What Are Greenhouse Gases?                                                              

10308_20922_1.pngMany chemical compounds found in the Earth’s atmosphere act as “greenhouse gases.” These gases allow sunlight to enter the atmosphere freely. When sunlight strikes the Earth’s surface, some of it is re-radiated back towards space as infrared radiation (heat). Greenhouse gases absorb this infrared radiation and trap the heat in the atmosphere. Many gases exhibit these “greenhouse” properties. Some of them occur in nature (water vapor, carbon dioxide, methane, and nitrous oxide), while others are exclusively human made (certain industrial gases). Levels of several important greenhouse gases have increased by about 25 percent since large-scale industrialization began around 150 years ago. During the past 20 years, about three-quarters of human-caused emissions came from the burning of fossil fuels.

What Effect Do Greenhouse Gases Have On Climate Change?

In computer-based models, rising concentrations of greenhouse gases produce an increase in the average surface temperature of the Earth over time. Rising temperatures may, in turn, produce changes in precipitation patterns, storm severity, and sea level commonly referred to as “climate change.”

What Are the Sources of Greenhouse Gases?

In the Canada greenhouse gas emissions come primarily from the combustion of fossil fuels in energy use. Energy use is largely driven by10308_20746_0.jpg economic growth with short-term fluctuations in its growth rate created by weather patterns affecting heating and cooling needs, as well as changes in the fuel used in electricity generation. Energy-related carbon dioxide emissions, resulting from the combustion of petroleum, coal, and natural gas, represented most of the human-caused greenhouse gas emissions.

Today's atmosphere contains 32 per cent more carbon dioxide than it did at the start of the industrial era. Levels of methane and carbon dioxide are the highest they have been in nearly half a million years. The Kyoto Protocol covers six greenhouse gases - carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride. Of these six gases, three are of primary concern because they are closely associated to human activities.

Carbon dioxide is the main contributor to climate change, especially through the burning of fossil fuels.

Methane is produced naturally when vegetation is burned, digested or rotted without the presence of oxygen. Large amounts of methane are released by cattle farming, waste dumps, rice farming and the production of oil and gas.

Nitrous oxide, released by chemical fertilizers and burning fossil fuels, has a global warming potential 310 times that of carbon dioxide.



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