IAS Gyan

Daily News Analysis


1st July, 2023 Environment

Disclaimer: Copyright infringement not intended.


  • A new study published in journal Nature found that Ocean release naturally produced short-lived halogens like chlorine, bromine and iodine which contribute to 8-10 % cooling of this planet.
  • By 2100, there is a possibility that this cooling could increase to 18-31 %.

Other Details

  • Oceans perform variety of functions for wellbeing of this planet which includes absorbing carbon dioxide, moderating the climate and cooling the planet.
  • Substantial impact of short-lived halogens, with a lifetime of less than six months in the atmosphere, in cooling the planet can’t be ignored as climate models for future prediction do not account for these.


  • The name halogen is derived from words having Greek roots -
    • Hal - salt and
    • gen - to produce
  • These are non-metallic elements which constitute Group 17 (Group VIIa) of the periodic table.
  • These elements include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At) etc.
  • These elements produce sodium salts of similar properties for instance – NaCl (common table salt).

Reasons for Halogen release by Ocean

  • Naturally released by Oceans.
  • Human activities may accelerate it –
    • Pollutants like ozone are deposited on the ocean due to increased anthropogenic activities.
    • It makes hard for ocean to dissolve halogens as they become insoluble.
    • These halogens are forced out of sea water and released into the atmosphere.

Study and findings

  • Initially study was focussed on to find out the depletion of ozone in the troposphere by Halogens.
  • They considered solar radiation emitted by the sun and Earth’s terrestrial radiation to find out global radiative balance across pre-industrial, present-day and future climates.
    • Ozone is a greenhouse gas which contributes to warming.
  • It was found that short-lived halogens from oceans reduce warming by depleting ozone.
  • They also studied the methane and water vapors too but it was observed that halogens destroy hydroxyl radicals and increase the lifespan of this methane greenhouse
  • Also the similar effect was seen on water vapours.
  • Formation of cooling aerosols was also declined by halogen.
  • However these halogens destroy ozone leading to an overall net cooling effect on climate.
  • These halogen emissions are found more in polar regions.

Must Read Article:

Global Warming in Indian context


WMO report on state of Climate



Halogens. Released from oceans, are found to have a cooling effect on climate. They do so by -

1. Decreasing the concentration of Methane.

2. Increasing the rate of Ozone depletion.

3. Reducing the formation of cooling aerosols

How many of the statements given above is/are correct?

A. Only one

B. Only two

C. All three

D. None

Answer: (A)