City-based scientist Gufran Beig said the Earth’s protective ozone layer is on track to recovery in the next few decades. He, however, predicted depletion in the thickness of the layer over the tropical region which could pose considerable trouble for countries like India.
The United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) recently published a summary of an upcoming report, the Scientific Assessment of Ozone Depletion 2014 and Beig, who is the programme director of system of air quality forecasting and research at Pune-based Indian Institute of Tropical Meteorology, was a member of the review panel of the report.
“There are positive indications that the ozone layer is well on track to recovery towards the middle of the century. The Montreal Protocol - one of the world’s most successful environmental treaties - has protected the stratospheric ozone layer and avoided enhanced ultra violet radiation reaching the earth’s surface,” Beig said.
However, the report has also predicted significant decrease in column ozone (the thickness of the ozone layer) in the tropical region in 21st century. This could spell trouble for a country like India, he added.
He pointed out three main challenges that could impact the ozone layer over the tropical region - increase in green-house gases, increase in aerosols and increase in ozone concentration in the lower levels of the atmosphere.
“Tropical ozone levels are most sensitive to circulation changes driven by greenhouse gases like carbon-dioxide, nitrous-oxide and methane. There is a specific occurrence called the Brewer-Dobson circulation phenomenon which causes a concentration of gases like nitrous-oxide in the tropical region. This would seriously threaten ozone layer in this region,” he said.
In developing countries aerosol levels were increasing as compared to other countries and this naturally poses a threat to the ozone layer, he added.
While the presence of the ozone layer in the stratosphere is very useful for protecting the earth from harmful ultra violet radiation, it is important to note that the presence of ozone in the lower layer of the atmosphere is harmful for humans. It also acts like a greenhouse gas, Beig pointed.
“In the tropical region, the concentration of ozone in the troposphere has been increasing by 0.5% to 1% every year. Such an increase could cause major havoc by the end of the century,” he said.
