Deepening of ozone hole in Antarctica

GS Paper III

News Excerpt:

According to new research, the hole in the Antarctic ozone layer has been getting deeper in mid-spring over the last two decades, despite a global ban on chemicals that deplete Earth's shield from deadly solar radiation.

Findings and the Analysis of the new research:

  • Six of the last nine years have had really low ozone amounts and extremely large ozone holes.
  • The findings reveal the recent large ozone holes may not be caused just by CFCs.
  • Despite the decline in CFCs, there has not yet been a significant reduction in the area covered by the Antarctic ozone hole.

Ozone layer

  • The ozone layer is a region of high ozone concentration in the stratosphere, 15 to 35 kilometres above the Earth's surface. 
  • It acts as an invisible shield and protects us from the sun's harmful ultraviolet (UV) radiation.
  • It filters out most of the sun's ultraviolet radiation, which can cause skin cancer and cataracts.

What is an Ozone Hole?

  • It is a region of exceptionally depleted ozone in the stratosphere over the Antarctic that happens at the beginning of Southern Hemisphere spring (August–October).
  • The ozone hole is the region over Antarctica with total ozone of 220 Dobson Units or lower.
  • From the mid-1970s, chemicals called chlorofluorocarbons (CFCs)—once widely used in aerosols and refrigerators—were found to be reducing ozone levels, creating annual holes primarily over the Antarctica region.
  • The 1987 Montreal Protocol, which banned CFCs from closing the hole, is considered a success story for international environmental cooperation.

UN-backed assessment in January 2023

  • The assessment found that the Montreal Protocol and various agreements were working.
  • It projected the ozone layer should be restored to 1980 levels over the Antarctic by around 2066.
  • Smaller holes over the Arctic were projected to recover by 2045 and for the rest of the world in around two decades.

 Ozone hole variation Scenario in 2023:

  • The ozone hole over Antarctica usually opens in September and lasts until November, taking in the Southern Hemisphere's spring.
  • The researchers said the hole had been opening later in September, indicating a recovery possibly due to CFC reductions.
  • But in October, when the hole is often the largest, the ozone level in the middle stratospheric layer shrunk by 26 per cent from 2004 to 2022, said the study, citing satellite data.
  • The study's lead author, Hannah Kessenich emphasised that the Montreal Protocol and CFC reductions were still "on track".
  • But "altogether, our findings reveal the recent, large ozone holes may not be caused just by CFCs”.

An unusual few years:

  • The years from 2020 to 2022 can be regarded as an unusual few years.
  • 2020's ozone hole was made 10 per cent wider by Australia's massive "Black Saturday" wildfires.
  • The gigantic eruption of the Hunga-Tonga-Hunga-Ha'apai volcano off Tonga in 2022 is also believed to have affected recent ozone levels.

However, the study's results did not convince Martin Jucker, an expert at Australia's University of New South Wales. He said, "It is questionable how the authors can remove 2002 and 2019 from the record but not 2020-22, given that all of these years have been shown to be dominated by very special and rare events,"

Initiatives taken to tackle Ozone hole depletion:

  • Montreal Protocol: It is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances responsible for ozone depletion. It was agreed on 16 September 1987 and entered into force on 1 January 1989.
  • Amendment to Address HFCs under the Montreal Protocol: Under the amendment, developed countries will reduce HFC consumption beginning in 2019. Most developing countries will freeze consumption in 2024, with a few developing countries with unique circumstances freezing consumption in 2028.

Prelims PYQ

Q. Which one of the following is associated with the issue of control and phasing out of the use of ozone-depleting substances? (UPSC 2015)

(a) Bretton Woods Conference

(b) Montreal Protocol

(c) Kyoto Protocol

(d) Nagoya Protocol


Q. The formation of ozone hole in the Antarctic region has been a cause of concern. What could be the reason for the formation of this hole? (UPSC 2011)

(a) Presence of prominent tropospheric turbulence; and inflow of chlorofluorocarbons

(b) Presence of prominent polar front and stratospheric': Clouds; and inflow of chlorofluorocarbons

(c) Absence of polar front and stratospheric clouds; and inflow of methane and chlorofluorocarbons

(d) Increased temperature at polar region due to global warming.