1. GLOBALWARMING

2. BY THE END OF THE LESSONWe will be able to1. Describe the trends in global temperature2. Describe the Greenhouse Effect3. Describe the causes of global warming4. Describe the consequences of globalwarming 3. Changes in Global Average Temperatures 4. GLOBAL TEMPERATURES Generally, annual global temperature haverisen over the years. Annual global temperature started to increasein the late 1930s. The rate of increase is fastest 1980 and 2000,increasing by about 0.4C in 2o years. 5. ATMOSPHERE Refers to the layer of gases that surrounds theEarth. Warms the Earths surface by trapping theheat from the Sun. Gases that traps the heat from the Sun areknow as greenhouse gases e.g. water vapour, carbon dioxide, methane,nitrous oxide, chlorofluorocarbons (CFCs) 6. GREENHOUSE EFFECT Refers to the warming process brought aboutby the the greenhouse gases in theatmosphere. Average Earths temperature: 15C Without greenhouse effect: -18C 7. GLOBALWARMING Amount of greenhouse gases in theatmosphere has doubled over the last 2centuries. More heat is trapped in the atmosphere,leading to enhanced greenhouse effect. The result is the increase in temperaturesaround the world, known as global warming. 8. CAUSES1. Increase in the amount of carbon dioxidereleased due to the burning of more fossil fuelsand forests.2. Increase in the amount of nitrous oxide releasedfrom emissions from more vehicles.3. Increase in the amount of methane released dueto increased cattle-rearing activities, producedwhen cows belch.4. Use of CFCs, released by the use of aerosolsprays, form packaging and solvents inindustries. 9. CONSEQUENCES1. Changes in weather condition2. Impact on plants3. Impact on animals4. Impact on people5. Rising sea levels 10. CONSEQUENCES1. Changes in weather condition Global warming may lead to fasterevaporation from water bodies, This will lead to dryer climates becoming drierresulting in prolonged droughts. On the other hand, the wetter climatesbecome wetter due to more water vapour inthe air, resulting in more flooding. 11. CONSEQUENCES2. Impact on plants As different types of vegetation requiredifferent climatic conditions, vegetationgrowth around the world will be affected whenthe climate changes. For example, countries such as Thailand andCambodia may find it difficult to grow rice,while countries such as Alaska may find that awarmer climate allow people to grow newcrops. 12. CONSEQUENCES3. Impact on animals As different animal are adapted to differentclimatic conditions, animals will be affectedwhen the climate changes. For example, animals who survives only in lowtemperatures such as the yaks and polar bears,may have to migrate to cooler areas whentemperatures rise or face extinction. 13. CONSEQUENCES4. Impact on people As temperature rises, mosquitoes wouldmultiply more rapidly as they thrive underhigh temperatures, leading to the spreaddisease such as dengue fever and malaria. In addition, the increase in the number of hotdays can also increase the chances ofdehydration and stroke. 14. CONSEQUENCES5. Rising sea levels The rise in the Earths temperature will causethe polar ice caps to melt, which contain morethan 70 percent of the worlds fresh water. This would lead to rising sea levels and putlow-lying cities such as Venice and Singaporeas risk. 15. OZONE DEPLETION 16. BY THE END OF THE LESSONWe will be able to1. Describe the ozone layer2. Describe the causes of ozone depletion3. Describe the consequences of globalwarming 17. OZONE LAYER AND DEPLETION Contains the ozone gas and lies 15 50kmabove the Earths surface. Acts as a shield against ultraviolet rays fromthe Sun. The gradual destruction of the ozone layer isknown as ozone depletion. 18. CAUSE Chlorine found in CFCs have the ability todestroy ozone molecules in the ozone layer. 19. CONSEQUENCES1. Impact on animals and plants Ultraviolet radiation can be damaging to planttissues and may destroy crops, leading todecline in food supply. Ultraviolet radiation also kills plankton, whichis food for many animals in the seas and affectthe food chain. 20. CONSEQUENCES2. Impact on people Increased amount of ultraviolet radiation cancause skin cancer which may lead to death. Exposure to ultraviolet radiation can alsocause cataract, which can lead to blindness. 21. MEASURES TO REDUCE IMPACT OF GLOBALWARMING AND OZONE DEPLETION1. International efforts Montreal Protocol Kyoto Protocol2. National efforts Using alternative sources of energy Enforcing laws and regulations Reducing use of CFCs3. Individual efforts 22. MEASURES TO REDUCE IMPACT OF GLOBALWARMING AND OZONE DEPLETION1. International efforts Montreal Protocol A treaty signed in 1987 in Montreal, Canada,that limit the production and use of CFCs. Most countries who signed the treaty agreedto stop using CFCs. Since the treaty, the rate of depletion of theozone layer has slowed down considerably. However, some developing countries arefacing difficulties in practicing the treaty dueto low levels of technology. 23. MEASURES TO REDUCE IMPACT OF GLOBALWARMING AND OZONE DEPLETION1. International efforts Kyoto Protocol A treaty signed in 1997 in Kyoto, Japan, thatrequires developed countries to reduce theirgreenhouse gases. By 2005, 141 countries that contribute 55% ofgreenhouse gases have acceded to the treaty. However, some developed countries did notaccede to the treaty as they were concernedthat the profits of their industries would beaffected. 24. MEASURES TO REDUCE IMPACT OF GLOBALWARMING AND OZONE DEPLETION2. National efforts Using alternative sources of energy Governments of countries can promote the usageof vehicles that run on alternative fuel, suchbatteries. Enforcing laws and regulations Governments can impose laws to reduce theemission of greenhouse gases. Governments can also encourage industries toimprove energy efficiency by finding ways to useless energy to do the same amount of work. 25. MEASURES TO REDUCE IMPACT OF GLOBALWARMING AND OZONE DEPLETION2. National efforts Reducing use of CFCs Governments can make it illegal to useproducts containing CFCs. Governments can also develop alternatives toreplace CFCs, such as the use of ozone-friendlychemicals to replace CFCs in air-conditioners. 26. MEASURES TO REDUCE IMPACT OF GLOBALWARMING AND OZONE DEPLETION3. Individual efforts Reduce emissions of greenhouse gases Take public transport Practice 3Rs Reduce ozone depletion Dont use products that contain CFCs Educate friends and family on consequencesof ozone layer depletion, Encourage friends and family not to use non-ozonefriendly products 27. END