Describe the effects of human activities in influencing natural ecosystem cycles with special reference to carbon cycle.

The carbon cycle is a natural process and left undisturbed by natural or human processes, it maintains a stable concentration in the atmosphere (air), biosphere (organic carbon in soil), hydrosphere (water), and lithosphere (inorganic carbon in soil). As the stores are linked, a change in any of the carbon reservoirs causes changes in the others. Actions by humans resulted in the removal of carbon from carbon sinks, directly adding it to the atmosphere.

The main impacts of the carbon cycle are the burning of fossil fuels and deforestation. Under natural conditions, the discharge of carbon from fossil fuels occurs slowly, as they are sub-ducted (the sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate) into the mantle (In geology, the mantle is the part of the earth that lies between the layer of crust and the core), and CO2 is released through burst of volcano. However, humans depend on fossil fuels and extract it in great quantities. The burning of coal, oil, natural gas, and other fossil fuels for industrial activity and power generation are the major need of human in carbon. For example, removal of the carbon from fossil fuels releases it as CO2 into the atmosphere.

Large volumes of carbon are stored in living plants. The removal of the forest can affect the carbon cycle in two ways. The removal of plants leads to elimination of plants these results in the capturing of carbon to the atmosphere through photosynthesis. Furthermore, the forests are replaced by crops or plain land; it leads to a decrease in the carbon store, as smaller plants store less carbon than big trees. Deforestation also allows the soil to be eroded, and carbon stored in the soil is carried into rivers. Because of the nature of the carbon cycle, the impacts humans cause, lead to several multiplied effects and response. Increasing atmospheric CO2 and CH4 causes an increase in global air temperatures which in turn increases decay in soil, thereby releasing more CO2 to the atmosphere. Increases in global temperature also affect ocean temperatures, changes the hydrosphere ecosystems and having the potential to upset the hydrosphere carbon cycle, limiting the ocean’s ability to absorb and store carbon.