Global warming refers to an average increase in the Earth's temperature, which in turn causes changes in climate - changes that can have devastating effects on our environment and our everyday lives. But how and why does this happen?

The earth and sun are in a constant relationship of heat exchange; the sun radiates heat toward the earth, which absorbs what it needs, and then releases the remaining heat back into the atmosphere. Both the sun and the earth depend upon the atmosphere to maintain a stable temperature suitable for us to live.

The atmosphere is comprised of an array of different naturally occurring gases. Of all of them, four are the major contributors to global warming -- carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and ozone (O3). Collectively, these gases are known as greenhouse gases and they play a primary role in regulating the temperature of our planet. While these gases are essential for life on Earth because they let the sun's heat reach the Earth and allow plants to use solar energy for photosynthesis, in excess they have devastating consequences.

Unfortunately, excessive greenhouse gases in the atmosphere can trap too much heat, effectively cooking the planet and causing major environmental havoc. Human activities are largely responsible for upsetting the natural balance of heat and gases in the environment.

Greenhouse gases are emitted from a variety of sources including major emitters like the electric power industry, transportation, industrial manufacturing, agriculture and commercial and residential sources.

Scientists estimate that we need to significantly reduce our greenhouse gas emissions to avoid irreversible damage to our planet. Left unchecked, climate change will lead to devastating environmental impacts including flooding and drought, wildfires, ocean acidification and increased species extinction.

If you would like to learn more about global warming just click on the following links: