The oceans produce the majority of the oxygen on Earth through the photosynthesis of phytoplankton and marine algae, which release oxygen when they absorb carbon dioxide.
Phytoplankton are microscopic organisms that float near the surface of the oceans and perform photosynthesis, somewhat like terrestrial plants. They alone generate about half of the oxygen we breathe on Earth, far more than all the forests in the world combined. These tiny organisms capture carbon dioxide and release oxygen thanks to the sun. Without them, the composition of the air would change radically, and we would have much more difficulty breathing. And phytoplankton doesn't just provide oxygen: it is also the foundation of the oceanic food chain, feeding a host of larger organisms. In short, these microscopic little guys literally do a huge part of the work to sustain life on Earth.
In the oceans, the central process that produces oxygen on a large scale is photosynthesis. Specifically, microscopic organisms called phytoplankton capture sunlight using a well-known green pigment, chlorophyll. They use this light energy to naturally transform water and carbon dioxide (CO₂) into sugars that fuel their growth. During this transformation, they release a rather useful byproduct for us: oxygen (O₂). This phenomenon, reminiscent of land plants, occurs on a very large scale, primarily at the surface, where light is abundant, gradually enriching the Earth's atmosphere with oxygen. This small mechanism, operated by a massive amount of phytoplankton, largely explains why the majority of the oxygen available on Earth actually comes from the oceans.
Marine algae actively contribute to the survival of our planet by producing a large portion of the oxygen you breathe. Through photosynthesis, these organisms absorb carbon dioxide present in water and then release oxygen in return. Some giant algae, like kelps, form true underwater forests capable of releasing enormous amounts of oxygen daily. Even microscopic algae, invisible to the naked eye, proliferate beneath the waves and together represent a major contribution to the renewal of the air in the atmosphere. Ultimately, these marine plants do much more than color our beaches green: they are one of the essential lungs of our planet.
Oceans absorb a large part of the carbon dioxide (CO2) produced by human activities, acting like a giant sponge. Specifically, when this CO2 dissolves in seawater, it mainly turns into carbonic acid and bicarbonate ions. Some of it even ends up being deposited in a solid form in marine sediments. Through this process, a huge amount of carbon is captured and stored in the water rather than remaining in the atmosphere. In other words, oceans serve the very practical role of a natural reservoir, reducing the greenhouse effect while indirectly helping to maintain an oxygen level favorable to life on Earth. However, this system has its limits: the more carbon the oceans absorb, the more acidic they become, which poses problems for a whole range of marine organisms.
The oceans and the atmosphere are constantly exchanging gases, including carbon dioxide (CO2) and oxygen. At the surface, the ocean absorbs some of the atmospheric CO2, which limits its concentration in the air and reduces the greenhouse effect. Conversely, the ocean releases oxygen produced by phytoplankton and marine algae. Wind and ocean currents greatly facilitate these daily gas exchanges. Essentially, the ocean and the atmosphere form a dynamic team that jointly regulates our climate and the quality of the air we breathe every day.
Marine phytoplankton forms the basis of many oceanic food chains, directly or indirectly supporting nearly 95% of marine life forms.
Unlike terrestrial forests that primarily produce oxygen during the day, certain species of marine phytoplankton can perform photosynthesis at significant depths and even in very low light!
Some marine algae, such as diatoms, not only produce a significant portion of the Earth's oxygen, but they also play a fundamental role in regulating the global climate by capturing enormous amounts of CO₂.
A single drop of seawater can contain up to a million microscopic phytoplankton organisms capable of photosynthesis, thereby playing a crucial role in global oxygen production.
Yes, the productivity of oceanic phytoplankton varies with the seasons. For example, in spring, due to the increase in light and nutrients, certain oceanic regions experience a significant phytoplankton bloom known as a 'spring bloom,' temporarily boosting oxygen production.
Yes, oceans play a fundamental role in regulating the planetary climate due to their capacity to absorb carbon dioxide and exchange heat and moisture with the atmosphere, thereby influencing global weather conditions.
The disappearance of phytoplankton would have catastrophic effects on the planet, causing a significant decline in global oxygen production and disrupting marine ecosystems, impacting the survival of numerous terrestrial and aquatic species.
Yes, contrary to popular belief, the oceans, through phytoplankton and marine algae, produce more oxygen than all the terrestrial forests combined.
Phytoplankton, made up of microalgae suspended in the oceans, captures sunlight to convert carbon dioxide (CO2) into oxygen through the natural process of photosynthesis, which is responsible for a significant portion of the oxygen in the atmosphere.
Approximately 50 to 80% of atmospheric oxygen is produced by the oceans, primarily thanks to phytoplankton and marine algae performing photosynthesis.
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