Global Warming• The Sun rays are reflected from earth’s

surface as an Infrared radiation back into the atmosphere.

• Some of these Infrared radiations are absorbed by gases (such as CO2, methane, nitrous oxide, sulfur hexafluride, HFCs and PFCs) and re-radiated as heat, back to earth.

• This is green house effect.

Global Warming

Earth

Sun

Global Warming

• The chemical composition of the atmosphere is nitrogen (78%); about 21% is oxygen, which all animals need to survive;

and only a small percentage (0.036%) is made up of carbon dioxide which plants require for photosynthesis. .

Earth

Sun

Global Warming

Sun Rays

Earth

Sun

Global Warming

Sun

Earth

Infrared Rays (IR)

Infrared Rays (IR)

Global Warming

Sun

EarthGases

Global Warming

• Greenhouse gases re-emit some of this heat to the earth's surface. If they did not perform this useful function, most of the heat energy would escape, leaving the earth cold (about -18 ºC) and unfit to support life.

Sun

Earth

Heat

Global Warming

The atmospheric concentrations of carbon

dioxide, methane, and nitrous oxide have grown

by about 31%, 151% and 17%, respectively, between 1750 and

2000

Sun

Earth

However, ever since the Industrial Revolution began about 150 years

ago, man-made activities have added

significant quantities of GHGs to the atmosphere.

Global Warming• The three greenhouse gases most frequently found in nature

are:

• Carbon dioxide (CO2) – a naturally occurring gas released as a by-product of fossil fuel combustion, selected industrial processes and changes in the patterns of land-use, particularly deforestation. In terms of gross volume of emissions, it is by far the most important greenhouse gas. Carbon dioxide is given the base global warming potential value, 1.

Global Warming

• Methane (CH4) – a gas released in coal mining, landfill operations, livestock raising and natural gas/oil drilling (among other processes). Methane has a global warming potential of 21 (in other words, it is 21 times more potent in terms of global warming effect than carbon dioxide).

Global Warming• Nitrous oxide (N2O) – a gas emitted during

fertilizer manufacturing and fossil fuel combustion. The transportation sector is usually a significant contributor to N2O emissions. N2O has a global warming potential of 310. Human activity clearly contributes to the increased concentrations of CO2, CH4 and N2O in the atmosphere, but they can also be released through natural processes. It is expected that the vast majority of CDM projects will involved these gases.

Global Warming• In addition to these three greenhouse gases,

there are three additional classes of engineered gases, which occur on a very limited basis in nature.

• Hydrofluorocarbons (HFCs) – a group of gasses emitted in selected manufacturing processes and frequently used in refrigeration and air conditioning equipment. HFC-23, HFC-12, HFC-134a and HFC 152a have global warming potentials of 11,700, 2800, 1300 and 140 respectively.

Global Warming

• Perfluorocarbons (PFCs) – similar to HFCs, PFCs were developed and introduced as an alternative to ozone depleting CFCs and HCFCs. They are emitted in a variety of manufacturing processes. Their global warming potential ranges from 6.500 for CF4 to 9,200 for C2F6.

Global Warming

• Sulphur hexofluoride (SF) – the most potent greenhouse gas, released in a very limited number of manufacturing processes where it is used as a dielectric fluid. The global warming potential of SF6 is equal to 23,900, and one molecule of SF6 has the atmospheric lifetime of 3,200 years. Hence, SF6 represent the most dangerous group of anthropogenic-induced greenhouse gas emissions.

Global Warming• Each year about 27 billion tonnes of

carbon dioxide are belched out into the atmosphereOf our annual 27 billion tonnes carbon dioxide output;- 7 billion tonnes are absorbed by oceans; - 7 billion tonnes are taken up by forests,and; - 13 billion tonnes accumulate in the atmosphere each year. the atmosphere has risen much faster than expected, from an average of 13 to 18 billion tonnes.

Global Warming

• Developed countries produce Green House Gases - gases generated from human activities including industrial processes, fossil fuel combustion, changes in land use, such as deforestation

• Contributing to Green House Effect

Global Warming

• This creates global warming process that is threatening our current environment

• It melts polar ice caps

Global Warming

• Raises the sea level around the globe• To protect ourselves, the economy,

and our land from the adverse effects of climate change, we must reduce emissions of carbon dioxide and other greenhouse gases.