What do you think of this fact?
When it comes to oxygen, most people think of forests. Trees matter, no question. But a big share of the air we breathe comes from somewhere else entirely: the ocean.
Tiny oxygen factories
According to the US agency NOAA, about half of the oxygen on Earth is produced in the ocean. The ones responsible aren’t big plants, but mostly phytoplankton. These are tiny organisms that drift in the water and use sunlight to photosynthesize, just like plants on land.
The website EarthSky even gives a range of 50 to 80 percent. The exact figure is hard to pin down because plankton changes a lot depending on the season, the water and nutrients.
A bacterium with a big impact
According to NOAA, one special star is a tiny bacterium called Prochlorococcus. According to NOAA, it’s the smallest photosynthetic organism on Earth. Still, according to NOAA, it produces up to 20 percent of the oxygen in the entire biosphere.
There’s a catch, though. According to NOAA, marine life itself uses up roughly as much oxygen as is produced there. Fish, animals and bacteria that break down dead plankton need it too.
Bonus fact: When large algal blooms die, their decomposition can use up oxygen faster than it’s replaced, according to NOAA. That creates low-oxygen “dead zones” where most marine life can’t survive.
That shows how closely the ocean and the atmosphere are linked. Whatever happens to plankton, for example because of warmer water, affects the whole planet.
So when you take a deep breath at the beach, you can thank a few billion tiny sea creatures. They work around the clock, and not one of them is bigger than a speck of dust.