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International Ozone Day

  May 28, 2020

International Ozone Day

International Ozone Day - September 16

The United Nations International Day for the Preservation of the Ozone Layer is observed every year on September 16. 

What are the atmospheric layers?

Earth is surrounded by an atmosphere which comprises five layers held together by gravity. They include the troposphere, the stratosphere, the mesosphere, the thermosphere and, finally, the exosphere as we move up. Each layer has its own role in protecting Earth and supporting life on the planet. Our focus is on the second layer – the stratosphere. It is the most stable region, where jets fly. It is also the region where ozone, a gas made of three oxygen atoms (O3), is abundant.

What is ozone?

Ozone (O3) is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in the Earth's upper atmosphere (the stratosphere) and lower atmosphere (the troposphere). Depending on where it is in the atmosphere, ozone affects life on Earth in either good or bad ways.

What is ozone hole?

Ozone hole refers to an area in the atmosphere where the amount of ozone present is less than 220 Dobson units. The Dobson unit that measures the total amount of ozone in the atmosphere is named after G.M.B. Dobson, the British weather scientist, who first measured its thickness.

The recurring springtime Antarctic ozone hole was first reported in a study in 1985 which triggered debates about pollution, ultraviolet rays and humans’ role in the depletion of ozone. It also brought together all nations to commit themselves to phase out ozone-depleting agents.

What is springtime depletion and why does it take place in sprint?

Every year, the ozone levels over Antarctica sink drastically during the Southern Hemisphere's spring. Scientists believe this began happening in the late 1970s as a result of CFCs. The hole forms in the Antarctic because cold air becomes trapped there as a result of the polar vortex -- strong, circulating winds. The cold temperatures allow the formation of polarstratospheric clouds (PSCs), or ice clouds. These PSCs are conducive to the breakdown of chlorine-containing compounds, which are there because of our production of CFCs. This makes the area especially susceptible to ozone depletion. When sun strikes PSCs in early spring, large amounts of chlorine monoxide form from the substances that contain chlorine. By early summer, ozone from other areas comes in to help fill this hole. But because of our CFC production, the hole returns each year.

Why is it important?

The region in the stratosphere that contains relatively higher concentration of ozone (in comparison to the other parts of the atmosphere) is called the ozone layer. This layer, found about 10 to 40 km above the ground, acts as a shield absorbing most of the sun's ultraviolet radiation. It protects life on Earth from the harmful effects of UV rays.

What causes the depletion?

Ozone depletion occurs when chlorofluorocarbons (CFCs) and halons — gases found in aerosol spray cans and refrigerants — are released into the atmosphere.

Other ozone depleting chemicals include carbon tetrachloride and trichloroethane. Anaesthetics, firefighting equipment and manufacture of materials such as styrofoam also release these substances. These chemicals can remain in the atmosphere for decades to over a century.

What has India contributed to the phaseout?

India signed and ratified the Vienna Convention for the Protection of the Ozone Layer in 1991 and the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987, signalling the country’s commitments to the global cause of addressing the harmful effects of the ozone layer depletion. India completely phased out production and consumption of Chlorofluorocarbons, carbon tetrachloride and halons, man-made chemicals responsible for the depletion of the Ozone Layer. This remarkable milestone was achieved two years ahead of schedule.

Has the ozone been restored?

In 2018, the four-yearly review of the Montreal Protocol, a 1987 ban on man-made gases that damage the fragile high-altitude ozone layer, found long-term decreases in the atmospheric presence  of ozone-depleting substances and the ongoing recovery of stratospheric ozone.The Antarctic ozone hole is expected to gradually close, returning to 1980 levels in the 2060s.The ozone layer that shields life from cancer-causing solar rays is recovering at a rate of one to three percent per decade, reversing years of dangerous depletion caused by the release of harmful chemicals.

So the Montreal Protocol worked?

The Antarctic ozone hole is recovering, while continuing to occur every year. As a result of the Montreal Protocol much more severe ozone depletion in the polar regions has been avoided.

Evidence shows that the ozone layer in parts of the stratosphere has recovered at a rate of 1-3 percent per decade since 2000.At projected rates, Northern Hemisphere and mid-latitude ozone is scheduled to heal completely by the 2030s followed by the Southern Hemisphere in the 2050s and polar regions by 2060.

The U.N. had already hailed the success of the Protocol, which banned or phased out ozone depleting chemicals, including chlorofluorocarbons (CFCs) once widely used in refrigerators and spray cans. The report said it was the first time that there were emerging indications that the Antarctic ozone hole had diminished in size and depth since 2000.

What about the Arctic?

In the Arctic, annual variations were much larger, making it hard to confirm whether there had been a definite recovery in the layer since 2000.

Why did the report talk of CFC-11?

While most of the banned gases have been phased out, the report found at least one violation of the protocol: an unexpected increase in production and emissions of CFC-11 from eastern Asia since 2012. The report said the source country or countries had not yet been identified.If CFC-11 emissions continued at the same rate, return of mid-latitude and polar ozone-depleting chemicals to their 1980 values would be delayed .

What is Kigali Agreement? Why was it necessary? When did it come into force? How will it help?

The Kigali Amendment to the Montreal Protocol on Substances that Deplete the Ozone Layer entered into force on 1 January 2019, following ratification by 65 countries including India. The UN Environment Programme (UNEP or UN Environment) announced the entry into force, and noted that it will help reduce the production and consumption of hydrofluorocarbons (HFCs), potent greenhouse gases (GHGs), and thus to avoid global warming by up to 0.4°C this century.

The need for the Amendment emerged from the 1987 Montreal Protocol process, which controls ozone-depleting substances. With HFCs’ use as an alternative to ozone-depleting substances in cooling equipment, their role in warming the atmosphere became a greater concern. In 2016, the Parties to the Montreal Protocol adopted the agreement on HFCs at the close of the 28th Meeting of the Parties (MOP 28) in Kigali, Rwanda. 

Under the Amendment, all countries will gradually phase down HFCs by more than 80 percent over the next 30 years and replace them with more environmentally friendly alternatives. A specified group of developed countries will begin the phase-down in 2019. Several developing countries will freeze HFC consumption levels in 2024, followed by additional countries in 2028. The Amendment also includes agreements on technologies to destroy HFCs, data reporting requirements, and provisions for capacity building for developing countries.