The 7 seas, our carbon storage locker.

Rain forests are known as the lungs of the earth, absorbing carbon dioxide and releasing oxygen. Like the forest on the land, the ocean and its inhabitants are part of the carbon cycle, storing carbon and producing oxygen.

Carbon is the basic building block of all life – it is present in all living things on Earth and is stored in plants, land and in the ocean. Carbon passes through the Earth and all its inhabitants in a process called the Carbon Cycle. Through this cycle, carbon is reused in a continuous cycle forever.

Photo by Rodion Kutsaev on Unsplash

Carbon is found in our atmosphere as carbon dioxide, and carbon dioxide is a greenhouse gas that traps heat in the Earth. While carbon dioxide is produced naturally, human activities such as the burning of fossil fuels for energy is releasing carbon dioxide into the environment. Why does the burning of fuels release carbon dioxide? When animals die, the carbon in them is locked away and buried under the earth. Over time with heat and pressure, their remains may turn into sources of fuel, such as natural gas, crude oil and coal. When these fuels are used for energy, the carbon that was once stored in them is released into the environment, where it becomes carbon dioxide. Current human activities are releasing carbon at such high levels and in such short periods that it is becoming too much for the Earth to handle. This has led to global warming.

Luckily for us, carbon sinks, which are plants, land and ocean, absorb carbon dioxide through the carbon cycle and store them away for periods of time, be it a day or a millennium. Thanks to these carbon sinks, about 50% of carbon dioxide produced are removed from the atmosphere, effectively slowing down the warming of the planet.

Photo by Wiltven Lim

The ocean is the second largest carbon sink on earth, and research has found that the ocean absorbed 31% of carbon dioxide produced by humans between 1994 and 2007. The ocean absorbs carbon dioxide through 2 ways. The first is the natural exchange of gas between the ocean surface and the atmosphere, which accounts for 90% of the CO2 absorbed. Diffusion occurs when the CO2 in the ocean surface is less concentrated than the CO2 in the atmosphere, diffusion will occur, and CO2 will enter the ocean. The movement of the ocean surface encourages gas exchange, and it is proven that colder waters can take up more CO2, so the amount of CO2 in the water differs by regions.

The second way CO2 is absorbed is through the organisms that live in the ocean, mainly phytoplankton. Phytoplankton are a mix of many species of microorganisms, and they live in the surface waters. Using sunlight for photosynthesis, these phytoplankton absorb carbon dioxide and release oxygen into the water. When they die, these phytoplankton sink to the bottom of the ocean, locking the carbon inside them there. Through this process, they account for 10% of the carbon dioxide taken in by the ocean.

Photo by Shane Stagner on Unsplash