The Concept Of Carbon Neutrality

The Concept Of Carbon Neutrality

Carbon neutrality can be understood from two aspects: carbon emissions (carbon sources) and carbon fixation (carbon sinks). Carbon emissions can be generated by both human and natural processes. Human processes mainly come from two major sources: one is the combustion of fossil fuels to form carbon dioxide (CO2) and release it into the atmosphere; the other is land use change (the most typical example is the carbon in the soil being oxidized into carbon dioxide and released into the atmosphere after deforestation); there are also many processes in nature that can release carbon dioxide into the atmosphere, such as volcanic eruptions and underground spontaneous combustion of coal.

Carbon fixation can be divided into two categories: natural fixation and artificial fixation, with natural fixation being the main one. The most important natural carbon fixation process comes from terrestrial ecosystems. Among the many types of terrestrial ecosystems, forest ecosystems account for the majority. The so-called artificial fixation of carbon dioxide can be done by collecting carbon dioxide and converting it into other chemicals through biological or chemical processes, or by  sealing carbon dioxide deep underground or in the ocean.

In the past few decades, about 54% of the carbon dioxide emitted by humans has been absorbed and fixed by natural processes, and the remaining 46% remains in the  atmosphere. Of the 54% absorbed naturally, 23% is completed by the ocean and 31% by terrestrial ecosystems. For example, in recent years, the global annual carbon emissions are about 40 billion tons of carbon dioxide, of which 86% comes from fossil fuel combustion and 14% is caused by land use changes. 18.4 billion tons (46%) of the 40 billion tons of carbon dioxide are added to the atmosphere, resulting in an increase in atmospheric carbon dioxide concentration of about 2ppmv.

The carbon neutrality is the concentration of atmospheric carbon dioxide from increasing. We can imagine that even if our economic and social operating system reaches the stage where it is capable of achieving carbon neutrality, there will definitely be a part of "carbon dioxide that has to be emitted". On the one hand, there will be about 54% of natural carbon fixation processes for them, and the rest will have to be eliminated through ecosystem carbon fixation, artificial conversion of carbon dioxide into chemical products or storage underground. Only when the amount of emissions is equal to the amount of fixation can carbon neutrality be achieved. It can be seen from this that carbon neutrality and zero carbon emissions are two different concepts, and it is marked by the fact that the concentration of carbon dioxide in the atmosphere no longer increases.