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The recently published report of the Indian Institute of Tropical Meteorology said that halogens' contributions to cooling the environment could increase to 18-31 per cent by 2100.

Key findings of the report:


  • Oceans along with absorbing carbon dioxide and moderating the climate also cool the planet by releasing short-lived halogens such as chlorine, bromine and iodine
  • The short-lived halogens from the ocean reduce warming by depleting ozone.
  • They increase methane’s lifetime in the atmosphere by destroying hydroxyl radicals (OH).
  • They have increased the global methane burden by 14 per cent and 9 per cent for pre-industrial and present-day conditions.
  • Halogens increase the levels of water vapour, a greenhouse gas in the atmosphere.
  • The emission of halogen from the ocean is not the same across the world.
  • Over continents, the emissions are small while it is bigger in polar regions and some places with higher ozone levels.


Key facts about Halogens:

  • The term Halogen in Greek means salt-producing because it reacts with many metals to produce salts. 
  • They are a group of elements located in Group 17 of the periodic table which includes fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).
  • In 1826, Swedish chemist Jons Berzelius coined the term halogen for the entire group of elements. 
  • Unlike metals, they exist in all three different states of matter in their standard state.
  • For example, fluorine is found naturally as a gas, bromine as a liquid, and the larger iodine is found naturally as a solid.
  • Reactivity: Halogens are the most reactive nonmetals on the periodic table and are powerful oxidizing agents.


Q1) What is GHG?

GHG stands for greenhouse gas. These are gases that trap heat in the Earth's atmosphere, leading to the greenhouse effect and contributing to global warming and climate change.

Source: Oceans cool the planet by releasing short-lived halogens that contribute 8-10 per cent of cooling: Study