Functions of the Environment
The environment performs certain vital functions, like sustaining life. It would be able to function properly as long as the demand for these functions is within its carrying capacity. The rising population in developing nations and the affluent consumption standards of the developed nations has placed a huge stress on the environment. Resources are becoming extinct and waste is being generated beyond the absorptive capacity. As a result, we are on the threshold of an environmental crisis. Due to the overuse of renewable resources, we are compelled to spend on research and technology to explore new alternatives. Added to this are the health costs of the degraded environment, which are higher than the benefits received. Thus, the expenditure on health is also rising. Global environmental issues like global warming and ozone depletion also add up to the financial commitments of the government. These problems are not new, but the problems have escalated due to increased industrialisation and urbanisation. The need of the hour is to take effective steps at both the individual level and at the level of the governments around the globe to combat climate change and to prevent the planet. A UN conference on climate change held in Kyoto, Japan, in 1997 resulted in an international agreement to fight global warming which called for reduction in emissions of greenhouse gases by industrialised nations.
Which of the following statements defines ozone depletion?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → The phenomenon of reduction in the amount of ozone in the stratosphere.
High above the earth, in the stratosphere, a layer of ozone shields us from the sun’s ultraviolet radiation. Chlorine and bromine compounds from chlorofluorocarbons (CFCs), used in air-conditioners, refrigerators and aerosol sprays, and from halons in fire extinguishers break this ozone down. The resulting reduction in the amount of ozone in the stratosphere is ozone depletion, and it lets more ultraviolet radiation reach the earth.
Why the other options are incorrect
Option (2) The use of Chlorofluorocarbon compounds to improve the ozone layer. — Incorrect. CFCs do not improve the ozone layer; they are a main cause of its depletion.
Option (3) The effect of aquatic organisms on the atmosphere. — Incorrect. Ozone depletion is caused by man-made chemicals, not by living organisms in water.
Option (4) The increase in the average temperature of earth’s surface. — Incorrect. A rise in the earth’s average temperature is global warming, the other global environmental issue the passage names.
NCERT (2025-26): “Box 7.2: Ozone Depletion Ozone depletion refers to the phenomenon of reductions in the amount of ozone in the stratosphere. The problem of ozone depletion is caused by high levels of chlorine and bromine compounds in the stratosphere. The origins of these compounds are chlorofluorocarbons (CFC), used as cooling substances in air-conditioners and refrigerators, or as aerosol propellants, and bromofluorocarbons (halons), used in fire extinguishers.…” |