From UPSC perspective, the following things are important :
Prelims level : Not Much
Mains level : Sea level rise and global warming
- Of the major ports in India, Diamond Harbour in West Bengal located at the mouth of river Hooghly has recorded the maximum sea level increase.
Freaky rise in Sea Levels
- Going by the data from the Ministry of Earth Sciences, four ports — Diamond Harbour, Kandla, Haldia and Port Blair — recorded a higher sea level rise than the global average.
- Chennai and Mumbai, recorded a sea level rise far below the global and the national averages at 0.33 mm per year (1916-2005) and 0.74 mm (1878-2005) respectively.
- Sea level rise in the country has been estimated to be 1.3 mm/year along India’s coasts during the last 40-50 years, at Diamond Harbour the rise was almost five times higher at 5.16 mm per year.
- The mean sea level rise for Diamond Harbour was based on recordings over the period from 1948 to 2005.
- This is followed by Kandla port in Gujarat where the sea level rise was 3.18 (1950 to 2005) , followed by Haldia in West Bengal, which recorded a sea level rise of 2.89 mm a year (1972 to 2005).
- Port Blair also recorded a sea level rise of 2.20 mm per year (1916-1964).
Why rise in sea level?
- Sea level rise is said be linked with global warming and as per the fifth assessment report of the International Panel on Climate Change.
- The global sea level was rising at an average rate of 1.8 mm per year over the last century.
- Global warming not only causes melting of ice and glaciers, but also leads to internal expansion of water in oceans and thus a rise in the sea level.
- Heavy rainfall and temperature extremes like heat waves and shifts in semi-arid regions were some of the recent findings which may have linkages with climate change and global warming.
- Studies over Indian region have shown a warming trend of 0.6°C on all India average basis, mainly contributed by maximum temperatures.
- The sea level rise is higher in West Bengal, particularly in the Sunderbans delta is because of the deltaic sediment deposition as a result of the mixing of fresh water and saline water, according to experts.
- Rising sea levels can exacerbate the impacts of coastal hazards such as storm surge, tsunami, coastal floods, high waves and coastal erosion in the low lying coastal areas.
- In addition it causes gradual loss of coastal land to sea.