Ozone Layer On Track For Recovery

Context

Recently an UN-backed scientific panel has reported that the ozone ‘hole’ is now expected to be completely repaired by 2066.

Practice Question

What do you understand by depletion of ozone layer and why is it considered harmful ? Name ozone depleting substances and processes. What international conventions took place to protect the ozone layer and what was the target agreed upon? (150 words, 10 marks)

About the Highlights of the report

All these findings are reported in an UN-backed scientific panel’s report titled ‘Scientific Assessment of Ozone Depletion 2022’: 

• The ozone ‘hole’, once considered to be the gravest danger to planetary life, is now expected to be completely repaired by 2066.
• The ozone layer is the only layer over Antarctica, where the hole is the most prominent and thus will take a long time to heal completely.
• The layer is expected to return to where it was in 1980 by 2040.
• The assessment has reported that nearly 99% of the harmful chemicals banned by the Montreal Protocol have now been eliminated from use, resulting in a slow but definite recovery of the ozone layer.
• The report said that global compliance with the Montreal Protocol would ensure the avoidance of 0.5 to 1 degree Celsius of warming by 2050. 

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About the Ozone Layer

• Earth’s atmosphere has five major and several secondary layers. From lowest to highest, the major layers are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
• Ozone (chemically, a molecule having three Oxygen atoms, or O3) is found mainly in the upper atmosphere, an area called the stratosphere, between 10 - 50 km from the Earth’s surface. 
• Significance: Ozone layer is critical for planetary life since it absorbs ultraviolet (UV) rays coming from the Sun. UV rays cause skin cancer and many other diseases and deformities in plants and animals.

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Depletion of the Ozone Layer

• In the early 1980s, before climate change came, the biggest environmental threat which is the depletion of the ozone layer was first noticed over the South Pole.
• Depletion of the ozone layer is commonly referred to as the emergence of a ‘hole’ in the ozone layer, which is actually just a reduction in the concentration of the ozone molecules. 
• The layer in the stratosphere is supposed to be the thickest, it is now present in fewer concentrations in the stratosphere i.e. there are no more than a few molecules of ozone for every million air molecules.
• The ozone hole over Antarctica is the biggest during the months of September, October, and November.
• By the middle of the 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 was the chlorofluorocarbons or CFCs, that was used extensively in the air conditioning, refrigeration, paints, and furniture industries.

Reasons for the Recovery of the Ozone Layer

• The ozone hole has been steadily improving since 2000, thanks to the effective implementation of the Montreal Protocol.
• Elimination of harmful release: The recovery of the ozone layer has been made possible by the successful elimination of some harmful industrial chemicals, together referred to as Ozone Depleting Substances or ODSs, through the implementation of the 1989 Montreal Protocol.
• The Montreal Protocol was amended in 2016 to extend its mandate over hydrofluorocarbons, or HFCs, that have replaced the CFCs in industrial use. HFCs, are also powerful greenhouse gasses, but they do not cause much damage to the ozone layer. 

Can the Emission of GHG be curtailed like ODSs?

• The success of the Montreal Protocol is often offered as a model for climate action.
• However the elimination of Ozone Depleting Substances was successful but the elimination of greenhouse gasses is limited.
• ODSs’ usage is limited to specific industries thus they are easy to curtail. Their replacements are also easily available, even if at a slightly higher cost initially. 
• In the case of GHGs, almost every economic activity leads to carbon dioxide emissions, even the so-called renewable energies like solar or wind,  have considerable carbon footprints right now.
• The emissions of methane, the other major greenhouse gas, come mainly from agricultural practices and livestock. 
• Greenhouse gas emissions also have implications for the quality of life, human lifestyles, and habits and behaviors. Thus Climate change, no doubt, is a far more difficult and complex problem than dealing with ozone depletion.

News Source: The Indian Express

https://indianexpress.com/article/explained/explained-climate/ozone-hole-filling-up-now-antarctica-montreal-protocol-greenhouse-gases-climate-change-8374040/

Frequently Asked Questions

Q. Where is the ozone hole and how is it caused?

Ans. In the early 1980s, scientists using ground-based and satellite measurements began to realize that the Earth’s natural sunscreen was thinning dramatically over the South Pole each spring. 

This thinning of the ozone layer over Antarctica came to be known as the ozone hole. 

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.

Q. Is ozone hole filled now?

Ans. The ozone hole has been steadily improving since 2000, thanks to the effective implementation of the Montreal Protocol that eliminated some harmful industrial chemicals, together referred to as Ozone Depleting Substances or ODSs.

Q. Are ozone holes harmful?

Ans. The stratospheric ozone layer protects life on Earth by absorbing ultraviolet light, which damages DNA in plants and animals (including humans) and leads to sunburns and skin cancer. 

Thus increasing ozone holes are causing all these issues.

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