全球变暖 (英文).ppt

What is Global Warming?Global warming is the observed century-scale rise in the average temperature of Earths climate system.全球变暖是指全球气温在近一百年来不断上升，呈现变暖的趋势，这样一种气候变化特征。The cause of global warming1.Natural cause:The green house effect2.Human reasons:Human activitiesThe green house effectThe greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases,and is re-radiated in all directions.Since part of this re-radiation is back towards the surface and the lower atmosphere,it results in an elevation of the average surface temperature above what it would be in the absence of the gases.温室效应是一个过程,从行星表面热辐射被大气吸收温室气体,并再次辐射向四面八方。因为这部分再辐射回到地表和低层大气,它导致海拔平均表面温度高于没有这部分气体。Human activities1.Industrial waste gases2.Deforestation3.Traffic jamIndustrial waste gasesDeforestitionTraffic jamWhatre the effects of global warmingNegative effects1.Cause the sea level to rise2.Melting glaciers3.Droughts4.Disappearance of species Positive effects1.make plants grow faster2.crops will produce moreDroughtsIf the earths average temperature 4 degrees Celsius,the world will have more than 30 million people water shortages.如果地球平均气温上升如果地球平均气温上升4摄氏度，全摄氏度，全球就会有球就会有30多亿人面临缺水问题。多亿人面临缺水问题。Melting glaciersthe earths poles island fate snow melt can lead to rising sea levels,many islands will be drowned,some island may not exist.地球两极冰雪融化会导致海平面上升，众多地球两极冰雪融化会导致海平面上升，众多岛屿将被淹没，一些岛国可能不复存在。岛屿将被淹没，一些岛国可能不复存在。So,let us do our best to solve this problem,or we will bear this problem in the future