Question One
Most plants can make organic compounds by combining carbon dioxide from the atmosphere with water in various processes including photosynthesis. This means that increase in vegetation increases the utilization of atmospheric carbon dioxide hence causing a general decrease in atmospheric carbon levels. Likewise, when the amount of vegetation is reduced, the utilization of atmospheric carbon is reduced, hence, leading to a buildup of carbon in the atmosphere (Wigley & Schimel, 2000). In short, the association between vegetation and atmospheric carbon is a negative one. As such, reducing the amount of vegetation by half in a period of one hundred years should increase the amount at almost the same rate. However, the amount of atmospheric carbon will increase at the same rate with which vegetation will be reducing. In short, the negative association will not be a linear association. This is because vegetation is not the only utilizing of atmospheric carbon. Moreover, the possibility that an increased rate of deforestation will mean there will be an increased use of wood as fuel or there will be an increase in the rate at which wood will be decomposing – both processes release carbon into the atmosphere. Finally, the likelihood of the climatic impacts of deforestation imposing changes of the carbon cycle in case of deforestation is likely hence an unpredictable rate of increase in atmospheric carbon.
Question Two
As is evidenced by the simulation, although the level of soil carbon is generally higher than that of ocean carbon, it is predicted that ocean carbon is likely to increase at a faster rate than soil carbon. In short, the ocean carbon sink is increasing faster than the soil carbon sink. There are many things that can explain this. First, simple chemistry allows for more carbon dioxide, which is soluble in water, to dissolve in sea water as it builds up in the atmosphere. Secondly, increased use of fire is likely to consistently curtail the increase in soil carbon levels by releasing it to the atmosphere. Moreover, increased use of fossil fuels and the consequent weather changes of global warming will favor wastage of carbon from the soil into the ocean mainly by way of erosion (Wigley & Schimel, 2000). Finally, increased atmospheric carbon dioxide in future is likely to promote the health of ocean plants hence causes further retention of carbon in the sea. Although the carbon levels in soil have also been predicted to rise, the rise in oceanic carbon will be more rapid.
Question Three
The most important single source of soil carbon is plant residues, which include leaves, shoots, and stems. The type of plant and the amount of residue are the key determinants of the amount of carbon injected into the soil by the given residues. The second important source of increasing soil carbon is animal wastes and residues. A mixture of plant residues and animal waste, which is mostly referred to as manure, is often used by farmers to increase the carbon levels in the soils they cultivate. Even though plant animal wastes contribute considerably to increase in soil carbon levels, whole animals like carcasses also add to soil carbon. Increases in soil carbon are, however, made much more complex due to subtle losses like those which are due to putrefaction, erosion, or burning of the soil.
Question Four
An increase in fossil fuel consumption causes a direct increase in atmospheric carbon dioxide. Thus, there will be an increased availability of Carbon dioxide for use by terrestrial plants in the process of photosynthesis. The process of photosynthesis converts carbon into organic compounds that are utilized and stored in the plants, causing an increase in the amount of carbon that is in the terrestrial plants. Therefore, there is a positive association between utilization of fossil fuels and the amount of carbon in terrestrial plants (Wigley & Schimel, 2000). The relationship is, however, not linear due to the effect of other consumers of carbon dioxide for example sea water. More importantly, there is likely to be a limit in this relationship: Too much increase in consumption of fossil fuels can lead to the build-up of atmospheric carbon dioxide to levels that are dangerous to the ecosystem – in this case, the consequent death and putrefaction of plants due to the effects of global warming will cause a direct decrease in the amount of carbon available in terrestrial plants.
Question Five
An increase in the smokestack means that there will be an increase in the amount of atmospheric carbon in the form of carbon dioxide. This carbon continually dissolves in sea water, especially the surface water, causing an increase in the total sea carbon. In essence, there exists a positive association between the smokestack concentration and the amount of carbon in surface sea water. In 50 years, this consistent increase in sea carbon levels will enhance the life of autophytic plants. Most other forms of sea flora depend on these autophytes, hence, improvement in sea flora (Wigley & Schimel, 2000). However, the scenario could be different for the fauna. Inasmuch as the availability of food will be increased, the increased amount of carbon dioxide and the thus the limited availability of oxygen could cause the death of the animals, causing a decrease in sea fauna. Animals tend to use more oxygen in the process of respiration; they do not release oxygen in their biological processes and do not need carbon dioxide – an increase in the concentration of carbon dioxide in their environment, thus, makes the environment hostile and unsuitable.
