Antarctic Current Affairs - 2019
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According to US and European scientists, the extent of sea ice at both poles has hit new record lows for this time of the year.
The disappearing sea ice comes as the Earth marks three consecutive years of record-breaking heat and temperature rise, raising fresh concerns about the accelerating pace of global warming.
- Artic region: The ice floating in the Arctic Ocean grows and shrinks on a seasonal cycle every year, reaching its largest size in March and smallest at the end of the summer melt in September.
- But this year’s Arctic maximum spanned 14.42 million sq.km i.e. 95,829 sq.km below the previous record low in 2015. This year’s ice cover is 12,19,884 sq.km smaller compared to average sea ice extent for 1981-2010.
- The Arctic sea ice maximum has dropped by an average of 2.8% per decade since 1979. There was a lot of open ocean water and very slow ice growth because the water had a lot of accumulated.
- Antartic region: The ice in the Antarctic also follows a seasonal cycle but its maximum comes in September and its minimum around February (summer in Southern Hemisphere).
- In the Antarctic, this year’s annual sea ice was 21,10,840 sq.km, about 1,83,889 sq.km below the previous lowest minimum extent in the satellite record, which occurred in 1997.
- For the past two years, Antarctica saw record high sea ice extents and decades of moderate sea ice growth.
Scientists for the first time have found clear evidence that the thinning in the ozone layer above Antarctica is starting to heal.
Ozone layer in the atmosphere’s stratospheric layer comprises of Ozone (O3), an allotrope of oxygen. It plays important role in blocking harmful ultraviolet radiation (UV) from the Sun.
The absence or thinning of Ozone layer increases the chances of skin cancer, cataract damage in human beings and even causes harm to animals and plants.
- In the research, scientists have found that ozone hole was around 4 million square kilometres in September 2015, smaller than it was in the year 2000.
- It was based on detailed measurements of the amount of ozone in the stratosphere between 2000 and 2015.
- These measurements were based on data obtained from weather balloons, satellites and model simulations.
- The healing of ozone layer was due to the long term phasing out (banning) of ozone-destroying chemicals (ODCs) such as chlorofluorocarbons (CFCs) in Montreal Protocol 1987.
- More than half the shrinkage of ozone hole was due solely to the reduction in atmospheric chlorine.
- However, it has found that on the role of volcanoes in thinning of the ozone layer is making the problem worse.
For more details: (i) Depletion of Ozone Layer (ii) Antarctic Ozone hole (iii) Is Ozone hole over only Antarctica?