Greenhouse Effect: Climate Control and Global Warming

 
Global warming has become a hot environmental issue, but what is the science of the greenhouse effect and is there evidence that we are causing climate change? We all know that air provides us with oxygen but until recently few of us knew that the atmosphere plays another vital role. Without our thin blanket of air, Earth’s average temperature would be minus 18 degrees Celsius – too cold for most forms of life. In fact the atmosphere gives us a much more comfortable average temperature of around 15 degrees Celsius.

 

The energy that sustains life comes from the Sun, mostly as visible light.

• Clouds reflect a small part back into space, but most is absorbed by the Earth’s surface.
• The warm surface radiates energy back into the air, but as infrared waves which have longer wavelength than visible light.
• Most of this infrared is absorbed by air particles and the net result is a warming effect on the atmosphere.
• So the atmosphere lets the light energy in but traps the heat energy radiated back from the earth’s surface.
• This is the greenhouse effect.