The ozone hole
Ozone Layer May Be on the Mend
Damage to the ozone layer, caused by chlorofluorocarbon (CFC) chemicals and other pollutants, may be starting to reverse itself according to data collected by NASA satellites.
While ozone degradation continues despite global bans on ozone-depleting pollutants imposed more than a decade ago, the rate has slowed markedlyenough in one layer of the atmosphere that scientists belive ozone could start to be replenished there within several years.
Enormous Ozone Hole
Though ozone is only present in tiny quantities in the Atmosphere, it is essential to life, as it absorbs harmful Ultraviolet (UV-B) light. The ozone layer cuts out up to 95 Percent of the sun's UV-B radiation. Increases in skin cancer cases have been recorded in parrarel with ozone depletion. UV-B rays can also cause cataracts and damage crops. The majority of atmospheric ozone (the „ozone layer”) is found in the stratosphere, the region of the atmosphere found six miles (ten kilometers) above the Earth's surface and Beyond.
In the mind-1970s, Scientists first noticed that chlorine produced in the atmosphere from human-made CFCs and similar chemicals had the potential to destroy ozone and damage the ozone layer. CFCs were previously used in refrigerators, fire extinguishers, air conditioners, and as aerosol propellants in a wide-range of spray can consumer products, from paint to deodrant to hair spray. Observations then showed that CFC chemicals were building up in the atmosphere and that the ozone layer was thinning.
The most dramatic discovery came in the mind-1980s: Scientists with the British Antarctic Survey discovered the enormous ozone hole which appears sesonally, exposing the entire Antarctic continent to levels of ultraviolet radiation many times greater than natural levels. As a result of these findings, and their grave implications, governments came together to produce the 1987 United Nations Montreal Protocol. This treaty and subsequent amendments led to the development of replacement chemicals, And a near-total ban on the use of CFCs and related chemicals.
Reductions in CFCs and chlorine observed at ground level during the 1990s led Newchurch and his team to reassess the effect of these chemicals on the upper stratosphere, the region from 22 to 28 miles (35 to 45 kilometers) above Earth's Surface. Though most ozone is found in the lower stratosphere, the region from 6 to 22 miles (10 to 35 kilometers) above the Earth, ozone depletion in the upper stratosphere is more closely linked to chlorine chemistry alone. As a result, scientists anticipated that reduced CFC levels and Increased ozone levels tied he effect of the global CFC ban would be first observed in the upper stratosphere. The results showed that between 1979 and 1997 ozone diminished at a rate of eight percent each decade in upper stratosphere. However, between 1997 and 2002, the rate of depletion slowed to a projected average of just four percent per decade. The results showed that between 1979 and 1997 ozone diminished at a rate of eight percent each decade in upper stratosphere. However, between 1997 and 2002, the rate of depletion slowed to a projected average of just four percent per decade.
Nasa Photographs Huge Clouds of Pollution Over Earth
The U.S. National Aeronautics and Space Administration (NASA) has assembled the most Comprehensive view of air pollution in the Earth's atmosphere to date. Images from NASA's Terra spacecraft offer new ways to locate, identify, and track major sources of air pollution on Earth.
The spacecraft's initial observations reveal expansive clouds of carbon monoxide and other air pollutants spreading over continents and oceans worldwide. The major sources of these pollutants include natural air pollution from forest and grassland fires as well as human-based emissions from fossil-fuel burning. The first MOPITT observations are being released at the Annual American Geophysical Union spring meeting in Boston.
When Air Can Kill
The air was so murkly that drivers had to use headlights in the middle of the day. Afflictions of the industrial age, air and water pollution rank among the most vexing examples of the law of unintended consequences. In trying to make the world more livable, humans have succeeded in fouling not only their own nests but also those of many fellow creatures. The poisons in the air include nitrogen dioxide, sulfur dioxide, carbon monoxide, soot, lead, and ground-level ozone. The result was the worst air pollution disaster ever recorded. A partner-in-crime of air pollution, acid rain-widely blamed on Industrial emissions-has eroded bulidings, harmed crops and forests, and threatened life in freshwater lakes.
The poisons in the air include Nitrogen dioxide, sulfur dioxide, carbon monoxide, soot, lead, and Ground-level ozone. The result was the worst air pollution Disaster ever recorded. The good news is that U.S. Emissions of most air pollutants have been dropping during the past Three decades. Unfortunately, in Many eveloping countries they are Rising at precipitous rates.