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“Carbon balance” is defined as the balance of carbon flows within a specific “carbon cycle” or at the level of the “global carbon cycle.”
The carbon cycle involves three “districts” of the Earth: the hydrosphere, the biosphere, and the atmosphere. These districts are called “carbon sink” and are linked together in what is the natural cycle. A fourth carbon sink “district” is that of the geosphere, in which carbon settles in tens of millions of years and becomes fossil fuel or fossil carbon (Ferrara and Ferrugia 2007). However, the geosphere has no natural connection with the remaining three districts, and the carbon accumulated in it does not come out naturally. The human factor has created an artificial connection “tube” between the geosphere district and the atmosphere, thus connecting the fourth district to the other three, leading to an imbalance between the flows: the carbon released by the geosphere does not return there (at least not before millions of years) and affects the balance of the natural cycle.
The carbon balance, therefore, is used to calculate excesses or defects of these flows and will be important in the near future to try to build solutions to reach new equilibrium phases in the global carbon cycle or a specific cycle. Overcoming the ongoing climate changes also strongly depends on this balance.
The Balance of the Carbon Cycle
The carbon cycle is closely linked to the climate and its transformations and is made up of physical, chemical, and biological phases. This cycle foresees that the plants on Earth through the chlorophyll photosynthesis absorb carbon dioxide. The biosphere through the respiration of plants and animals (consumption of oxygen “O2” through cellular respiration and production of carbon dioxide “CO2”), through their decomposition and natural fires, releases carbon into the atmosphere.
Similarly, in the hydrosphere, a close relationship is created between the amount of carbon dioxide present in the air and that dissolved in the water (Post et al. 1990). This presence is due to the pressure created on the surface of the water. In fact, if the exchange coefficient (speed of the molecule to move) of the gas changes, the surface of the water, in turn, releases CO2 into the atmosphere. Just as in the biosphere, living organisms in water also absorb CO2, the most important phytoplankton of all.
The percentage of CO2 in the atmosphere, calculated in parts per million, has grown at a dizzying rate in the last century. Thanks to the coring carried out by scientists in Antarctica, it is possible to know that at the beginning of the 1800s, there were 280 ppm of CO2 (pre-industrial age), while today the instruments record the data of 411 ppm, recorded in December 2019. The explanation of this increase is the human activity which in the industrialization and growth phase developed a strong dependence on fossil fuels which, until then, were kept inside the subsoil. These fuels have put into circulation “ancient” stable carbon, without its radioactive part “carbon-14 (14C),” creating an important imbalance in the carbon cycle. It was the Austrian Hans Suess who studied the variation between the atmospheric concentrations of carbon isotopes (13C and 14C) with the dilution of large quantities of CO2 from fossil fuels and then discovered that it runs out in 13CO2 without containing the 14CO2 radiocarbon that is reused in chlorophyll photosynthesis from plants (Suess effect).
The carbon balance within its natural cycle was previously constant over time. If an excess of carbon had occurred within one district, a defect would have occurred in another. This balanced state of balance, however, changed with the external insertion of carbon from the geosphere, extracted by the human being to conduct its activities.
Until the 1970s, part of the excess carbon was reintroduced into the carbon cycle, thanks to the absorption of the biosphere and hydrosphere. However, these absorptions, which still occur today, do not appear, from the balance sheets, to be sufficient for the current rate of extraction and human use of fossil fuels. In the 1970s, the maximum possible absorption levels at the natural level were reached, calculated at around 3000 megatonnes of carbon, and since then it is possible to observe a strong acceleration of the concentration of carbon in the atmosphere (analyzed in CO2).
In 1827 the French mathematician Jean-Baptiste Fourier for the first time used the term “greenhouse effect” to illustrate how even minimal changes in the atmosphere could alter the climate of the planet. In truth, the greenhouse effect is a natural phenomenon, thanks to which an average temperature on the planet of about 15 °C is possible. In the absence of a greenhouse effect, life on Earth would not be possible (the average temperature on the planet in the absence of a greenhouse effect is estimated to be around −18 °C on average) (Pasini et al. 2006).
