Tiny sea forests breathe life into our world

If every tree on Earth disappeared tomorrow, you would still be able to breathe. Between 50% and 80% of the world's oxygen is produced by the ocean.

The heavy lifting is done by phytoplankton—microscopic organisms like diatoms and bacteria that float near the water's surface. They use photosynthesis just like plants do, consuming sunlight and carbon dioxide to pump out oxygen as a waste product.

One specific type of bacteria, Prochlorococcus, is the most abundant photosynthetic organism on the planet. It is so small that millions can fit in a single drop of water, yet it alone produces 20% of the oxygen in our entire biosphere. That is more than all the tropical rainforests on land combined.

This means that every fifth breath you take is powered by a microbe you can't see with the naked eye.

While we focus on planting trees to save the air, the real oxygen factory is the massive, swirling blue lung of the Earth. Most of this oxygen doesn't even stay in the water; it drifts up into the atmosphere, sustaining life miles inland from the nearest beach.