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