What cause damage to the ozone layer?

Answer 1

Ozone depletion is the process where ozone holes are created in the ozone layer. It is caused due to the action of chloro-floro-carbons on the ozone molecule to break it down to oxygen.The substances that are causing ozone layer depletion are freons, CFC's etc..

These are called as ozone-depleting substances (ODS).

Answer 2

Briefly:

CFCs and similar man-made gases break down the ozone in the stratosphere allowing in harmful ultraviolet radiation. The ozone hole happens mostly in Antarctica where four months of winter darkness create ideal conditions for the destruction.

Ozone is a protective layer in the upper atmosphere. It is formed, when oxygen molecules absorb short wavelength ultra violet radiations from the sun. Ozone is mostly destroyed by the free radicals in the atmosphere. When compounds like CFCs (chlorofluorocarbons) are released, they are dissociated by sunlight into chloride radicals. These radicals attack ozone, thereby decreasing its concentration. This results in hole in the ozone layer.

The hole in the ozone layer happens because the ozone in the stratosphere is destroyed by chlorine and bromine from halogen atoms. These atoms come from man-made halocarbon refrigerator gases (chlorofluorocarbons [CFCs], freons and halons) which are emitted at ground level but move up into the ozone layer. These gases all contain chlorine and bromine.

Ozone (O3) is formed when ultraviolet (UV) light strikes an oxygen molecule (O2), converting it into two oxygen ions (O). These oxygen ions (O) combine with other oxygen molecules (O2) to form ozone (O3). Later, another oxygen ion (O) will combine with the ozone molecule (O3) to form two oxygen molecules (O2). This is the natural ozone-oxygen cycle of the earth.

The ozone layer prevents the harmful ultraviolet B-waves (UV-B) from reaching the earth. Increased exposure to UV-B is thought to be responsible for increases in skin cancer, eye cataracts and damage to plants and plankton. Because of this the nations of the world in 1989 adopted the Montreal Protocol which bans production of CFCs, halons and other ozone-depleting chemicals.

The ozone hole happens during the spring in Antarctica (Sept to Dec). Polar Stratospheric Clouds (PSCs) form during the all-dark winter. When spring arrives and UV light appears again, crystals of ice and nitric acid in these clouds help to release the chlorine and bromine atoms from the halocarbon gases. These destroy the ozone. (A single chlorine atom can continue destroying ozone for up to two years, reacting with up to 100,000 ozone molecules.)

Another view:Natural issues:

Because the concept of man made pollution doesn't cover all of what we see, another look at the issue is demanded. In the man induced theory, the depletion of ozone is due to release of man-made chemicals such as chlorofluorocarbon (CFC) compounds.

Over time these heavier then air chemicals work their way up into the upper stratosphere. CFC's break apart under UV radiation releasing chlorine atoms that would destroy ozone.

Assuming this man induced theory on the origin of the ozone hole is correct, the area most affected would be the mid-Latitude Northern Hemisphere where the industry and population centers in the U.S., Canada, Europe, India, Asia, Russia, China and Japan exist. This is precisely what is not happening! This area is where the least action occurs.

Instead, we are observing a substantial annual ozone hole in one area only, the Antarctic and then only during times of no sunlight (the polar winter). Once the sun returns, the hole disappears quickly. A substantially smaller hole (NASA calls this the dimple because it is so small) is also known to occur over the world's second cleanest area, the Arctic.

A second issue exists. The sun often generates explosions that produce bursts of high-energy protons. These are called Solar Proton Events. Ozone layer density on Earth can be dramatically affected by SPE's, which can locally decrease ozone content in the stratosphere up to 5%.

Some events that have caused serious dents in our levels of ozone levels can be measured using Nitrate Spike Signatures.

They show us large thinning of our ozone layer occurred prior to the creation of CFC's in September of 1859 and in July 1892.

Thirdly, There is growing evidence that ozone levels at the poles is directly connected to the strength of our magnetic fields. The ever weakening fields are believed to be assisting with the size and strength of the ozone hole. Projections for the hole, if tied to magnetic levels of the planet, are for an increasing hole, despite the banning of CFC's.

It is unfortunate that many confuse ozone depletion (which could be a man induced issue) with this natural event. Please see the related link below for a peer reviewed explanation of the natural event we refer to as the hole in the ozone layer;

Bad gases such as Carbon Dioxide and other fumes harm the Ozone layer. CFC (A fluorocarbon with chlorine; formerly used as a refrigerant and as a propellant in aerosol cans) is also the main problem in which the ozone has become thinner. It has been banned in 1966, but the effects are still slow.

The ozone hole is a natural event that occurs when it is winter at a pole. UV-C is required to replace ozone that is decayed (naturally or otherwise), and in winter at a pole, it gets no UV-C, so the ozone decays to very low levels. It also heals up towards spring, such that there is no ozone hole once UV-C from the Sun arrives.

See "How did the ozone hole occur?"

More information:

The "hole" in the ozone layer is not a hole in any real sense of the word, but a thinning of the amount of ozone in the atmosphere over the Antarctic during the end of the winter. This hole has been naturally occurring for centuries and is due, almost exclusively, to the lack of sunlight over this area during the long winter. A smaller, but similar situation occurs over the Arctic during the end of it's winter months. NASA refers to this thinning area as the dimple due to the small size when compared to the Antarctic's situation. Solar activity is also a known issue for the amount of ozone in our atmosphere. The largest known thinning of that we know of actually occurred in 1859 and is believed to have been caused by solar activity. CFC's are also having some contributory affect on the amount of thinning of the ozone.

