Posts Tagged ‘ozone depletion effects’

Ozone Depletion

February 27, 2020

An Environmental Crisis-Ozone Depletion

ozone depletionThe continent size hole in Earth’s ozone layer is precariously identical to an ailment that takes more time to heal if treatment is delayed. Much of the protective layer of stratospheric ozone above Antarctica has gradually disappeared creating what is commonly known as the ozone hole. The Antarctic hole now measures about 9 million square miles, nearly the size of North America. Moreover, a momentous depletion of Ozone levels has been recorded around the globe. Because of reduced ozone levels, more ultraviolet radiation reaches Earth. It does not only cause more skin cancer and eye damage but also harms crops.

The Real Culprit

Scientists have found that it is chlorine that creates the hole by devouring ozone molecules. The source of the chlorine is chlorofluorocarbons CFCs; man-made chemicals.

Ozone and the crucial role that it plays:

Ozone, a relatively simple molecule, consists of three oxygen atoms bound together. Yet it has dramatically different effects depending upon its location. It displays a destructive side near Earth’s surface where it comes into direct contact with life forms. Ozone reacts strongly with other molecules. Thus the large concentration of ozone near the ground proves toxic to living things. However, 90 percent of our planet’s ozone resides at higher altitudes, where, it does a remarkable job of absorbing ultraviolet radiation. The harmful radiation has a perfect portal in the absence of this gaseous shield in the stratosphere, through which to strike Earth.

The role played by science to understand the problem:

The graph plotting the scientific discoveries concerning Ozone depletion and its damaging effects is not a straight one but full of twists and turns. Investigators did not set out to determine whether human activity affects our environment nor did they know much about chemical pollutants. Instead, they began with basic questions about the nature of Earth’s atmosphere its composition, density, and temperature distribution.

Researchers faced a major stumbling block; virtually all gases, except for molecular nitrogen and oxygen, exist in such minute concentrations that available equipment could not detect them.

Mare research led to a precise method of identifying a compound by recording a special kind of chemical fingerprint; the particular pattern of wavelengths of light it emits or absorbs. Scientists call this pattern a spectrum. Further development produced a spectrometer that could measure small concentrations of ozone. Then scientists started paying attention to find out why, how and by whom Ozone depletion takes place. Very quickly CFC was identified as the culprit.

In 1972 Rowland, joined by Mario Molina, a colleague at the University of California, Irvine, decided to find out the harm caused by CFCs a refrigerant to the environment.

At altitudes above 18 miles, with 99 percent of all air molecules lying beneath them, CFCs show their vulnerability. At this height, the harsh, high energy ultraviolet radiation from the sun impinges directly on the CFC molecules in the stratosphere, breaking them apart into chlorine atoms and chlorine oxide radicals.

Since 1987, more than 150 countries have signed the Montreal Protocol (an international agreement). Modifications of that treaty called for a complete ban of CFCs with effect from January 1996. But chlorine from CFCs will continue to exist in the atmosphere for another decade despite the fact that the ban in effect. It may take until the middle of the next century for ozone levels in the Antarctic to return to 1970s levels.

Because of the extensive research that led to early recognition of the problem and steps that have been taken to address it, the potential consequences are much less severe than they otherwise would have been. More globally, but thanks to the scientists estimate, for example, that if active research in stratosphere chemistry had not been in place at the time the ozone hole was discovered in 1985, global ozone depletion, measuring 4 percent today, would be close to 10 percent in 10 years. Even larger ozone depletion would have been observed over the United States and Eastern Europe, thanks to the research, these larger losses have been avoided because basic research in the atmospheric sciences has already advanced to a level where it was able to explain the chemical reactions occurring in the ozone layer. That knowledge allowed other informed political and regulatory decisions to be made.

Finally:

The Royal Swedish Academy of Sciences awarded Rowland, Molina, and Crutzen the Nobel Prize in Chemistry for showing how sensitive the ozone layer is to the influence of anthropogenic emission of certain compounds in 1995. In explaining the chemical mechanisms that affect the thickness of the ozone layer, the three researchers have contributed to our salvation from a global environmental problem that could have catastrophic consequences the Academy noted.

As lawmakers and the public face new challenges in the struggle to protect the environment, they will increasingly rely on basic research to open new vistas and suggest new solutions about these pressing concerns.