third Conference of the Parties (COP-3) to the United Nations Framework Convention on Climate Change (FCCC) was held from 1 - 11 December 1997 in Kyoto, Japan. Over 10,000 participants, including representatives from governments, intergovernmental organizations, NGOs and the press, attended the Conference, which included a high-level segment featuring statements from over 125 ministers. Following a week and a half of intense formal and informal negotiations, including a session on the final evening that lasted into the following day, Parties to the FCCC adopted the Kyoto Protocol on 11 December. In the Kyoto Protocol, Parties in Annex I of the FCCC agreed to commitments with a view to reducing their overall emissions of six greenhouse gases (GHGs) by at least 5% below 1990 levels between 2008 and 2012 (Annex B lists quantified emission limitation or reduction commitments for Annex I Parties, which range from an 8% decrease to a 10% increase of GHG emissions from 1990 levels to be reached in a period between 2008 and 2012. The EU countries are to reduce GHG emissions from 1990 levels by 8%, the US by 7%, Japan by 6%, while countries like Australia and Iceland are allowed increases by 8% and 10%, respectively. The Russian Federation is to maintain its emissions at 1990 levels). The protocol also establishes emissions trading, joint implementation between developed countries, and a "clean development mechanism" to encourage joint emissions reduction projects between developed and developing countries. http://www.iisd.ca/vol12/enb1276e.html 23 Students’ version In 2001, the president of the United States stated to give up the support to the Kyoto Protocol with the reason that they were suspicious on the accuracy of the scientific information. However, the United States claimed that they would seek out other methods from researches to prevent the happening of global warming. The United State has agreed to follow the protocol that reduces the exhaust emission by 7%. However, they disagreed with the fact that developing countries included China and India were not included in the area of regulations. The United State believed that it would ruin their economies. N.B. COP-2 is the Second Conference of Parties to the U.N. Framework Convention On Climate Change (FCCC), COP-3 is the Third Conference of Parties to the U.N. F.C.C.C. Students need to answer the questions below: 1. Why did the Kyoto Protocol need to be established? 2. What is the content of the Kyoto Protocol? Is this method effective? 3. Why did the United States refuse the protocol finally? (Would China accept the Kyoto Protocol? Why?) 4. What is the role of Hong Kong in the issue? 5. What should the responsibilities of the society be undertaken for solving the problem of global warming? 6. What can individuals do to solve the problem of global warming? 24 Students’ version Activity 5: Oral Reporting After reading the article about the Kyoto Protocol, students should recognise that the international society has already taken actions to prevent global warming from occurring continually. In addition to establishing some international laws, are there any other solutions to solve the problem? What can we do individually? What can be done socially? Students are now divided into groups of 4 to 5 to think about the solutions together. A 5 minutes oral reporting has to be performed by each group. Some points to note: 1. More understanding on the topic 2. Collect information and detailed analyse in detail 3. Sharing of duties 4. Supporting resources Teacher can consider the items below as assessment criteria: Item Topic Content Related topics and the key points illustrated Evidence and information Appropriately quote and provide evidence and information Analysis Clear and logical analysis Structure Well-organized structure Presentation Clear and effective presentation Collaboration Collaborating among groupmates Contents of discussion and reporting: - The extent, seriousness, speed and location of global warming - What are the other solutions to tackle the problem other than establishing laws - What can be done individually? - What can be done socially? 25 Students’ version Additional background information: Consequences of Enhanced Greenhouse Effect 1) Global Warming Increase of greenhouse gases concentration causes a reduction in outgoing infrared radiation, thus the Earth's climate must change somehow to restore the balance between the absorption and release of radiation. This “climatic change” will include a “global warming” of the Earth's surface and the lower atmosphere as warming up is the simplest way for the climate to release of the extra energy to space through radiation. However, a small rise in temperature will induce many other changes, for example, cloud cover and wind patterns. Some of these changes may act to enhance the warming (positive feedbacks), others to counteract it (negative feedbacks). Using complex climate models, the "Intergovernmental Panel on Climate Change" in their third assessment report has forecasted that the global mean surface temperature will rise by 1.4℃ to 5.8℃ by the end of 2100. This projection takes into account the cooling effects of air particulates in the atmosphere on the Earth’s climate as well as the delaying effects of the oceans, which have a large thermal capacity. However, there are many uncertainties associated with this projection such as future emission rates of greenhouse gases, feedbacks on climate, and the magnitude of the ocean delay effect...etc. 2) Sea Level Rise If global warming really takes place, sea level will rise due to two different processes. Firstly, warmer temperature causes sea level to rise due to the thermal expansion of seawater. Secondly, water from melting glaciers and the ice sheets of Greenland and the Antarctica would also add water to the ocean. It is predicted that the Earth's average sea level will rise by 0.09 to 0.88 m between 1990 and 2100. Potential Impact on human life 1) Economic Impact Over half of the human population lives within 100 kilometers of the coast. Most of this population lives in urban areas near the harbours. A measurable rise in sea level will have a severe economic impact on low-lying coastal areas and islands, for examples, increasing the beach erosion rates along coastlines, rising sea level displacing fresh groundwater for a substantial distance inland. 2) Agricultural Impact Experiments have shown that with higher concentrations of CO2, plants can grow bigger and faster. However, the effect of global warming may affect the general atmospheric circulation and thus altering the global precipitation pattern as well as changing the soil moisture contents in all continents. Since it is unclear how global warming will affect the local or regional climate, the probable effects on the vegetation remains uncertain. 3) Effects on Aquatic systems The loss of coastal wetlands could certainly reduce fish populations, especially shellfish. Increased salinity in estuaries could reduce the species and amount in the 26 Students’ version freshwater but could increase the number of marine species. However, the full impact on marine ecology is not known. 4) Effects on Hydrological Cycle Global precipitation is likely to increase. However, it is not known how regional rainfall patterns will change. Some regions may have more rainfalls, while others may have less. Furthermore, higher temperatures would probably increase evaporation. These changes would probably create new pressure on the use of water resources. 5) Effects on Forests The sudden changes in weather would decrease the species richness of trees due to failure of adapting abnormal climate and shortage of water sources. The forest areas would diminish and the health and quality of trees would deteriorate. 6) Effects on Human Sudden climatic changes cause people to adapt to new weather continually and lead to more sicknesses. Moreover, air pollution makes people more likely to suffer from respiratory diseases with increasing incidence. Source: Hong Kong Observatory http://www.weather.gov.hk/wxinfo/climat/greenhs/e_grnhse.htm <The article is edited by Education Bureau, Curriculum Development Institute (Science Education Section)> 27