New Delhi: Human-driven climate change is increasing iodine emissions in the Arctic. This, in turn, could play a bigger role in destroying the ozone layer in the troposphere – the atmospheric region closest to Earth’s surface – above the North Pole than previously thought, an international team of researchers has found.
studyBased on observations made from March to October 2020 on a research vessel in the high arctic region, was published in the journal nature geology on 15 September 2022.
In the stratosphere – the second layer of the atmosphere, above the troposphere – ozone depletion has been widely reported. However, in the troposphere, similar, but short-lived, depletion events are also observed close to the Earth’s surface.
During these depletion events, ozone concentrations drop to nearly zero. This phenomenon, the subject of study, is known as springtime troposphere ozone depletion.
Anoop Mahajan, a scientist at the Indian Institute of Tropical Meteorology in Pune and one of the study’s authors, told ThePrint that the halogens – such as bromine, chlorine and iodine – act as catalysts in a reaction that causes the breakdown of ozone. (O3) to oxygen (O2).
Ozone depletion events near Earth’s surface were previously thought to be primarily due to catalytic reduction by a type of halogen – bromine, which is emitted into the atmosphere from the Arctic sea-ice region.
halogen compound Overpower Salt content of sea water. When water freezes, these salts separate and form a layer on top.
But Mahajan explained that it is specifically the bromine salts that are obtained in this form and subsequently interact with the atmosphere.
On the other hand, research has shown that for iodine – naturally present in the ocean – to interact with the atmosphere, the ice caps must first melt.
“Most of the sea in the Arctic is covered by ice, reducing iodine emissions in the region. However, with global warming induced by rapid climate change, more and more seawater in the Arctic region is exposed to the atmosphere,” said Mahajan. explained.
Ozone near the Earth’s surface then rapidly reacts with the now exposed iodine on the ocean surface. It is believed that this conversation largest single source Gaseous iodine emissions into the atmosphere, which then leads to tropospheric ozone depletion in the spring.
Read also: West Antarctica glacier is disintegrating faster than thought
link to climate change
Using a chemical model, the researchers showed that chemical reactions between iodine and ozone are the second largest contributor to the loss of surface ozone, after ozone photolysis (the decomposition of molecules due to light) and further damage from bromine.
According to the research team, this arctic photochemical turns a decades-old paradigm shift on the drivers of ozone loss.
With increased iodine emissions, as well as Arctic sea-ice thinning and shrinking expected in the near future, these results indicate that iodine chemistry may play an increasingly important role in the future. This should be taken into account to accurately quantify the ozone budget in the Arctic, the study said.
But unlike ozone in the stratosphere – which helps protect Earth from harmful radiation from the Sun – ozone in the troposphere is a pollutant that can harm human health.
Asked why ozone depletion in the troposphere is a concern, Mahajan explained that every chemical process that occurs is important for understanding the overall effects of climate change.
“Understanding these chemical reactions will help us build better predictive models that can tell us more about the future with better accuracy,” he said.
(Edited by Therese Sudeep)
Read also: Japan, Puerto Rico witness torrential rains, massive blackouts as deadly cyclones pound nations