Water covers more than 70% of our planet, and the ocean contains 96.5% of this water. It turns out that experts cannot agree on how many oceans there really are on Earth.
According to the National Oceanic and Atmospheric Administration (NOAA), there is technically only one global ocean because all marine environments are interconnected in some way.
However, there are also four geographically defined ocean basins: the Atlantic Ocean, the Pacific Ocean, the Indian Ocean, and the Arctic Ocean.
And in 2021, the National Geographic Society added another layer of complexity to the debate by announcing the existence of a Fifth Ocean in the frigid waters surrounding Antarctica, the Southern Ocean.
Does our planet have one, four or five oceans?
The oceans are the largest bodies of water in the world, although there is no consensus on their official definition. The International Hydrographic Organization, which consists of 98 member states and is responsible for determining the boundaries of the ocean, has not yet recognized the Southern Ocean because it has not received full consent from all its members.
While other oceans are defined by the continents they border, the Southern Ocean is distinguished by its current, which flows from west to east and is known as the Antarctic Current (ACT). This unique current, which probably formed 34 million years ago, circulates in the waters surrounding Antarctica up to about 60 degrees south latitude, with the exception of the Drake Passage and the Scotia Sea. The ACC draws water from the Atlantic, Pacific and Indian oceans to transfer heat around the world.
Winds in the area contribute to a phenomenon called bottoming, when cold, nutrient-rich water rises to the surface of the sea. Once on the surface, the water absorbs carbon from the atmosphere before sinking back down. And a 2021 NASA study found that this makes the Southern Ocean one of the largest sinks of carbon on Earth.
“It’s kind of a great link connecting other oceans,” said Frank Nitzsche, a marine researcher at Columbia University’s Lamont-Doherty Earth Observatory who has studied the Southern Ocean for decades. When the National Geographic Society officially recognized the Southern Ocean in 2021, “I really don’t understood that it was not really official.
And if the scientists who study them already recognize different oceans, what difference does it make whether the ocean has an official name or not? It can help people understand the marine problems in their region, said Renles Perez, an ocean researcher at NOAA.
“We really like to think of things as a global ocean, but it’s especially helpful to think about different regions and talk about more regional issues. I think it’s hard for people to understand some of the major ocean issues on a global scale,” she said.
Source: Living Science