About Half of Earth's Oxygen Comes From the Ocean

Forests usually get the credit for the oxygen we breathe, but the sea does a comparable share of the work. NOAA’s National Ocean Service states that scientists estimate roughly half of the oxygen production on Earth comes from the ocean. The majority of it is produced by oceanic plankton, which NOAA describes as drifting plants, algae and some bacteria that can photosynthesize. One of them stands out. Prochlorococcus is the smallest photosynthetic organism on Earth, yet NOAA says this bacteria produces up to 20 percent of the oxygen in the entire biosphere, a higher percentage than all of the tropical rainforests on land combined. There is a catch. NOAA notes that about the same amount of oxygen is consumed by marine life.