What Is a Carbon Sink?

Peat soil can be an example of a natural carbon sink.

A carbon sink is a reservoir that stores carbon-containing chemical compounds for an unspecified period of time. In the recent past, levels of carbon dioxide in the atmosphere have risen significantly. As a result, the world is experiencing detrimental effects of global warming and climate change, such as rising ocean and sea levels, melting of Artic ice, and extreme weather conditions. The function of the carbon sink is to filter carbon dioxide from the atmosphere through a process known as carbon sequestration. Consequently, carbon sinks reduce the impact of high carbon dioxide levels in the atmosphere, resulting in less harm to humans and the Earth as a whole.

Types of Carbon Sinks

There are two main types of carbon sinks: natural and artificial sinks. Examples of natural carbon sinks are trees/forests, oceans, terrestrial plants, and soil. Trees absorb carbon dioxide from the air during the growing season, removing about 10-20 tonnes of carbon dioxide per hectare every year. Oceans, on the other hand, absorb carbon dioxide from the atmosphere through both biological and physiochemical processes. Terrestrial plants absorb carbon dioxide from the air by a process known as photosynthesis. Although the creation of artificial carbon sinks has been considered and attempted, no significant model currently exists.

Natural Methods of Carbon Sequestration

Carbon sequestration can be improved through sustainable forest management, which includes replacing cut trees and strengthening rules around deforestation. Another method involves adding micrometer-sized iron particles, such as iron sulfate and iron oxide, to certain parts of the ocean in order to stimulate the growth of plankton. More plankton increases the removal of significant portions of carbon dioxide from the air through photosynthesis.

Carbon sequestration can also be increased by adopting organic farming methods such as residue mulching, crop rotation, cover cropping, and no-tillage farming. According to the Food and Agriculture Organization of the United Nations (FAO), organic agriculture reduces carbon dioxide emissions by 48-66%. Finally, another natural way of increasing carbon sequestration is the conversion of grasslands to pastureland, combined with better grazing methods.

Artificial Carbon Sequestration

Some of the artificial carbon sequestration methods include applying the use of amine-based solvents and direct injection of carbon dioxide into deep parts of the ocean. Additionally, gathering and depositing crop residue into alluvial fan areas of the deep ocean basin is also useful.

Geological Carbon Sequestration

In addition to natural and artificial carbon sequestration methods, there is another common geological method used to filter carbon dioxide from the air. The process involves injecting carbon dioxide directly into underground geological formations such as declining oil fields.

Challenges to Improving Carbon Sequestration

Despite the potential options described above, improving the natural sequestration of carbon is challenging. For example, the widespread use of conventional agricultural practices by farmers today makes a large shift to organic farming methods difficult. Secondly, humans have damaged the ecosystem through desertification, which is caused by overgrazing, over-cultivation, and deforestation. Deforestation reduces the number of trees. As a result, more carbon dioxide is retained in the atmosphere. Thirdly, human-induced weather changes have weakened the ability of oceans to act as a carbon dioxide “sponge.”

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