[00:09] Floating near the sunlit surface of Earth's oceans, billions of tiny organisms called phytoplankton are the base of the food pyramid for all life. They also shape global climate.

[00:20] From space, different colors of ocean water reveal different concentrations of phytoplankton.

[00:26] Phytoplankton play a critical role in balancing the amount of carbon dioxide in the atmosphere.

[00:31] During photosynthesis, phytoplankton capture water from their surroundings, carbon dioxide from the air, and energy from the sun to build plant material, the primary food source for aquatic life.

[00:42] While most phytoplankton are eaten by other tiny organisms and fish, some of them sink, and are eventually buried under sediment for centuries.

[00:51] In this way, phytoplankton extract nearly half of the atmosphere's carbon dioxide that otherwise would trap the sun's energy and warm the planet.

[00:59] Phytoplankton also generate as a by-product more than half of the oxygen we breathe.

[01:05] For the first 2-billion years, Earth's atmosphere lacked oxygen. Phytoplankton patiently re-engineered the atmosphere to where it now has 21-percent oxygen, a supply upon which we are critically dependent.

[01:19] Earth is a complex system, a web of interdependencies. Some of the tiniest things in the sea create conditions suitable for some of the largest things on land.