All this and more may be a possibility given the rise in global warming and measures to combat it at the national and international levels mired in diplomatic rigmarole.

But Prof Sudhir Chella Rajan, an expert on climate change, introduces a caveat: “The whole subject of assessing the adverse fallout of climate change is complicated and tricky. The debate is still on at the international level among experts.” Having said that, Prof Rajan, who teaches Humanities and Social Sciences at IIT Madras, agrees that there is a good possibility of pretty many things happening if current climate trends were any indication. In an exclusive interview to Express, he says one key impact of climate change may be a sharp rise in the sea level. “As much as one to two metres of rise by 2040-50 is probable and an immediate effect of the rise in sea level is salt water intrusion into the water table,” he says.

This would directly impact the availability of potable water and failure of regular monsoon rains could aggravate the trouble. Also there could be more and more unseasonal cyclones and storms.

Many of Chennai’s areas are low lying. Especially, neighbourhoods that dot the coastline of the city, including Tiruvottiyur, Royapuram, Adyar, Beasant Nagar and Thiruvanmiyur, may face real problems.

Pointing out that mass migration of people could be one of the important implications of the havoc triggered by climate change, Sudhir estimates that up to three million people close to the coastal belt and in low lying inland areas may have to leave the city to safer places.

Professor Rajan is co-author of The Suicidal Planet: How to Prevent Global Climate Catastrophe along with Mayer Hillman and Tina Fawcett and author of a Greenpeace report, Blue Alert - Climate Migrants in South Asia: Estimates and Solutions (2008) besides other research papers on climate policy.

The continuing debate

However, there is no unanimity among experts on the rise in sea levels. For example, the United Nations Inter-governmental Panel on Climate Change (IPCC) in its Fourth Assessment Report (AR4) in 2007 said that the sea level may rise by up to 59 cm by the turn of the century.

When asked for his take on it, Prof Rajan points out that the report had not taken several crucial factors into account while arriving at the assessment. “As I told you, it is difficult and a complicated debate and too technical,” he underlines adding that he is only stressing that there is a strong probability of a rise, more than what was projected previously.

In a recent report in The Guardian newspaper of London, Prof Stefan Ramstorf of the Potsdam Institute for Climate Impact Research in Germany was quoted as saying that the IPCC estimate had largely been based on the expansion of oceans from higher temperatures, rather than melt water and the impact of glaciers breaking into the sea.

Prof Eric Rignot, a senior research scientist at Nasa’s Jet Propulsion Laboratory, was also quoted as saying that new studies after the IPCC report was released had shown that melting and ice loss could not be overlooked. “As a result of the acceleration of outlet glaciers over large regions, the ice sheets in Greenland and Antarctica are already contributing more and faster to sea level rise than anticipated,” the report added.