Ozone depletion was observed to increase as emissions of halo-carbons increased.

Ozone is a protective layer in the upper atmosphere. It is formed when oxygen molecules absorb short wavelength ultra violet radiations from the sun. Ozone is mostly destroyed by free radicals in the atmosphere.

When compounds like CFCs (chlorofluorocarbons) and other halocarbons are released, they are dissociated by sunlight into chloride radicals. These radicals attack ozone, thereby decreasing its concentration. This results in a thinning of the ozone layer, and in polar regions, a hole.

The holes occur at the poles, and usually in Antarctica because of the extreme cold. During the winter polar stratospheric clouds form which are able to convert gases in the atmosphere into Cl (chlorine) and ClO (chlorine monoxide). When the sun arrives at the end of winter, that is the trigger to begin. This is why the hole is largest in spring.

The ozone hole occurs once a year at each pole. The southern polar hole is larger than the northern polar hole due the fact that the southern pole is much colder than the northern pole. The size of the hole is what is of concern and is caused by chlorofluorocarbons (CFCs) and halogens from human industry.

Ozone decays naturally with time. With the axial tilt that Earth has, once each year (local winter) each pole stops receiving the UV-C that turns some oxygen into ozone. So the ozone starts decaying, and a hole forms. The only ozone the pole gets at this time, diffuses in from areas that are still receiving UV-C. So the ozone would be exceedingly thin at this time. The presence of the polar jet stream prevents the ozone at the poles (during local winter) from being replenished as it is throughout the year otherwise.

Add contaminants to the mix, and the amount of ozone drastically decreases. Water vapor (natural and Man-sourced), chlorine (most commonly Man-sourced, carried by CFCs), and bromine (most commonly natural, but likely some Man-sourced, carried for example in halon) all have shown abilities in depleting ozone.

The concentration of ozone at any point is a balance of incident UV-C from the Sun (both making and destroying ozone), UV-B from the Sun (destroys ozone when absorbed), time, and compounds that can accelerate the decay of ozone.

The southern hole is larger because it is so much colder. It is cold enough to form something known as Polar Stratospheric Clouds (PSCs). These form a deposition site for the radicals in the atmosphere that are responsible for ozone depletion. These radicals can be recycled after use so that one molecule of contaminant (chlorine) is responsible for the destruction of several thousand molecules of ozone.

Answer 3

Erosion in the ozone layer is caused by a mixture of different things. Much of it however is caused by us, chlorine released from freons and halons that came from refrigerators, air conditions, fire extinguishers, etc. decomposes ozone back to ordinary oxygen.

Scientists have discovered a massive acceleration in the breakdown of the ozone above the Arctic, with a 30% reduction over the winter. 50% of the ozone has been wiped out by a combination of a build-up of clouds and, particularly, cold weather, which has created perilous conditions for the earth's protective layer of gases. Consistently low temperatures between November and February have combined disastrously with a build-up of clouds, some caused by emissions, between 14 km and 26 km above sea level. There were more clouds this year than had been measured in the last 20.

The build-up of clouds makes it harder for the atmosphere to break down chlorofluorocarbons (CFCs), the gas found in refrigerator and aerosol systems, which causes the ozone to deplete. Despite the fact that there has been a large-scale crackdown on the use of CFCs, there is still a build-up in the atmosphere, which was made more harmful by this winter's conditions.

The cooling of the atmosphere is understood to be a result of the presence of greenhouse gases in the atmosphere, but the relationship between the two is not understood well enough for scientists to make proper predictions on the rate of future depletion. Colder temperatures impact on the distribution of nitrogen oxides in the atmosphere, allowing ozone loss to continue for longer than usual.

"Overall, about 30% of the ozone layer was destroyed," said Markus Rex, from the Alfred Wegener Institute in Potsdam, Germany, part of the Cambridge-led consortium working on the project.

"This largely prevented the normal seasonal increase of the thickness of the ozone layer during winter and led to a thinner ozone layer in Arctic spring compared to warmer years."

The result, during late March of 2000 there was a significant increase in UV-B radiation and risks of sunburn in parts of Europe. The affected region reached as far south as northern Italy.

John Pyle, from Cambridge University, said: "If we had these levels of depletion over middle latitudes, it would be terrible for human health and the biosphere.

"Based on this, we wouldn't tell people to change behaviour - people still need to be careful of the sun. But it demonstrates that this problem hasn't gone away yet."

The Arctic ozone is normally considered more resilient than that over Antarctica, where complete ozone loss between 15 km and 20 km altitudes has been recorded regularly since the early 1980s. In comparison, this year's depletion in the Arctic is one of the worst recorded. However, since the early 1990s depletion has been recorded every year at levels of between 5% and 30%. In 1999/2000 the situation was slightly worse than this year, with around 65% depletion at 18 km above sea level.

Wildlife campaigners today led calls for the next government to prioritise cutbacks in carbon dioxide emissions.

The WWF conservation group, formerly known as the World Wildlife Fund, wants the next government to commit to year-on-year reductions in greenhouse gases to achieve its target of a 20% reduction by 2010.

Answer 4

CFC's cause damage to ozone layer. They react with ozone to deplete it.

Answer 5

CFC's cause damage to ozone. They react with ozone to deplete it.

Answer 6

The destruction of ozone layer is happening in both hemispheres. It is due to reckless use of CFC's.