There is an alarming rise in sea level along the Indian coast since 2004,said Shailesh Nayak,Secretary,Ministry of Earth Sciences.
Addressing the Indian Science Congress session on Weather,Climate and Environment, Nayak said the seal-level rise during 2004-08 along the Indian coast was about 9 mm. The global average sea-level rise from 1961 to 2003 was 1.8 mm per year. The annual rate along the Indian coast was faster from 1993 to 2003 and has reached about 3.1mm a year.
He said the average temperature of global oceans had increased,contributing to the sea-level rise. However,the rise in sea waters could not be attributed to global warming alone. Mountain glaciers and snow cover have declined in both hemispheres and their widespread decrease has contributed to the rising sea level,he said.
He said the rise in sea level and temperature was more or less the same across all oceans. However,the question was to what level the sea would rise. The rise of water is undulating in nature. It could come and go in a particular coast and the phenomenon would not be uniform across all seas. Along the Indian coast,the higher rise was reported from the estuary of Hooghly river. The sea erosion at Lakshadweep islands could be partly due to the rise in sea level, he said,adding that pilot project to study the phenomenon would be installed along the Chennai coast.
On earthquake and tsunami,Nayak said 70 cities in the countryincluding New Delhi and Bangalorehad been brought under earthquake mirco-zonation. Monitoring of geochemical precursors,including rising water level,was also being done in several parts of the country. He said satellite-based GPS could be used to determine whether an earthquake is strong enough to create an ocean tsunami. The current method generally underestimates large earthquakes such as the one occured in Sumatra in 2004. The GPS-based analysis can overcome this,he said.
He said widespread changes in extreme temperatures had been observed during the last 50 years. Cold days,cold nights and frost have become less frequent,while hot days,hot nights and heat waves have become more frequent. The frequency of heavy rain falls had increased over most land areas.
More intense and longer droughts had been observed over wider areas since the 1970s,particularly in the tropical and subtropical regions,he said. The need of the hour is an improved monitoring of regional climate and understanding of the regional impacts of climate change particularly,the monsoon system, Nayak said.