THE OZONE LAYER

What is it?Where is it?

Why is it important to life on Earth?How are we as humans affecting it?

What is the ozone layer?What is the ozone layer?

The ozone layer is a The ozone layer is a layer of gas consisting layer of gas consisting of Oof O33 molecules, molecules,

called ozone, that called ozone, that forms when free forms when free Oxygen molecules Oxygen molecules bond to Obond to O22 molecules. molecules.

OzoneOzone

Ozone is a molecule Ozone is a molecule consisting of oxygen consisting of oxygen atoms.atoms.

Ozone gas can be Ozone gas can be created or destroyed created or destroyed by the sun’s by the sun’s UltraViolet rays as UltraViolet rays as shown in the picture shown in the picture to the right.to the right.

Where is the ozone layer?Where is the ozone layer?

The ozone layer is a The ozone layer is a protective layer of gas protective layer of gas molecules located molecules located within the stratosphere.within the stratosphere.

Ozone gas also exists Ozone gas also exists in the troposphere and in the troposphere and at ground level, but at ground level, but most is located within most is located within the stratospheric layer the stratospheric layer shown to the right.shown to the right.

Earth’s AtmosphereEarth’s Atmosphere

Why is it important to life on Why is it important to life on Earth?Earth?

On a daily basis, the sun radiates its energy toward On a daily basis, the sun radiates its energy toward Earth. One form of this energy is UltraViolet radiation, Earth. One form of this energy is UltraViolet radiation, also known as UV rays.also known as UV rays.

UV rays are relatively high energy waves that provide UV rays are relatively high energy waves that provide Earth with the warmth it needs to support life as we Earth with the warmth it needs to support life as we know it.know it.

Ultra-Violet RadiationUltra-Violet Radiation

UV rays penetrate UV rays penetrate the Earth’s the Earth’s atmosphere at 3 atmosphere at 3 slightly different slightly different wavelengths called wavelengths called UV-A, UV-B, and UV-A, UV-B, and UV-C rays.UV-C rays.

So, why is the ozone layer So, why is the ozone layer important to life on Earth?important to life on Earth?

The stratospheric ozone The stratospheric ozone layer completely stops layer completely stops the penetration of UV-C the penetration of UV-C rays and eliminates rays and eliminates most of the UV-B rays.most of the UV-B rays.

Therefore, the ozone Therefore, the ozone layer protects life on layer protects life on Earth from the harmful Earth from the harmful effects of solar radiation effects of solar radiation on a daily basis.on a daily basis.

So what might life be like without So what might life be like without the ozone layer?the ozone layer?

How are we as humans affecting How are we as humans affecting the ozone layer?the ozone layer?

Since 1928, Chlorofluorocarbons have been Since 1928, Chlorofluorocarbons have been produced, originally as nonflammable produced, originally as nonflammable refrigerants for use in refrigerators, and refrigerants for use in refrigerators, and eventually for use in fire extinguishers, dry eventually for use in fire extinguishers, dry cleaning agents, pesticides, degreasers, cleaning agents, pesticides, degreasers, adhesives, and as propellants for aerosol adhesives, and as propellants for aerosol products.products.

As these CFCs have been released into the As these CFCs have been released into the atmosphere, the level of ozone in the atmosphere, the level of ozone in the stratosphere has decreased.stratosphere has decreased.

CFCs have an estimated lifespan of more CFCs have an estimated lifespan of more than 100 years.than 100 years.

CFCs and OzoneCFCs and Ozone

And the effects of all those CFCs... And the effects of all those CFCs...

So what about the hole in the So what about the hole in the ozone layer?ozone layer?

October 1979 October 2007

The Ozone HoleThe Ozone Hole

Since the 1970’s the ozone hole has Since the 1970’s the ozone hole has been increasing in size over the been increasing in size over the Antarctic.Antarctic.

For the first time, in September of 2000, For the first time, in September of 2000, the ozone hole became so large it the ozone hole became so large it actually left populated areas of southern actually left populated areas of southern Chile fully exposed to the effects of the Chile fully exposed to the effects of the Sun’s UV rays.Sun’s UV rays.

Chile’s Ozone HoleChile’s Ozone Hole

How does ozone depletion affect How does ozone depletion affect global warming and ultimately global warming and ultimately

climate change?climate change? As ozone levels in the stratosphere are As ozone levels in the stratosphere are

depleted, more solar radiation penetrates the depleted, more solar radiation penetrates the Earth’s atmosphere.Earth’s atmosphere.

This affect results in an increase in solar This affect results in an increase in solar radiation reaching the Earth’s surface adding radiation reaching the Earth’s surface adding to an increase in surface temperature.to an increase in surface temperature.

In turn, global warming actually results in a In turn, global warming actually results in a warming of the troposphere, but a cooling of warming of the troposphere, but a cooling of the stratosphere, hindering the ozone layer’s the stratosphere, hindering the ozone layer’s natural chemistry for repairs.natural chemistry for repairs.

So what are we doing about it?So what are we doing about it? After the discovery of ozone depletion in the late 1970’s, many After the discovery of ozone depletion in the late 1970’s, many

countries agreed that something must be done worldwide to countries agreed that something must be done worldwide to stop the production of man-made, ozone harmful products.stop the production of man-made, ozone harmful products.

The international community adopted the Vienna Convention in The international community adopted the Vienna Convention in 1985 followed by the Montreal Protocol in 1987. 1985 followed by the Montreal Protocol in 1987.

The latest reports confirm that it has led to the phasing out of The latest reports confirm that it has led to the phasing out of about 95% of the consumption of ozone-depleting substances about 95% of the consumption of ozone-depleting substances (ODS) listed in the agreement. In turn, this has led to the (ODS) listed in the agreement. In turn, this has led to the prospect of the ozone layer recovering by 2050 to 2075.prospect of the ozone layer recovering by 2050 to 2075.

Furthermore, the phasing out of ozone-depleting substances Furthermore, the phasing out of ozone-depleting substances has helped to fight climate change since many of these has helped to fight climate change since many of these chemicals are also powerful greenhouse gases. According to a chemicals are also powerful greenhouse gases. According to a recent study, the phasing out of substances under the Protocol recent study, the phasing out of substances under the Protocol led to more reductions in greenhouse gases than what is led to more reductions in greenhouse gases than what is foreseen under the Kyoto Protocol. foreseen under the Kyoto Protocol.

What can we do, as concerned What can we do, as concerned citizens, to ensure that our citizens, to ensure that our

children have a viable planet to children have a viable planet to inhabit?inhabit?