The ocean produces roughly half of Earth’s oxygen — not the rainforest, which uses up most of what it makes — through photosynthesis by phytoplankton, microscopic marine organisms so abundant that a s

About half of the oxygen on Earth comes from the ocean. Not from the rainforests, which consume close to as much oxygen as they make, but from phytoplankton, the microscopic algae and bacteria that drift through the sunlit surface of the sea and photosynthesise on a scale that is hard to picture. The figure is […] About half of the oxygen on Earth comes from the ocean. Not from the rainforests, which consume close to as much oxygen as they make, but from phytoplankton, the microscopic algae and bacteria that drift through the sunlit surface of the sea and phot... [4442 chars]