OZONE HOLE

1. Context

2. About Ozone Layer

• The depletion of the ozone layer, first noticed in the early 1980s, used to be the biggest environmental threat before climate change came along. Ozone (chemically, a molecule having three Oxygen atoms, or O3) is found mainly in the upper atmosphere, an area called stratosphere, between 10 and 50 km from the Earth’s surface.
• It is critical for planetary life, since it absorbs ultraviolet rays coming from the Sun. UV rays are known to cause skin cancer and many other diseases and deformities in plants and animals.
•  Though the problem is commonly referred to as the emergence of a ‘hole’ in the ozone layer, it is actually just a reduction in concentration of the ozone molecules.
• Even in the normal state, ozone is present in extremely low concentrations in the stratosphere. Where the ‘layer’ is supposed to be the thickest, there are no more than a few molecules of ozone for every million air molecules.
• In the 1980s, scientists began to notice a sharp drop in the concentration of ozone. This drop was much more pronounced over the South Pole, which was later linked to the unique meteorological conditions -temperature, pressure, wind speed and direction -that prevail over Antarctica.
• The ozone hole over Antarctica is the biggest during the months of September, October, and November.
  By the middle of 1980s, scientists had figured out that the chief cause of ozone depletion was the use of a class of industrial chemicals that contained chlorine, bromine or fluorine.
• The most common of these were the chlorofluorocarbons, or CFCs, that were used extensively in the airconditioning, refrigeration, paints, and furniture industries. 

4. Montreal protocol plays a crucial Role In Tackling Ozone Depletion

• The ozone hole has been steadily improving since 2000, thanks to the effective implementation of the Montreal Protocol. The latest scientific assessment has said that if current policies continued to be implemented, the ozone layer was expected to recover to 1980 values by 2066 over Antarctica, by 2045 over the Arctic, and by 2040 for the rest of the world.
• The elimination of ozone-depleting substances has an important climate change co-benefit as well. These substances also happen to be powerful greenhouse gases, several of them hundreds or even thousands of times more dangerous than carbon dioxide, the most abundant greenhouse gas and the main driver of global warming.
• The report said that global compliance to the Montreal Protocol would ensure the avoidance of 0.5 to 1 degree Celsius of warming by 2050. This means that if the use of CFCs and other similar chemicals had continued to grow the way it did before they were banned, the world would have been 0.5 to 1 degree Celsius warmer than it already is.
• The Kigali Amendment to the Montreal Protocol seeks to eliminate 80-90 per cent of the HFCs currently in use by the year 2050. This is expected to prevent another 0.3 to 0.5 degree Celsius of global warming by the turn of the century. 

6. Way forward

• The success of the Montreal Protocol in repairing the ozone hole is often offered as a model for climate action. It is argued that emissions of greenhouse gases can also similarly be curtailed to arrest rapidly rising global temperatures.
• The case of fossil fuels is very different. Emission of carbon dioxide is inextricably linked to the harnessing of energy. Almost every economic activity leads to carbon dioxide emissions.
• The emissions of methane, the other major greenhouse gas, comes mainly from agricultural practices and livestock.
• The impact of restraining greenhouse gas emissions is not limited to a few industries or economic sectors, but affects the entire economy, and also has implications for the quality of life, human lifestyles and habits and behaviours.
• Climate change, no doubt, is a far more difficult and complex problem than dealing with ozone depletion.

For Prelims & Mains