Halogens

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Context

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.

Halogens

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.