1、Unit 4 Global warming,Group 1,2 What causes the global warming? Human activity or a random but natural phenomenon? Group 3,4 What is the terrible consequences of the global warming?,Think about:,Human beings - energy - greenhouse gases - greenhouse effect - global warming,When we talk about this pro

2、blem, we naturally link it to the use of energy and the environmental pollution.,But firstly and importantly, energy makes a great difference to our lives. What things do we use energy for?,Things that use energy around us or at any other places:,Where does all this energy come from?,Wind energy is

3、used as power to produce electricity .,Windmills,where electricity is produced by burning coals.,The coal power stations,in which oil is refined and made pure.,The Oil Refineries,a facility designed to convert nuclear energy into electricity.,A nuclear power plant,on the roof of a house on a bright

4、sunny day are used to collect solar energy, making your house warm or heating your water.,Solar panels,are used to keep back water and raise its level for irrigation or for producing electricity, etc.,The Hydro-electric dams,Guess it!,Uranium Ore (鈾礦石) The element uranium does not occur in pure form

5、 in nature but is found in minerals such as carnotite（釩鉀鈾礦）, pictured here.,What source of energy?,Geysers(間歇泉),Geothermal (地?zé)岬? Energy Plant,Those energy can renew themselves and never run out.,Non-renewable energy,One day they will run out.,Definition,Renewable or non-renewable?,Renewable or non-r

6、enewable?,Coal Oil Natural gas Uranium (鈾),Wind (wind power) Sun (solar energy) Water (hydro-electric power) Plant waste (biomass energy) Hot springs or geysers (geothermal energy) The sea (tidal energy),Fossil fuels,Non-renewable,Renewable,Fossil fuel(化石燃料): Ancient animal and plant material below

7、the surface of the earth with a high carbon content, such as coal, oil and natural gas, which can be burnt to produce energy; also known as non-renewable energy because once they are used they have gone forever; they cannot be renewed.,What are fossil fuels?,coal,oil,natural gas, ,Why?,Fossil Fuels,

8、greenhouse effect,A greenhouse,A greenhouse is made of _ and is used for growing _, especially during _ weather.,What is a greenhouse made of and used for?,glass,plants,cold,The air inside is warm because the glass traps the heat from the sun and keeps it from escaping. This makes the greenhouse hea

9、t up and so the plants can grow throughout the cold period.,How does a greenhouse work?,Greenhouse effect,The greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere (water vapor, carbon dioxide, nitrous oxide, and methane, for example) trap en

10、ergy from the sun. Without these gases, heat would escape back into space and Earths average temperature would be much colder. Because of how they warm our world, these gases are referred to as greenhouse gases.,The Greenhouse Effect,Without this greenhouse heating, the Earths average temperature wo

11、uld be only about -73C (-100F); even the oceans would be frozen under such conditions, such as the Moon and the Mars.,Mars,Moon,What Are Greenhouse Gases?,Some greenhouse gases occur naturally in the atmosphere, while others result from human activities. Naturally occurring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases.,Owing to the rise in atmospheric carbon dioxide caused by mode