Greenhouse and Ozone Layer, Do You Know the Difference?

Working as an Environment Manager for large coal fired power station, I often get into the debate about the Green house effect or “Global Warming”. Quite often in my debates I often here the other person claim

“The Green house effect is all a big lie, it was only the other week I heard on the news that the hole in the ozone layer is getting smaller” or “didn’t we change the gas in our refrigerators years ago to stop global warming?”

The difference between the Greenhouse effect and the hole in the Ozone Layer has been a point of confusion for many people. So do you know the difference?

The Greenhouse Effect

The Greenhouse effect was proposed by Joseph Fourier in 1824 and first investigated quantitatively by Swedish scientist Svante Arrhenius in 1896.

The Earth receives energy from the sun in the form of visible and invisible radiation, including light. The earth absorbs around 70% of this radiation and reflects the remaining 30% back out into outer space. The greenhouse effect is the process of increasing the amount of radiation being absorbed by the earth, while decreasing the amount that is reflected.

So how are we absorbing more radiation? Most of the visible radiation is absorbed, or reflected by the earth it self. Ever been to the beach or snow on a really sunny day? That glare in your eyes is the sun’s light being reflecting back into outer space. The invisible radiation or “infrared waves”, however, are reflected by the atmosphere, not by the ground. The amount of reflection depends on the concentration of gases such as water vapour, carbon dioxide and methane in the atmosphere.

Increasing the concentrations of these components, increases the amount of invisible radiation the earth is absorbing. So how bad is it? With simple laboratory tests, Arrhenius, predicted that a doubling the carbon dioxide concentration in the atmosphere, the temperature will rise by about 5oC. This a large enough rise to cause serious havoc with the worlds environments, such as melt glaciers, cause an increase in storm severity and prolong droughts.

The Hole in the Ozone Layer

While global action to reduce carbon dioxide emissions is still only in the infant stages, the story about the hole in the ozone layer is becoming better every day. That’s because the hole is shrinking.

The atmosphere above the earth is made up of many layers. The lowest layer, reaching between 11 to 20km above the earths surface is the troposphere. This is the region where the green house gases are being trapped. Higher up above. Above this region is the stratosphere, ranging from 11km to 50km above the earths surface. In this region the ozone layer can be found.