Ozone Layer
The ozone layer is a thin part of the Earth’s atmosphere that absorbs almost all of the sun’s harmful ultraviolet light. “Ozone holes” are popular names for areas of damage to the ozone layer. This is inaccurate. Ozone layer damage is more like a really thin patch than a hole.
The ozone layer is one layer of the stratosphere, the second layer of the Earth’s atmosphere. The stratosphere is the mass of protective gases clinging to our planet.
The stratosphere gets its name because it is stratified, or layered: as elevation increases, the stratosphere gets warmer. The stratosphere increases in warmth with elevation because ozone gases in the upper layers absorb intense ultraviolet radiation from the sun.
Ozone creation and destruction
The production of ozone in the stratosphere results primarily from the breaking of the Chemical bonds within oxygen molecules (O2) by high-energy solar photons. This process, called photodissociation , results in the release of single oxygen atoms, which later join with intact oxygen molecules to form ozone. Rising atmospheric oxygen concentrations some two billion years ago allowed ozone to build up in Earth’s atmosphere, a process that gradually led to the formation of the stratosphere. Scientists believe that the formation of the ozone layer played an important role in the development of life on Earth by screening out lethal levels of UVB radiation (ultraviolet radiation with wavelengths between 315 and 280 nm) and thus facilitating the migration of life-forms from the oceans to land
Ozone Depletion
When chlorine and bromine atoms come into contact with ozone in the stratosphere, they destroy ozone molecules. One chlorine atom can destroy over 100,000 ozone molecules before it is removed from the stratosphere. Ozone can be destroyed more quickly than it is naturally created.
The breakdown of ozone in the stratosphere results in reduced absorption of ultraviolet radiation. Consequently, unabsorbed and dangerous ultraviolet radiation is able to reach the Earth’s surface at a higher intensity. Ozone levels have dropped by a worldwide average of about 4 percent since the late 1970s. For approximately 5 percent of the Earth’s surface, around the north and south poles, much larger seasonal declines have been seen, and are described as “ozone holes”. Let it be known that the “ozone holes” are actually patches in the ozone layer in which the ozone is thinner.
Solving the Problem of Ozone Destruction
The Montreal Protocol, an international agreement to address the global problem of ozone destruction, was signed by more than 70 countries in 1986. It set goals of reducing CFC production 20% by 1993 and 50% by 1998. Since the agreement was signed, these targets have been strengthened to call for the elimination of the most dangerous CFCs by 1996 and for regulation of other ozone-depleting chemicals.
Scientists detected the problem and identified the cause of the problem. Their evidence convinced governments around the world to take action to help stop the problem. The global elimination of ozone-depleting chemicals from the atmosphere will take decades, but we have made progress on filling in the hole. It was the first time in history that we tackled a global-scale environmental issue with worldwide cooperation.
“Ozone holes” are popular names for areas of damage to the ozone layer. This is inaccurate. Ozone layer damage is more like a really thin patch than a hole. The ozone layer is thinnest near the poles.
In the 1970s, people all over the world started realizing that the ozone layer was getting thinner and that this was a bad thing. Many governments and businesses agreed that some chemicals, like aerosol cans, should be outlawed. There are fewer aerosol cans produced today. The ozone layer has slowly recovered as people, businesses, and governments work to control such pollution.
