Clean Tech 101

What are Greenhouse Gases and the Relationship between Greenhouse Gases and Climate Change

Gases Exhibitinh Greenhouse Gas Properties
What are the Sources of Greenhouse Gases
Carbon Dioxide Concentrations in the Earth's Atmosphere
The Effect of Greenhouse Gases on Climate Change


The Earth’s atmosphere possesses many chemical compounds that act as greenhouse gases. Greenhouse gases permits sunlight to penetrate the Earth’s atmosphere freely. The Earth’s surface reflects some of the sunlight as infrared radiation or heat back towards space.

However, the reflected infrared radiation gets absorbed by the greenhouse gases and  trapped in the Earth’s atmosphere. Over time, the amount of energy sent from the sun to the Earth’s surface is roughly equal to the amount of energy radiated back into space. This leaves the surface temperature of Earth roughly constant.

Gases Exhibiting Greenhouse Gas Properties

A number of gases exhibit greenhouse properties. Some gases such as water vapor, carbon dioxide, methane, and nitrous oxide occur in nature, while others such as aerosols are man-made.

The levels of a number of important greenhouse gases have increased since large-scale industrialization began around 150 years ago to about 25 percent. Around 75 percent of man-made carbon dioxide emissions during the past 20 years were from the burning of fossil fuels.

What are the Sources of Greenhouse Gases

Greenhouse gas emission mostly comes from the use of energy, which are driven largely by economic growth and the fuel used for the generation of electricity. In the U.S., greenhouse gas emissions from energy related applications such as the burning of petroleum or natural gas, represents about 82 percent of the total man-made emission.

Carbon Dioxide Concentrations in the Earth's Atmosphere

Carbon dioxide concentration in the atmosphere is regulated naturally by a number of processes commonly referred to as the carbon cycle. The carbon movement between the land and ocean and the atmosphere is dominated by natural processes such as photosynthesis of plants.

Although some of the man-made carbon dioxide emissions can be absorbed by these natural processes, it is estimated that about half is added to the atmosphere annually. The Earth’s positive imbalance between absorption and emission results in the continual growth in greenhouse gases in the atmosphere.

The Effect of Greenhouse Gases on Climate Change

In computer-based simulations, the rising concentrations in greenhouse gases overall causes an increase in the Earth’s average temperature. This in turn may cause changes in sea level, land use and weather. This phenomenon is commonly referred to as climate change.

Nevertheless, there is unpredictability in how the climate system differs naturally and reacts to the emission of greenhouse gases. Making progress in reducing uncertainties in projections of future climate will require better awareness and understanding of the buildup of greenhouse gases in the atmosphere and the behavior of the climate system.

Source: AZoCleantech
Last Update: 9th December 2007

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