Arctic’s Ozone Hole Closes

Why in news?

The European Union’s Copernicus Atmosphere Monitoring Service (CAMS) announced that the Arctic’s biggest ozone hole has closed.

How did it close?

• The closing of the ozone hole was because of a phenomenon called the Polar Vortex.
• [Polar vortex - A circling whirlpool of stratospheric winds]
• The Polar Vortex split allowed the ozone-rich air into the Arctic.
• The report also said that the closing is not because of reduced pollution levels due to Covid-19 lockdowns around the world.
• The hole in the North Pole’s ozone layer was detected in February, 2020.
• It had since reached a maximum extension of around 1 million sq km.

What is Ozone layer?

• Chemically, ozone is a molecule of three oxygen atoms.
• It is found mainly in the stratosphere, which is between 10 and 50 km from the earth’s surface.
• Though it is talked of as a layer, ozone is present in the atmosphere in rather low concentrations.
• Even at places where this layer is thickest, there are not more than a few molecules of ozone for every million air molecules.

What is the importance of the ozone layer?

• They perform a significant function of absorbing the harmful ultraviolet (UV) radiations from the sun.
• By absorbing UV radiation, the ozone molecules eliminate a big threat to life forms on earth.
• UV rays can cause skin cancer and other diseases and deformities in plants and animals.

What are ozone holes?

• ‘Ozone hole’ refers to a region in the stratosphere where the concentration of ozone becomes extremely low in certain months.
• South Pole - Ozone holes are most commonly found over Antarctic region than that of the Arctic region.
• They form in the months of September, October and November.
• They are formed due to a set of special meteorological and chemical conditions that arise at the South Pole.
• Here, it can reach sizes of around 20 to 25 million sq km.
• North Pole - Ozone holes over the North Pole are much smaller in size than the South Pole.
• This is due to the warmer temperatures in the North Pole.
• Before this year, the last sizable Arctic ozone hole was reported in 2011.

Why this year’s Arctic ozone hole was massive?

• The unusual atmospheric conditions, including freezing temperatures in the stratosphere, were responsible for its depletion.
• Cold temperatures (below -80°C), sunlight, wind fields and substances such as chlorofluorocarbons (CFCs) were also responsible.
• Arctic temperatures do not usually fall as low as in Antarctica.
• However, this year, powerful winds flowing around the North Pole trapped cold air within the polar vortex.
• By the end of the polar winter, the first sunlight over the North Pole initiated this unusually strong ozone depletion.
• This caused the ozone hole to form.

What is the rate of ozone recovery?

• As per the Scientific Assessment of Ozone Depletion data (2018), ozone layer in parts of the stratosphere has recovered at a rate of 1-3% per decade since 2000.
• At these projected rates, the Northern Hemisphere and mid-latitude ozone is predicted to recover by around 2030.
• The Southern Hemisphere ozone will recover by around 2050, and polar region ozone by 2060.

Source: The Indian Express