Ozone DepletionBy JM and Jake

The Ozone Cycle

A Hole in the Ozone Layer?

Not exactly… It is actually more of a depression in normal ozone levels.

1974- Molina and Rowland published a study that suggested the dangers of CFCs to the ozone in high frequencies of UV. This caused the US to ban CFCs in aerosols in 1978, but allowed CFCs to remain in refrigerants and coolants.

In 1984, British scientists measured ozone levels to be 35 percent lesser than the average in the 1960s.

What is the largest size (in square km) that the ozone hole has reached?

In September of 2006, the ozone hole was revealed to be 29.5 million square km in area. Larger than North America, it stretched as far as lower South America where its effects were felt in Chile and Argentina.

In comparison, the original recorded size was 1.09 million square km in area, in 1980 and North America is about 25 square kilometers in area, every year.

1980 2006

So what causes ozone depletion?

Primary cause is chlorine-containing gases.

Chilling arctic temperatures.

Sunlight in Spring. Eventually breaks up ozone

and closes.

What are the consequences of ozone depletion? (Class discussion.)

Increase in risk of skin cancer. Increases risk for other humane diseases.

The reduction in stratospheric ozone and clouds.

Increased troposphere ozone.

Decrease in production of crops.

How does ozone depletion relate to global warming?

A lack of ozone causes the stratosphere to absorb less solar radiation, and as a result cools the stratosphere while warming up the troposphere. The greenhouse effect and global warming are both connected to the prediction of a cooling stratosphere.

The same chemicals that cause ozone depletion also cause the greenhouse effect. Namely, CFCs.

Syllabus Statement

G.3.9Outline the effects of ultraviolet (UV) radiation on living tissues and biological productivity. UV radiation is likely to cause immune system suppresion.

It can also cause immense sunburn, on top of the previously listed increase in risk for skin cancer.

G.3.10Outline the effect of chlorofluorocarbons (CFCs) on the ozone layer. CFCs destroy the ozone in their century-long lifetime. The

gases dissociate, and catalyze ozone destruction.

G.3.11State that ozone in the stratosphere absorbs UV radiation.

Review!!!

Who were the first scientists to document the effect of CFCs on ozone levels?

What are the clouds that form during winter in the Antarctic ozone hole?

What is an effect from UV radiation on living tissue or biological productivity?

How do CFCs destroy the ozone layer?

How are ozone depletion and global warming connected?