Heat trapped in the atmosphere due to rising sea levels makes water expand.
Melting ice sheets begin to add water to the world’s oceans.
NASA’s satellite data shows that the seas on average have risen 85 mm since 1993, adding about 3.5 mm annually.
What is peculiar about the Indian Ocean?
The Indian Ocean has been rising rapidly, particularly since 200.
It was specific to a smaller stretch called the North Indian Ocean, which consists of the Bay of Bengal, the Arabian Sea and a large part of the Indian Ocean until the 5 degree S latitude.
North Indian Ocean sea levels actually dipped between 1993 and 2004, at about 0.3 mm per year, but after 2004, the rise was 6 mm annually.
Such a fluctuating trend hasn’t been observed for the Pacific Ocean and the Atlantic Ocean.
Why did this happen?
The North Indian Ocean is surrounded by land on all sides, except an outlet on the southern side.
This influences the rate at which heat is absorbed and flushed out from within the system.
Wind flows, which led to warm water welling up on the Indian Ocean surface, changed directions every decade and probably influenced sea level patterns.
What does this imply?
This means a rise in average global temperature doesn’t mean a concurrent rise in sea levels everywhere.
Every year in the last decade has broken temperature records that have held for over a century.
But researchers believe that North Indian Ocean levels may see a fall over the next decade (like seen between 1993 and 2004).
What should be done?
These points to a need for more research to understand the inherent variability of the Indian Ocean.
This could help sharpen monsoon forecasts and predicting coastal erosion patterns.
Better understanding of sea level undulations could also inform future reports by the Intergovernmental Panel on Climate Change.