The gases that allow the greenhouse effect (therefore called “greenhouse gases”) reabsorb part of the energy re-emitted from the soil, and in the atmosphere, there is a greater amount of energy than the incident solar energy. Because of this and because of the energy released by the same gases, previously accumulated, the temperatures rise strongly. These gases are methane (CH4), nitrous oxide (N2O), ozone (O3), chlorofluorocarbons (CFC), and carbon dioxide (CO2).
The balance of climate-changing gases and CO2 emissions are the subject of great attention by the scientific world because the future of the planet will depend on how much the human being will be able to stabilize its activities by keeping the concentrations of CO2 equivalent in the atmosphere at a sustainable level.
The excess of carbon dioxide in the atmosphere, and consequently in the other three land districts, has increased global temperatures, thus creating a global climate change. Scientists around the world agree that it is the man with his activities who is the primary cause of this excess and that a solution is needed as soon as possible.
The future of the planet and mankind will depend on how much emissions from human activities affect climate events and the increase in global temperatures.
In this future, the analysis of the carbon balance and its cycle will be fundamental to try to understand the optimal direction to take for a readjustment of the economy and human life on earth.
The carbon balance and its cycle must always tend in a balanced and balanced state. The human being must predict awareness that planet Earth is not able to sustain for a long time the development activities without limit and the exploitation of reckless natural resources.
Scholars from all over the world question themselves every day trying to find alternative answers to the economic theories that today are prevailing and globally recognized as valid for the well-being of human civilization.
Tending toward a “carbon-free” development that allows the balance between emissions and absorptions to be brought to zero is the objective to be put in place in the political, economic, and social forums. A new way of thinking about human life, which has less impact on the carbon balance, will require an increasingly greener economy.
Reforestation is an important step that many countries around the world have decided to take to create green lungs capable of supporting current emissions even more. On the contrary, large farms, overfishing, and intensive cultivation are still a major global problem to which the governments of the main industrialized and developing states are not giving due weight (Brown 2009).
The transport sector, especially the automotive sector, being one of the sectors with the most important emissions, has taken on the concept of sustainable mobility and sharing economy in recent decades, with the inclusion of hybrid and electric cars in the global market and with important international brands that have focused on “carsharing”
The design of increasingly energy-efficient houses and buildings will also reduce emissions and waste of energy in the construction and residential life sector.
New technologies, renewable energy sources to be increasingly replaced by fossil fuels, will have to allow for greater energy efficiency in all sectors, from industrial to corporate, from the public to private, only in this way will it be possible to achieve important results on CO2 emissions balance. Applying the new concepts of circular economy and bioeconomy will be fundamental to start producing bioenergy and biomaterials.
The carbon balance in this will be fundamental to understand to every human action how the natural plant and ocean system will respond, which is what will happen to every change of CO2 and climate. It will be necessary to observe the global biogeochemical-climatic system with extreme attention, communicate the results of these observations to the institutions, and ensure that human, economic, and social choices adapt to the balance necessary to stop climate change.
The stability that the balance of the carbon cycle in nature had in the past has been changed by the activities of the human being. The central pivot of these activities is the development of industrialization based on the exploitation of resources, especially of fossil fuels. This exploitation has increased the concentration of carbon dioxide, both in the biosphere and in the hydrosphere, thus increasing the greenhouse effect and temperatures, causing ongoing climate changes and jeopardizing global climate balances. Knowing the functioning of the carbon cycle, the human being must aim at solving the problem through policies that aim at a new balancing of the cycle, regulating emissions on the basis of absorption capacities, in order to adapt its activities to current changes and, by contrasting them, avert the possible catastrophic consequences for life on Earth.
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