Question Six
The atmosphere, as a sink, is likely to be affected more rapidly and strongly by an increase in carbon dioxide release through increased fossil fuel consumption when compared to other sinks like terrestrial plants, the ocean, and the soil. The atmosphere is like the reservoir sink, any carbon that is released by fossil fuel utilization is first released from the atmosphere and then distributed to the other sinks – this explains the fast rate at which atmospheric carbon levels increase. The higher severity of the increase in atmospheric carbon levels when compared to that of other sinks can be explained by the fact that the increase in atmospheric carbon is directly due to the increased utilization of fossil fuels while the increase in other sinks in dependent on many other factors (Wigley & Schimel, 2000). Oceanic carbon, for instance, is likely to increase at a slower rate because of global warming which comes as a result of increased atmospheric carbon-dioxide. The same can be said about the carbon in terrestrial plants. The carbon in soil increases slowly because of burning practices that deplete soil carbon – increased utilization of fossil fuels is likely to be associated with increased burning.
Question Seven
An increase in atmospheric carbon levels causes an increase in the total amount of carbon in the deep sea sink. Though the association, in this case, is positive, it is usually not linear because of the effect of confounding factors like the increased temperature that results from the increase in atmospheric carbon levels. Moreover, the whole process by which atmospheric carbon dioxide accesses the cooler deep sea waters is in itself a confounding factor. An increase in atmospheric carbon dioxide saturates the surface ocean waters as carbon dioxide is naturally soluble in water. Carbon dioxide reacts with the salty sea water to form weak carbonic acid hence a decrease in the pH of sea water. The carbonic acid dissociates into hydrogen ions and bicarbonate ions – carbon in the form of bicarbonate ions can rarely leave sea water (Wigley & Schimel, 2000). The seepage of the carbon into deep sea waters is dependent on two processes – the utilization of carbon by deep sea flora and the mixture of deep sea and surface waters because of the winds. Therefore, it is hard to predict the exact rise in deep sea carbon with every increment in atmospheric carbon levels.
Question Eight
A decrease in utilization of fossil fuels greatly reduces the emission of carbon dioxide into the atmosphere. The processes that tend to remove carbon dioxide from the atmosphere do not cease hence causing a reduction in the amount of atmospheric carbon. In other words, the amount of atmospheric carbon dioxide is directly proportional to the amount of fossil fuels being used (Wigley & Schimel, 2000). Failure to emit carbon by stopping the utilization of fossil fuels is likely to cause a negative carbon balance – the amount of atmospheric carbon will keep decreasing. The amount of carbon in terrestrial plants, as a sink, also reduces. This is because the reduced availability of atmospheric carbon dioxide for the plants reduces the rate and productivity of photosynthesis hence causing a negative balance in the plants – the plants die more than they grow (Wigley & Schimel, 2000). Dead plants donate their carbon either to the soil or the atmosphere. This explains why a negative balance in the life of plants is likely to cause a reduction in the total carbon that is contained in plants.
Question Nine
As seen from the simulation, decreased utilization of fossil fuels decreases the amount of carbon in the atmosphere and in terrestrial plants. The amount of carbon is the soil remains largely unchanged – it shows a very slow reduction. The amount of carbon in surface waters is static – it only shows a little gross increase. The sink that shows the greatest increase is the deep sea. This is where the carbon that is depleted from the atmosphere is stored. This can be explained by the fact that sea water, which is a solvent for carbon dioxide, keeps sucking up atmospheric carbon. The carbon is the saturated surface waters eventually gets to the deep sea waters due to the effect of the wind which causes a mixture of deep sea waters and the surface waters (Wigley & Schimel, 2000). In the deeper and cooler sea waters, carbon exists in the form of bicarbonate – this form of carbon is not easily lost from the sea, hence, the continued increase in the total carbon levels in the deep sea at the expense of atmospheric carbon.
Reference
Wigley, T. M. L. & Schimel, D. S.. (2000). The carbon cycle. Cambridge: Cambridge University Press.
