Day 4: Carbon Cycle

Carbon cycles Among Living and Nonliving Things 

A key component of the carbon cycle is carbon dioxide (CO2) gas. It makes up about 0.040% of the volume of the earth's troposphere. Carbon dioxide (along with water vapor in the water cycle) affects the temperature of the atmosphere through the greenhouse effect and thus plays a major role in determining the earth's climate. If the carbon cycle removes too much CO2 from the atmosphere, the atmosphere will cool, and if it generates too much CO2, the atmosphere will get warmer. Thus, even slight changes in this cycle caused by natural or human factors can affect the earth's climate, which helps determine the types of life that can exist in various places. 

Carbon is cycled through the biosphere by a combination of photosynthesis by producers that removes CO2 from the air and water, and aerobic respiration by producers, consumers and decomposers that adds CO2 in the atmosphere. Typically, CO@ remains in the atmsphere for 100 years or more. Some of the CO2 in the atmosphere dissolves in the ocean. In the ocean, decomposers release carbon that is stored as insoluble carbonate minerals and rocks in bottom sediment for long periods. marine sediments are the earth's largest store of carbon, mostly in carbonates. 

Over millions of years, some of the carbon in deeply buried deposits of dead plant matter and algae have been converted into carbon-containing fossil fuels such as coal, oil, and natural gas. In a few hundred years, we have extracted and burned huge quantities of fossil fuels that took millions of years to for. This has added large quantities of CO2 to the atmosphere and altered the carbon cycle. In effect, we have been adding CO2 to the atmosphere faster than the carbon cycle can remove it. 

As a result, levels of CO2, in the atmsophere have been rising sharpy since about 1960. There is considerable scientific evidence that this disruption of the carbon cycle is helping to warm the atmosphere and change the earth's climate. Another way in which we alter the cycle is by clearing carbon-absorbing vegetation from forrests, especially tropical forest, faster than they can grow back. This reduces the ability of the carbon cycle to remove excess CO2 from the atmosphere and contributes to climate change.