Midya’s work throws new light

A group of scientists collating global data on the depletion of the ozone layer in a small Bengal town has challenged the very basis of landmark climate change theories and policy initiatives like the Montreal and Kyoto Protocols. The group argues that chlorofluorocarbons (CFCs) are not the demons they are made out to be when it comes to depletion of the life-protecting ozone layer. There’s a bigger devil — nitrous oxide — whose damaging effects on the layer are far more severe than all greenhouse gases put together: a fact thus far neither acknowledged nor considered in any of the international conventions on climate change. In fact, the Intergovernmental Panel on Climate Change (IPCC) mentions N2O only in the list of a greenhouse gas relevant to radiative forcing and not in the list of ozone-depleting gases. The conclusion, which the group published in the Indian Journal of Physics six years back, has gone unnoticed by the global environment community. Dr S K Midya of the department of physics at Serampore College in Hooghly district of West Bengal and his team are set to do just that — make the world sit up and take note.

Writing in the journal in June 2000, Midya and his peers S C Ganda and S N Sahu from the department of zoology at Kalyani University in Bengal’s Nadia district, had shown that nitrous oxide (N2O) contributed over 61.67 per cent to the depletion of the ozone layer. The contribution of carbon dioxide and CFCs: 27 per cent and about seven per cent, respectively. Midya and his colleagues had made the inference from data emanating from the Antarctic Survey Station Mc Murdo and made available on the Internet. They have used the standard atmospheric dynamic model and statistics from Mc Murdo to create a statistical model that calculated unknown parameters like the constituent density of the gases in question. “The world still believes that CFCs were the biggest criminals. But our study shows they are very small contributors to the process of depletion. Nitrous oxide seems to be the key depleting agent,” Midya says.

The paper titled Percentage contribution of different stratospheric compounds on depletion of ozone at Antarctica has been acknowledged as “very good” by leading environment scientists. But they are asking the following questions:

Why have scientists at the primary source of information, McMurdo, not reported this all these days?

Why did this group take so long to come out with it in the open?

Why haven’t they estimated the levels of other nitrous gases NO and NO2 while making their calculations?

Midya, who has 76 scientific papers to his name in this area of specialisation, says the statistical model they used was the key to calculating the data coming out of McMurdo. Nitrous oxide, a by-product of many fertilisers and factories, is more reactive in ozone chemistry than other oxides of nitrogen. “Though the data were gathered in 2000, they are still relevant as they point out the harmful effects of N2O for the first time, a fact increasingly acknowledged by scientists studying the phenomenon globally. In fact, the Indian Institute of Technology, Kanpur, is also conducting a study suspecting that nitrous oxide is the major culprit.”

Midya’s team also reported for the first time in 2001 the comparative ozone layer depletion levels in eight cities in India. The group recently established the link between ozone layer depletion and lack of monsoon rains in particular pockets. Their paper has been accepted by a national science journal and is awaiting publication.