Phytoplankton are microscopic organisms in the ocean that use energy of the sun and carbon dioxide (CO2) to produce marine organic matter, just like plants on land. They constitute just 1% of the photosynthetic Earth biomass, but produce half of the World’s oxygen, which the same amount of oxygen as all the plants on land.
Some studies show that without phytoplankton CO2 concentrations would have increased by 200 ppm, which would have been a disaster for humans. Today CO2 concentration is 417 ppm and according to latest projections, at the level 500 ppm extreme weather and sea level rise would endanger global food supplies and other economy sectors. This shows that tiny phytoplankton are doing a very important job for the whole planet by decreasing the levels of CO2.