World Oceans Day : June 8
Indian ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering approx. 20% of the water on Earth's surface.
It is bounded by Asia to the north, Africa to the west and Australia to the east.
To the south it is bounded by the Southern Ocean, or Antarctica, depending on the definition in use.
Along its core, the Indian Ocean has large marginal, or regional seas, such as the Andaman Sea, the Arabian Sea, the Bay of Bengal, and the Laccadive Sea
It is the warmest ocean, with a significant impact on global climate due to its interaction with the atmosphere
The Indian Ocean Region (IOR) is a vital maritime area spanning over 36 littoral and island countries.
The region is strategically important due to its significant trade routes, natural resources, and geopolitical importance.
It is home to some of the world’s busiest sea-lanes, including the Straits of Hormuz and Malacca
The northern boundary of the Indian Ocean is closed off by the Asian landmass, minus tiny connections to the Persian Gulf and the Red Sea.
The southern Indian Ocean is also different from the other oceans because of two oceanic tunnels that connect it to the Pacific and the Southern Oceans.
Through the first tunnel — the Indonesian seas — the Pacific Ocean dumps up to 20 million cubic metres of water every second into the eastern Indian Ocean.
These waters also transport a substantial amount of heat
The Pacific waters, called the Indonesian Throughflow, wander around the Indian Ocean and affect the circulation, temperature, and salinities.
The other tunnel connects the Indian Ocean to the Southern Ocean with two-way traffic.
Colder, saltier and thus heavier waters flow into the Indian Ocean from the Southern Ocean below a depth of about 1 km.
Due to the closed northern boundary, the waters slowly mix upward, and with the waters coming from the Pacific.
The waters in the top 1 km eventually exit to the south.
The mix of heat and water masses in the Indian Ocean confer some mighty abilities to affect the uptake of heat in the world’s oceans.
Role in global climate change
The Indian Ocean is a warm bathtub despite the underwater tunnels because it is heavily influenced by the Pacific Ocean through an atmospheric bridge as well.
The atmospheric circulation, dominated by a massive centre of rainfall over the Maritime Continent, creates mostly sinking air over the Indian Ocean.
The atmosphere also warms the Indian Ocean year after year.
The Indian Ocean thus gains heat that it must get rid of via the waters moving south.
With global warming, the Pacific has been dumping some additional heat in the Indian Ocean.
The cold water coming in from the Southern Ocean is also not as cold as before
The net result: the Indian Ocean is among the fastest warming oceans, with dire consequences for heat waves and extreme rain over the Indian subcontinent.
Marine heat waves are also a major concern now for corals and fisheries.
The warming Indian Ocean is affecting the wind circulation in a way that’s also affecting the amount of heat the Pacific is able to take up.
The Pacific Ocean takes up heat in its cold, eastern tropical region, and this is crucial to determine the rate of global warming.
The Indian Ocean is thus playing a role in how well the Pacific can control global warming
Influence on human evolution
Until about three million years ago, Australia and New Guinea were well south of the equator and the Indian Ocean was directly connected to the Pacific Ocean.
And this Indo-Pacific Ocean was in a warm state known as a ‘permanent El Niño’ — a state that was associated with permanently plentiful rain and lush green forests over East Africa. Today, this part of Africa is arid.
The northward drift of Australia and New Guinea, which is still ongoing, separated the Indian and the Pacific Oceans around three million years ago.
As a result, the eastern Pacific Ocean became cooler and the El Niño went from a permanent state to an episodic one
This transition aridified East Africa, turning its rainforests into grasslands and savannahs.
Researchers have also hypothesised that these changes forced our ancestors, such as chimpanzees and gorillas, to move farther and run faster. In the rainforests, they had an abundance of food and hiding places and didn’t have to
COMMENTS