Indian Ocean sea levels rising twice as much as other oceans

Vasco: Sea levels in the Indian Ocean are rising twice the global average due to wind and heat, a top scientist has said. Sea levels in the north Indian Ocean was rising about 0.3mm a year for decades, and from 2004 gained about 6mm annually, M Ravichandran, director of National Centre for Antarctic and Ocean Research said.
“The sea levels in the Indian Ocean are almost double of the global mean in the present decade,” he said.
Ravichandran said the rise in sea levels was due to wind flows, which led to surge in warm water on the surface of the Indian Ocean. “This cycle is mainly because of the wind, which drives the sea level,” he said.
Ravichandran said in other oceans, the rise in sea levels is due to melting of glaciers, while in the Indian Ocean it is due to thermal expansion of water. “Wind and heat both play a role in the sea level rise in the Indian Ocean. It is not so much due to melting of ice caps or global warming,” he said.
The NCAOR director also said heat content in the Indian Ocean was more as it was landlocked on the northern side. “The heat trapped in the equator is circulated to poles, whereas the Indian Ocean is blocked from the northern side due the Indian subcontinent (land mass) and the Himalayas. Thus, the heat remains trapped,” he said.
Ravichandran said whatever heat was accumulated in the tropics would remain stagnant. “In other words, there is no ventilation,” he said. Ravichandran said it has a direct effect on the marine life of the Indian Ocean. The increase in sea levels results in the ocean temperature also remaining warm. This warm water then accumulates on the surface of the sea and thus, affects fish life.
As a natural cyclical process, the bottom nutrient-rich water comes to the surface of the sea. When the nutrients come in contact with sunlight, the phytoplankton and zooplankton (part of oceanic food chains) are formed, which serve as food for fish, bringing them to the surface.
“Since (the otherwise colder) bottom water will not come up when there is warm water, it (the nutrient-rich water) will remain trapped below surface level. Most of the fish stay in the top 100 metres of the surface water thus, making their survival difficult in this scenario,” Ravichandran said