Search This Blog

Thursday, July 1, 2021

birth of new Ocean ~ "Southern Ocean" (Antarctic Ocean)

A thing of beauty is a joy for ever ~ and one such is ‘Marina beach’ known for its  pristine beautiful sandy shores.   The sands of marina on the Bay of Bengal  is famed for the  ambience and rich eco system though it  stands a lot polluted now. 

Early morning the famous Marina beach offers intriguing things.   Nearer the Ocean, it is more enticing ! – one can hear the sea, the sound of waves, the  waves jumping and touching the shore and then submitting themselves to the shore but trying to comeback to conquer again ! would be very interesting sight  – One  can see monstrous  ships anchored in the middle of vast Ocean, some fishing boats and Sun coming out as a red ball from the Sea – all great sights to behold.  Bay of Bengal (Vanga Kadal) is an enticer – one gets lost in its beauty watching the waves and ships.  Roughly triangular, the sea borders India on its Southern side and then Srilanka, Bangladesh, Myanmar, Andaman & Nicobar islands.   The sea occupies an area of 2,172,000 square kilometres (839,000 sq mi). A number of large rivers – the Ganges and its tributaries such as the Padma and Hooghly, the Brahmaputra and its tributaries such as the Jamuna and Meghna, other rivers such as the Irawathi, Godavari, Mahanadi, Krishna and Kaveri flow into the Bay of Bengal.

Only recently understood that the description above is wrong !  - Bay of Bengal is a Sea not an Ocean.   Many a times, people use the terms "ocean" and "sea" interchangeably when speaking about the ocean, but there is a difference between the two terms when speaking of geography (the study of the Earth's surface).  Seas are smaller than oceans and are usually located where the land and ocean meet. Typically, seas are partially enclosed by land ! ~ and Bay of Bengal fits this description.

While there is only one global ocean, the vast body of water that covers 71 percent of the Earth is geographically divided into distinct named regions. The boundaries between these regions have evolved over time for a variety of historical, cultural, geographical, and scientific reasons. Historically, there are four named oceans: the Atlantic, Pacific, Indian, and Arctic.   

The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth. Seawater covers approximately 361,000,000 km2 (139,000,000 sq mi) and is customarily divided into several principal oceans and smaller seas.  As the world's ocean is the principal component of Earth's hydrosphere, it is integral to life, forms part of the carbon cycle, and influences climate and weather patterns. The ocean is the habitat of 230,000 known species, but because much of it is unexplored, the number of species in the ocean is much larger, possibly over two million.

Historically, there are four named oceans: the Atlantic, Pacific, Indian, and Arctic. However, most countries - including the United States - now recognize the Southern (Antarctic) as the fifth ocean.  The Southern Ocean is the 'newest' named ocean. It is recognized by the U.S. Board on Geographic Names as the body of water extending from the coast of Antarctica to the line of latitude at 60 degrees South. The boundaries of this ocean were proposed to the International Hydrographic Organization in 2000. However, not all countries agree on the proposed boundaries, so this has yet to be ratified by members of the IHO. The U.S. is a member of the IHO, represented by the NOS Office of Coast Survey.

Since National Geographic began making maps in 1915, it has recognized four oceans: the Atlantic, Pacific, Indian, and Arctic Oceans. Starting on June 8, 2021 World Oceans Day, it will recognize the Southern Ocean as the world’s fifth ocean. “The Southern Ocean has long been recognized by scientists, but because there was never agreement internationally, we never officially recognized it,” says National Geographic Society Geographer Alex Tait.  The Gerlache Strait lies off the west coast of the Antarctic Peninsula, in the large band of ocean around Antarctica that has been reclassified as the Southern Ocean by National Geographic cartographers. The strait would once have been considered part of the Pacific.

On World Oceans Day, Nat Geo cartographers say the swift current circling Antarctica keeps the waters there distinct and worthy of their own name: the Southern Ocean.  Those familiar with the Southern Ocean, the body of water encircling Antarctica, know it’s unlike any other. “Anyone who has been there will struggle to explain what's so mesmerizing about it, but they'll all agree that the glaciers are bluer, the air colder, the mountains more intimidating, and the landscapes more captivating than anywhere else you can go,” says Seth Sykora-Bodie, a marine scientist at the National Oceanic and Atmospheric Administration (NOAA) and a National Geographic Explorer.

Geographers debated whether the waters around Antarctica had enough unique characteristics to deserve their own name, or whether they were simply cold, southern extensions of the Pacific, Atlantic, and Indian Oceans.  “It’s sort of geographic nerdiness in some ways,” Tait says. He and the National Geographic Society’s map policy committee had been considering the change for years, watching as scientists and the press increasingly used the term Southern Ocean. The change, he adds, aligns with the Society’s initiative to conserve the world’s oceans, focusing public awareness onto a region in particular need of a conservation spotlight. Marine biologist and National Geographic Explorer at Large Sylvia Earle praised the cartographic update.  

While the other oceans are defined by the continents that fence them in, the Southern Ocean is defined by a current.  Scientists estimate that the Antarctic Circumpolar Current (ACC)  was established roughly 34 million years ago, when Antarctica separated from South America. That allowed for the unimpeded flow of water around the bottom of the Earth.  The ACC flows from west to east around Antarctica, in a broad fluctuating band roughly centered around a latitude of 60 degrees south—the line that is now defined as the northern boundary of the Southern Ocean. Inside the ACC, the waters are colder and slightly less salty than ocean waters to the north.  Extending from the surface to the ocean floor, the ACC transports more water than any other ocean current. It pulls in waters from the Atlantic, Pacific, and Indian Oceans, helping drive a global circulation system known as the conveyor belt, which transports heat around the planet. Cold, dense water that sinks to the ocean floor off Antarctica also helps store carbon in the deep ocean. In both those ways, the Southern Ocean has a crucial impact on Earth’s climate.

Scientists are currently studying how human-driven climate change is altering the Southern Ocean. Ocean water moving through the ACC is warming, scientists have learned, but it’s unclear how much this is impacting Antarctica. Some of the most rapid melting of the continents ice sheets and shelves have been where the ACC is closest to land.  For now, by fencing in the frigid southern waters, the ACC helps keep Antarctica cold and the Southern Ocean ecologically distinct. Thousands of species live there and nowhere else. The Southern Ocean “encompasses unique and fragile marine ecosystems that are home to wonderful marine life such as whales, penguins, and seals,” notes National Geographic Explorer in Residence Enric Sala. What’s more, the Southern Ocean has ecological effects elsewhere as well. Humpback whales, for example, feed on krill off Antarctica and migrate far north to winter in very different ecosystems off South and Central America. Some seabirds migrate in and out too.

By drawing attention to the Southern Ocean, the National Geographic Society hopes to promote its conservation. Sounds very interesting !

With regards – S. Sampathkumar
14th June 2021.