Ozone Depletion

What is the ozone layer and where is it found? The ozone layer is located in the stratosphere, the layer of the atmosphere at an altitude of 15-40 km

What is the function of the ozone layer? ozone absorbs ultraviolet solar radiation. What is Ozone? Ozone is a molecule made of three oxygen atoms

So…What’s the issue with the ozone layer? These satellite images below show the growth of the ozone hole (blue, then purple, then red) over the past two decades.

Chloroflouorocarbons (CFC’s) How is ozone depleted? Chloroflouorocarbons (CFC’s) Chlorofluorocarbons (CFCs) are hydrocarbons in which some or all of the hydrogen atoms are replaced by chlorine and fluorine. Uses: coolants for refrigerators, air conditioners, cleaning solvents, and as a propellant in spray cans of everyday products such as deodorants, hairspray, and paint.

The chemical reaction that destroys ozone.

Where is the ozone hole? CFCs migrate towards the South Pole during the S. Hemisphere winter due to global wind patterns Hole mostly over Antarctica, but shifts slightly with seasons- worst in Spring (Sept-Nov) 1980s- Increase in melanoma (skin cancer) in residents of New Zealand and Australia

“GOOD UP HIGH, BAD NEARBY” “Good Up High”- Protects all life on Earth from UV radiation in the stratosphere. We NEED this ozone for life to function on Earth “Bad Nearby”- Ozone is a secondary pollutant that can cause respiratory problems, creates smog and damages plants

Why is a hole in the ozone a problem? As ozone in the stratosphere decreases, more UV light is able to pass through the atmosphere and reach Earth’s surface. UV light is dangerous to life because it destroys DNA, the genetic material ALL CELLS need Exposure to UV light makes the body more vulnerable to skin cancer, and may cause other damaging effects to the human body.

What have we done to protect the ozone layer? Montreal 100+ nations made an agreement, called the Montreal Protocol, to sharply limit their production of CFCs. 1987 Copenhagen At a second conference in Copenhagen, Denmark in 1992, developed countries agreed to eliminate most CFCs use by 1995 1992

Updates on CFCs and Ozone Jan 1996- US and Europe ends CFC production 2000- Maximum CFC concentrations in stratosphere reached 2010- CFC production ends world-wide The future…. 2030- HCFC alternatives are phased out 2040- HCFC production ends globally 2050- Springtime Antarctic Hole disappears

Describe in 1 sentence what is happening in the diagram below. The hole in the ozone has grown significantly over the past two decades over the continent of Antarctica

What causes ozone depletion? A - Acid Rain B - Volatile Organic Compounds C - Chloroflourocarbons D - Thermal Inversion

What happens to chlorine after it breaks down one molecules of ozone? A – It move on to break down another molecule of ozone B – It creates acid rain C – It destroys aquatic ecosystems D – It disappears

What does “good up high – bad near by” mean? Ozone in the stratosphere is helpful because it protects us from harmful UV radiation Ozone on the ground level is toxic to humans and breaks down before reaching the stratosphere – so it can’t be used to replace the missing ozone

What are some effects on people from ozone depletion? UV rays can cause genetic damage that can lead to skin cancer or other health problems

What have we done about the hole in the ozone layer? A - We are moving ground level ozone into the stratosphere B - CFC’s were no longer produced and later banned from use C – We are cleaning up the CFC’s from the atmosphere over Antarctica D - Nothing