Ozone Depletion (Causes and Effects)

OZONE DEPLETION

describes two distinct, but related observations: a slow, steady decline of about 4% per decade in the total volume of ozone in Earth's stratosphere (ozone layer) since the late 1970s, and a much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions during the same period. The latter phenomenon is commonly referred to as the ozone hole. In addition to this well-known stratospheric ozone depletion, there are also tropospheric ozone depletion events, which occur near the surface in polar regions during spring.

The detailed mechanism by which the polar ozone holes form is different from that for the mid-latitude thinning, but the most important process in both trends is catalytic destruction of ozone by atomic chlorine and bromine.^[1] The main source of these halogen atoms in the stratosphere is photodissociation of chlorofluorocarbon (CFC) compounds, commonly called freons, and of bromofluorocarbon compounds known as halons. These compounds are transported into the stratosphere after being emitted at the surface.Both ozone depletion mechanisms strengthened as emissions of CFCs and halons increased

CAUSES OF OZONE DEPLETION.

Causes of Ozone Depletion

Earth's surface, ozone is constantly being produced and destroyed naturally. This ozone layer filters out UV rays from the Sun and protects life on Earth. Usually there is a fine balance between the build up and loss of ozone. However, in the 1970s it was discovered that man-made chemicals called CFCs were destroying the ozone in the ozone layer.

CFCs contain chlorine which reacts with ozone at the low temperatures high up in the atmosphere. Once the chlorine has broken up one ozone molecule, it is freed to repeat the process again and again, up to 100,000 times. Thankfully, we have banned the use of new CFCs since 1995. However, because CFCs remain High up in the atmosphere, in a region called the stratosphere between 19 and 30 km above the in the air for a long time, they will continue to affect the ozone layer well into the 21^st century.

EFFECTS OF OZONE DEPLETION

Even minor problems of ozone depletion can have major effects. Every time even a small amount of the ozone layer is lost, more ultraviolet light from the sun can reach the Earth.

Every time 1% of the ozone layer is depleted, 2% more UV-B is able to reach the surface of the planet. UV-B increase is one of the most harmful consequences of ozone depletion because it can cause skin cancer.

The increased cancer levels caused by exposure to this ultraviolet light could be enormous. The EPA estimates that 60 million Americans born by the year 2075 will get skin cancer because of ozone depletion. About one million of these people will die.

In addition to cancer, some research shows that a decreased ozone layer will increase rates of malaria and other infectious diseases. According to the EPA, 17 million more cases of cataracts can also be expected.

The environment will also be negatively affected by ozone depletion. The life cycles of plants will change, disrupting the food chain. Effects on animals will also be severe, and are very difficult to foresee.

Oceans will be hit hard as well. The most basic microscopic organisms such as plankton may not be able to survive. If that happened, it would mean that all of the other animals that are above plankton in the food chain would also die out. Other ecosystems such as forests and deserts will also be harmed.

The planet's climate could also be affected by depletion of the ozone layer. Wind patterns could change, resulting in climatic changes throughout the world.