World Ozone Day, held on September 16, celebrates collective decisions and actions, guided by Science, as a way to solve major global crises. “The slogan Ozone for Life reminds us of how Ozone proves to be crucial, for life on earth, and that we must continue to protect the Ozone layer for our future generations”, according to an article published for this day at un.org website.
This day, back in 1987, the Montreal Protocol was signed with a principal aim to safeguard the Ozone layer. In 1994, The United Nations General Assembly proclaimed 16th September as the International Day for the preservation of the Ozone layer or the World Ozone Day.
Why does the UN mark International Days?
International days are such occasions where we can educate the masses on issues of concern (be it environmental, or issues of health, etc. to mobilize political will and resources to address such global problems, and also to celebrate and reinforce achievements of humanity. International Days are marked and celebrated since before the UN was established, but the UN has found a powerful tool in them.
The Montreal Protocol:
Protocols are official procedure or system of rules governing affairs of state or diplomatic occasions. The Montreal Protocol came into force on January 1, 1989.
A declaration was made by the Holy See [The Roman Catholic Church was elected to participate as a permanent observer state to UN as “The Holy See”] to encourage the entire International Community to be resolute in promoting authentic cooperation between politics, science, and economics. Such cooperation, as has been shown in the case of the ozone regime, can achieve important outcomes, which make it simultaneously possible to safeguard creation, to promote integral human development, and to care for the common good, in a spirit of responsible solidarity and with profound positive repercussions for present and future generations.
FACTS WE SHOULD KNOW :
- OZONE DEPLETION:
The initial step in the depletion of stratospheric ozone by human activities is the emission, at Earth’s surface, of gases containing chlorine and bromine. Most of these gases accumulate in the lower atmosphere because they are unreactive and do not dissolve readily in rain or snow. Natural air motions transport these accumulated gases to the stratosphere, where they are converted to more reactive gases. Some of these gases then participate in reactions that destroy ozone. Finally, when air returns to the lower atmosphere, these reactive chlorine and bromine gases are removed from Earth’s atmosphere by rain and snow.
- WHAT CAUSES THIS DEPLETION?
Certain industrial processes and consumer products result in the emission of ozone-depleting substances (ODSs) to the atmosphere. ODSs have manufactured halogen source gases that are controlled worldwide by the Montreal Protocol. These gases bring chlorine and bromine atoms to the stratosphere, where they destroy ozone in chemical reactions. Important examples are the chlorofluorocarbons (CFCs), once used in almost all refrigeration and air conditioning systems, and the halons, which were used in fire extinguishers. Current ODS abundances in the atmosphere are known directly from air sample measurements.
- WHY HAS AN “OZONE HOLE” APPEARED OVER ANTARCTICA WHEN OZONE-DEPLETING SUBSTANCES ARE PRESENT THROUGHOUT THE STRATOSPHERE?
Ozone-depleting substances are present throughout the stratospheric ozone layer because they are transported great distances by atmospheric air motions. The severe depletion of the Antarctic ozone layer known as the “ozone hole” occurs because of the special meteorological and chemical conditions that exist there and nowhere else on the globe. The very low winter temperatures in the Antarctic stratosphere cause polar stratospheric clouds (PSCs) to form. Special reactions that occur on PSCs, combined with the isolation of polar stratospheric air in the polar vortex, allow chlorine and bromine reactions to produce the ozone hole in Antarctic springtime.
- IS DEPLETION OF THE OZONE LAYER THE PRINCIPAL CAUSE OF GLOBAL CLIMATE CHANGE?
No, ozone depletion itself is not the principal cause of global climate change. Changes in ozone and climate are directly linked because ozone absorbs solar radiation and is also a greenhouse gas. Stratospheric ozone depletion leads to surface cooling, while the observed increases in tropospheric ozone and other greenhouse gases lead to surface warming. The cooling from ozone depletion is small compared to the warming from the greenhouse gases responsible for observed global climate change.
- HOW IS OZONE EXPECTED TO CHANGE IN THE COMING DECADES?
Substantial recovery of the ozone layer from the effects of ozone-depleting substances (ODSs) is expected near the middle of the 21st century, assuming global compliance with the Montreal Protocol. Recovery will occur as ODSs and reactive halogen gases in the stratosphere decrease in the coming decades. In addition to responding to ODSs, future ozone amounts will increasingly be influenced by expected changes in climate. The impacts of future climate change on the ozone layer will vary between the tropics, midlatitudes, and polar regions, and strongly depend on future emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). During the long recovery period, large volcanic eruptions could temporarily reduce global ozone amounts for several years.
Original Source of the Article: Scientific Assessment of Ozone Depletion:2014
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