Unit4_Global_warming课件58新人教版选修6）.ppt

First, lets see the defination of greehouse. A green house is made of _____ or ____ and is used for _____plants, especially during _____ weather. The air inside is _____ because __________________________________________, which makes the greenhouse _____ and so the plants can grow throughout the cold period. What are the greenhouse gases？ Where do they come from？ * * * * * * * * * * wind solar energy water creature energy energy nuclear petroleum Natural gas coal Are they renewable or non-renewable? On the one hand, modern people can’t bear the life without these energy, but on the other hand, the extensive use of energy makes the earth’s temperature increasing all the time.--- How? Because they release carbon dioxide. What is carbon dioxide? It is a kind of greenhouse gases. What are greenhouse gases? Is the global warming a random phenomenon? During the 20th century, the temperatureof the earth rose about one degree Fahranheit. Is it much to you? But it is a rapid increase when compared to other natural changes. But how has this come about? All the scientists subscribe to such a view that the increase in the tempertature is due to the burning of fossil fuels to produce energy. Refer to those fuels that are non-renewable such as coal, natural gas and oil and so on. This process produce some byproducts, which are called _____________________ greenhouse gases H2O（g） Freon O3 CO CH4 CO2 Greenhouse gases the most important Why? Why is carbon dioxide the most important in these gases? Because the level of carbon dioxide has increased greatly over the last 100-150 years. What is scientist Charles keelings accurate measurements? He found that between these years the carbon dioxide in the atmosphere went up from around 315 parts to around 370 parts per millon. The function of greenhouse gases Consideration: How is global warming occurring? The function of greenhouse gases But is it only fossil fuels that resulted in the global warming? ---NO