GREENHOUSE GASES

Greenhouse gases trap heat. If too many accumulate in our atmosphere, we're in big trouble.

Total national greenhouse gases emissions in Canada in 2005: 279,842,143 tonnes CO2 equivalent (total all gases).¹

It's important to get the gist of GHGs: some of them are released into the atmosphere through natural processes. For thousands of years they occurred naturally, the cycles were all working fine, and the earth was a lovely, hospitable place. But other greenhouse gases are created and emitted solely through human activities, like industry and transportation. Those are the ones that are causing the problems. Some greenhouse gases, like carbon dioxide, fall into both categories. The ones that contribute to global warming, the really important ones, are as follows:

• Carbon Dioxide(CO₂): Carbon dioxide enters the atmosphere through the burning of fossil fuels (oil, natural gas, and coal), solid waste, trees and wood products, and also as a result of other chemical/industrial processes (manufacturing cement). Carbon dioxide can be removed from the atmosphere (or “sequestered”) when it is absorbed by plants as part of the biological carbon cycle.

• Methane (CH₄): Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from livestock and other agricultural practices and by the decay of organic waste in municipal solid waste landfills. Methane is also stored in buried organic deposits. Vast amounts of methane are stored under the permafrost in the northern hemisphere.

• Nitrous Oxide (N₂O): Nitrous oxide is emitted during agricultural and industrial activities, as well as during combustion of fossil fuels and solid waste. 

• Fluorinated Gases: Hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride are synthetic, powerful greenhouse gases that are emitted from a variety of industrial processes. Fluorinated gases are sometimes used as substitutes for ozone-depleting substances (i.e., CFCs, HCFCs, and halons). These gases are typically emitted in smaller quantities, but because they are potent greenhouse gases, they are sometimes referred to as High Global Warming Potential gases (“High GWP gases”). 

^{1 Source: www.PollutionWatch.org}