Greenhouse effect

Sources, Causes & Impacts

Interpretation of global warming

Global warming is a long-term climate change which raises the temperature of the atmosphere

It is the result of intensification of the greenhouse effect.

Global warming is caused by a layer of greenhouse gases in the atmosphere.

The more the greenhouse gases emitted, the more the heat will be trapped.

Sources

Where come the GHGs?

Sources of greenhouse gases (GHGs)

Carbon dioxide (CO2) :

- combustion of fossil fuels

- deforestation

- incinerators

- industrial production

Sources of greenhouse gases (GHGs)

Methane (CH4) :

- cattle rearing

- rice growing

- landfill sites

- sewage disposal

Sources of greenhouse gases (GHGs)

Nitrous oxide (N2O) :

- biomass burning

- plants powered by fossil fuel

- industrial production

Sources of greenhouse gases (GHGs)

Chlorofluorocarbons (CFCs) :

- refrigerants

- aerosol sprays

- plastic foams

- solvents

Causes

Of the Intensified Greenhouse Effect

Causes of intensified greenhouse effect

Natural factors- variation in the Earth’s orbit

e.g. at the perihelion- variation in polar axis

e.g. warmer season with a larger angle and more tilted axis

- variation in Solar activity e.g. lower temperature when sunspots appear dark

- variation in aerosols e.g. their size and reflectivity may cool or warm the air

Causes of intensified greenhouse effect

Human activties

- burning of fossil fuels

e.g. coal & oil

- deforestation

e.g. burning of forests & shrinking of the carbon sink

- agricultural activity

e.g. cattle ranching & rice cultivation release methane

- landfill sites

e.g. decomposition releases methane

Impacts

Impacts of global warming

Physical environment - Climate change

- drier tropical areas

- decrease in freshwater storages

- more temperate conditions in high latitudes

- increased evaporation & changing rainfall pattern

- Increased energy level in the atmosphere, more extreme weather & climate conditions

Impacts of global warming

Physical environment – Rise in sea-level

- melting of ice caps and glaciers

- flooding of low-lying coastal areas

- expansion of sea water under high temperature

Impacts of global warming

Physical environment – Soil

- Increase in soil moisture deficit

- Lower water-holding capacity

- more soil erosion

- Lower productivity of the land

Impacts of global warming

Physical environment – Plants / Animals

- disturbance to the food chain

- coral bleaching in tropical seas & oceans

- Major threat to biodiversity

Impacts of global warming

Socio-economic – Agriculture

- longer growing season in high-latitude regions

- more pests to lower crop yield

- dry summers give low production of cereal crops

- salinization destroys coastal farmland

Impacts of global warming

Socio-economic – Forestry

- reduction of coniferous forests in high-latitudes

- longer growing season for lumbering

Impacts of global warming

Socio-economic – Transport

- navgation on high-latitudes year-round - extreme weather to hinder navigation

e.g. storm & coastal flooding

Impacts of global warming

Socio-economic – Recreation

- shortened winter hinders sports activities

- extended summer favours qauatic sports

Impacts of global warming

Socio-economic – Energy

- more demand in summers: air-conditioning*

- less demand in winters: less heating

Impacts of global warming

Socio-economic – Health risks

- more heat waves: more heart attacks, heat stroke

- less freshwater supply: lack of fresh & safe drinking water

Other impacts?

Besides the physical environment and the socio-economic concerns

Impacts of global warming

Political – international cooperation?

- Who gains?- Who loses?

Impacts of global warming

Impacts of global warming

Maldives cabinet held underwater meeting in 2009

Impacts of global warming