The Earth has four oceans
The core idea stands, but key numbers or details have changed.
TaughtPacific, Atlantic, Indian, and Arctic. Four oceans.
NowFive. The Southern Ocean around Antarctica was proposed by the International Hydrographic Organization in 2000 and formally recognized by National Geographic on World Oceans Day in 2021.
What actually happened
The Southern Ocean is defined differently from the others. The Atlantic and Pacific are bounded by continents; the Southern Ocean is bounded by a current. The Antarctic Circumpolar Current, which flows unobstructed around the continent and is the largest current on Earth, marks water that is colder and less salty than what lies north of it, and it forms a genuine ecological boundary at roughly 60 degrees south.
The IHO proposed formal recognition in 2000, but its member states never ratified the boundary definition, which is why the change took two decades to filter through. NOAA and the US Board on Geographic Names have used it since the 1990s and 1999 respectively. National Geographic's decision in 2021 mattered because its maps are what school classrooms buy, and it was the moment the fifth ocean arrived in mainstream cartography. If your world map had four labeled oceans, the water around Antarctica is now its own.
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Sources
- National Geographic: There's a new ocean nownationalgeographic.com
- NOAA: How many oceans are there?oceanservice.noaa.gov
Who was taught this
Still standard through 2021, so anyone who finished school between 1950 and 2021 learned the earlier version.