What is Global Warming?

Essentially, global warming refers to the increase in global atmospheric temperatures as a result of increasing concentrations of greenhouse gases in the air around us. The atmosphere contains a whole host of greenhouse gases with the main culprits for temperature increase being carbon dioxide, methane, and water vapour (although nitrous oxide and a series of gases containing chlorine also contribute to global warming with the latter also having a characteristic to destroy the ozone layer)..

That greenhouse gases have a warming effect is indisputable and has been established in science for over a hundred years when Joseph Fourier and John Tyndale collectively discovered what we now know as the greenhouse effect. It was found that the naturally occurring greenhouse gases in our atmosphere prevent Earth from being completely frozen and lifeless. Without this layer of carbon dioxide, methane and water vapour in our atmosphere the global average temperature would be minus 18oC.

All greenhouse gases share a special characteristic that the more abundant gases in our atmosphere (oxygen and nitrogen) do not possess.  In scientific terms; greenhouse gases are opaque to long-wave infrared radiation. Heat coming in from the Sun is short-wave, and so passes straight through the atmosphere, but when this heat is re-radiated by the Earth, its wavelength becomes longer and some of the heat becomes trapped by the greenhouse gases in the atmosphere, which would otherwise have been sent back into space.

In laymans terms; greenhouse gases act just like the glass panels in a greenhouse, which allow sunlight through to warm the air inside, but then prevent the hot air from escaping.