Definition of Green House Gas

Greenhouse gases are a naturally occurring feature of the atmosphere. Without greenhouse gases, life as we know it on Earth would be impossible. However, there is increasing evidence that human intervention has had a definite and adverse effect on the level of greenhouse gases in the atmosphere, and has contributed to the phenomenon known as global warming, or climate change.

What are Greenhouse Gases?

• Greenhouse gases naturally surround the Earth and keep the planet warmer than it would be without them. Greenhouse gases allow sunlight to reach the earth, which heats the atmosphere and the surface. However, the greenhouse gases allow only part of the resulting heat to escape through the atmosphere back into space, trapping the rest, which results in warming. Without greenhouse gases, the Earth would be uninhabitable by humans and most life forms. Greenhouse gases include carbon dioxide, methane and nitrous oxide.

Carbon Dioxide

• Carbon dioxide, a colorless, odorless gas, is the most commonly known greenhouse gas. It is produced by burning carbon-based energy sources, such as coal and oil, and also biomass, or organic substances. It is also produced by land use change, as forests (trees and vegetation are an important point of storage for carbon dioxide because they use carbon dioxide for photosynthesis) are cleared for agricultural use. Slash-and-burn agriculture, where vegetation is burned and the soil allowed to absorb the burned vegetation as nutrients, also produces carbon dioxide.

Methane

• Methane is a colorless, odorless and highly flammable gas. Wetland drainage has a major detrimental effect on the natural methane production cycle of wetland regions. Microorganisms called Archaea live in the waterlogged soil, and mineralize organic carbon anaerobically. With reduced water tables, this process is interrupted. On the other hand, termites release an estimated 20 tons of methane into the atmosphere each year. Methane emissions from landfills have been estimated to be between 30 and 70 million tons annually.

Nitrous Oxide and Other Greenhouse Gases

• Nitrous oxide is also a colorless gas, but has a sweet odor. A major source of nitrous oxide release into the atmosphere is livestock and feed, which is estimated to be responsible for 1 to 2 million tons of nitrous oxide annually. The major source of nitrous oxide emissions is from the production of livestock feed, which involves large amounts of nitrogen based fertilizer. The management of livestock waste is another major source of nitrous oxide emissions.

  Chlorofluorocarbons (CFCs) were formerly used in aerosol sprays, refrigerators and air conditioners. However, their detrimental effect to the ozone layer led to their production being banned in the 1970s. The replacement for CFCs, known as hydrofluorocarbons (HFCs), are used in air conditioners and radiators. HFCs do not adversely affect the ozone layer, but they are a form of greenhouse gas.

Greenhouse Gases and Climate Change

• Human intervention is generally recognized in the scientific community as having had an impact on climate change. The human impact on climate change has been manifested through the increased production of greenhouse gases, primarily carbon dioxide, which has occurred since the beginning of the Industrial Revolution. The overall level of greenhouse gases is believed to have increased by about 25 percent in the last 150 years. The effects of climate change are said to have been responsible for such phenomena as rising sea levels, increased drought conditions and the melting of glaciers, including the polar ice caps.