Understand the Indian Ocean and you’ll understand much about earth

• The Indian Ocean has been getting a lot of attention recently for its rapid warming
• As it happens, the Indian Ocean is critical today to understand the earth’s overall ocean response to increasing greenhouse gases and global warming.

Home to the deadliest storms

• The Indian Ocean is famous for its dramatic monsoon winds and the rain it brings to the Indian subcontinent.
• The warm summer months are characterised by the rapid warming of the Arabian Sea and the Bay of Bengal as well as the southern tropical Indian Ocean.
• The winds begin to turn around from a land-to-ocean direction during winter and to an ocean-to-land direction as summer commences.
• The scorching heat on the subcontinent also comes with the threat of pre-monsoon cyclones.
• The North Indian Ocean doesn’t generate as many cyclones as the Pacific or the Atlantic Oceans, but the numbers and their rapid intensification have been growing ominously.
• The developing countries along the rim of South Asia, East Africa, and West Asia are sitting ducks in their path. Thus, cyclones tend to be the deadliest storms by mortality.
• The warm ocean supports fisheries, big and small, and fish such as anchovies, mackerel, sardines, and tuna. Dolphins are a tourist attraction; some whales have also been sighted in the Arabian Sea.
• Tourists also flock to popular beaches and the corals from Lakshadweep to the Andaman-Nicobar Islands, all the way down to Reunion Island off Madagascar.

A unique configuration

• 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 connected to the Pacific and the Southern Oceans.
  • The Indonesian seas connect it to the Pacific Ocean which transports a substantial amount of heat.
  • 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.
• 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.

The little ocean that could

• The Indian Ocean is a warm bathtub because it is heavily influenced by the Pacific Ocean through an atmospheric bridge as well.
  • The Indian Ocean thus gains heat which must be removed by 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 for corals and fisheries.

A hand in 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.
• The storied history of our neighborhood ocean is thus a worthy thing to understand and study on World Oceans Day.