At least half the oxygen you breathe comes from the ocean
Forget the rainforests — the planet's biggest oxygen factory is microscopic and floats in the sea.
It’s easy to credit forests for the air we breathe, but the ocean is the bigger lung. NOAA estimates that at least half of Earth’s oxygen is produced in the sea, and Woods Hole puts it at more than half.
The work is done by phytoplankton — drifting algae and photosynthetic bacteria too small to see. A single genus, Prochlorococcus, may be the most abundant photosynthesiser on Earth and is thought to generate up to 20 percent of the oxygen in the entire biosphere — more than all tropical rainforests combined.
There’s a catch: most of that oxygen is consumed again by marine life and decomposition. Only a fraction escapes to the atmosphere — but over billions of years, that fraction built the breathable air we depend on.
Sources & references
2 referencesWell-established. Corroborated by 2 independent sources.
