Global Warming
Q:What is global warming? A:Global warming means a progressive rise in
the mean annual temperature in the whole world.
Q:What causes global warming? A:It’s mainly due to the greenhouse effect.
Greenhouse effect
Natural greenhouse effect
Enhanced greenhouse effect
Types of greenhouse gases
carbon dioxide (CO2)methane (CH4)nitrous oxide (N2O)chlorofluorocarbons (CFCs) ozone (O3)water vapour (H2O)
Carbon dioxide
Methane
Nitrous Oxide
Chlorofluorocarbons
Chlorofluorocarbons
Greenhouse gas SourcesCarbon Dioxide (CO2) 1) Burning of fossil fuel
2) Land-use change (deforestation)Methane (CH4) 1) Biomass burning
2) sewage disposal, landfill sites3) Rice paddies
Nitrous Oxide (N2O) 1) Biomass burning2) Fossil-fuel combustion3) Fertilizers4) vehicle exhausts, power stations
Ozone (O3) Photochemical reactions involving O2Chlorofluorocarbons (CFCs) Industrial production, e.g.refrigerators,
aerosol sprays, solvents, foams
Consequences of greenhouse effectRise in sea levelDisease to human e.g. skin cancerDying forests Change in climate
Impact on human life
Economic Impact:impact on low-lying coastal areas and islands
Agricultural Impact:changing the soil moisture contents
Effects on Aquatic systems:reduce fish populations, and the abundance of freshwater species