Why our oceans are vital for us
When you look at the ocean you probably don´t realize it, but our oceans contribute between 50 to 85 percent of the oxygen on earth. Photosynthesizers like phytoplankton, tiny ocean plants - including bacteria and algae - that live near the water´s surface, and seaweed use sunlight and carbon dioxide to make food (photosynthesis). A byproduct of photosynthesis is oxygen. When phytoplankton die, they sink to the deep ocean and the carbon dioxide stored in them goes with them. This process is called the biological pump.
Scientists are trying to measure how much oxygen they provide, but it is a difficult thing to do. In the lab, scientists can determine how much oxygen is produced by a single phytoplankton cell. But it is very hard to know how much phytoplankton live in the oceans. It blooms in spring and when there is less sunlight and nutrients available there is also less phytoplankton.
Plankton, from the Greek root Planktos (wanderer/drifter), float throughout aquatic ecosystems since they are unable to swim against currents, tides or waves. Marine photosynthesizers have been around for a long time. The oldest known fossil is from a marine cyanobacterium, a tiny-blue green photosynthesizer, and is 3.5 billion years old. These bacteria have played a critical role in the evolution of life on earth. By generating oxygen during the Archaean (4 to 2.5 billion years ago) and the Proterozoic Era (2.5 billion to 541 million years ago) they changed the earth´s atmosphere. The appearance of free oxygen led to the Great Oxidation Event 2.45 billion years ago. Before that time the atmosphere was unsuitable for life as we know it today.
But these important tiny creatures are under threat of climate change. As the climate warms, the oceans will too. Phytoplankton thrive better in cooler waters and already gradually warming ocean waters have decreased phytoplankton globally by 40% since 1950. Phytoplankton are like pastures to marine life and while healthy ocean pastures feed all of ocean life they also control and sustain their favored environment by performing ‘plankton cooling’ which they accomplish by creating clouds. Clouds in our planets skies reflect 25% of the suns heat and much dangerous UV radiation back into space. The majority of clouds that moderate the climate on our planet come from ocean plankton blooms that require shelter from both heat and UV sunburns.
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Picture: NOAA