‘Sea levels are rising, but we aren’t sure why...’

Countering the popular belief that if the glaciers are melting in Antarctica, the sea level is going to rise, secretary Union ministry of earth sciences, Shailesh Nayak said on Thursday that glacial melt is only one of the three reasons for the sea level rise.

"Thermal expansion of water due to higher temperatures and tectonic change in the sea floor are the other two reasons owing to which sea levels increase," he said, delivering a lecture on Impact of Climate Change on Coastal Zone on Thursday evening.

Reiterating through scientific findings that the sea level is indeed rising at the rate of about 1.3 mm in India, at par with the global average of 1.8mm, Nayak said it was difficult to determine which of the three reasons is contributing to this steady rise. "A notable increase has been noticed on the Mumbai shore, substantial in Kochi, not too much on Vishakhapatnam and almost none on Chennai. So intense studies are required to understand the exact reasons," he said.

Further listing the impacts climate change will have on coastal areas, he said soil erosion, threat to estuarine health, mangrove and coastal wetland degradation, coral bleaching and stress on fisheries could be imperative.

However, the main concerns right now are the unknowns like what will happen to sea levels if there is excessive rainfall; or that there have been sightings of intense chlorophyll on the West Coast off Saurashtra, but one doesn't know what causes it; mapping the vulnerable areas and the world's inability to really predict 'how climate will change'.

Meanwhile, what can be done is improvement of regional monitoring of climate, better forecasting, more intense ecosystem monitoring, and development of more human resources.