One of the main greenhouse gases, carbon dioxide, CO2, is a colorless, odorless gas that is naturally emitted from the earth’s surface, as well as through the human function, respiration, and the plant function, photosynthesis. Carbon dioxide is released during exhalation and is used by plants as a necessary component for photosynthesis, which yields glucose, a carbohydrate that must be consumed by humans in order to have energy. The natural release of carbon dioxide is represented in the two diagrams below, which depict photosynthesis and respiration:
This photo shows the cycling of carbon dioxide during the process of photo synthesis.
Image Credit: http://farm4.static.flickr.com/3217/3081218761_d6d4aa2f72_o.gif
This second figures provides a source for visualizing the natural path of carbon dioxide.
Image Credit: http://susty.com/image/atmospheric-carbon-dioxide-storage-diagram-plants-decay-dead-organisms-soil-organic-carbon-mineral-sunlight-photosynthesis-co2-cycle-root-animal-respiration-waste-products-fossil-fuel-burning-image.jpg
Aside from these natural processes, carbon dioxide is also emitted through the combustion or burning of fossil fuels such as coal, oil, and natural gas. Combustion occurs when vehicles are driven as well as when power plants and industrial plants are utilized. Combustion, otherwise known as burning, is the greatest source of carbon dioxide emissions globally. Typically, fossil fuels are burnt for electricity generation in homes and buildings, industrial uses, as well as transportation. Petroleum is the largest share of domestic energy demands. Second is coal, followed by natural gas (EPA, 2006). Electricity generation is the largest problem in relation to using petroleum as fuel, rivaled followed closely by industrial processes that use petroleum as fuel as well.
This pie chart can be used to break down carbon dioxide emissions into industrial uses.
Image Credit: http://www.pbs.org/wgbh/pages/frontline/heat/art/graph3.jpg
In addition to the carbon dioxide emissions that result from industrial processes, deforestation is a serious environmental threat in terms of carbon dioxide emissions. Carbon is naturally removed from the atmosphere to be stored in oceans and the soil surrounding the roots of many plants. Areas where carbon is stored are otherwise known as carbon “sinks.” Forested areas are large carbon sinks because enormous amounts of carbon dioxide are naturally stored in the soil, a result of photosynthesis. Because of this, logging is not encouraged as an eco-friendly practice, whether a small number of trees are cut down or a large number. When a large group of trees is removed at once, either deliberately by logging or accidently in a forest fire, it is titled as deforestation. When this occurs, carbon dioxide is released from the soil at rates that are damaging to the environment because there are no longer any trees to contain the carbon dioxide.
Technically defined as the “permanent removal of standing forests,” by the EPA, following the destruction of a forest, typically, a large number of trees are not planted. This lack of growth throws off the equilibrium of the environment, causing massive CO2 emissions though no photosynthesis is occurring in order to utilize the carbon dioxide or trees to store it, thus making deforestation extremely problematic. Normally, forested areas are not precarious because the decomposition that occurs naturally results in the slow release of carbon dioxide. However, in the case of a forest fire or mass logging, carbon dioxide is released at an alarmingly high rate, contributing significantly to the greenhouse effect with the increase. Overall, deforestation is a large contributor to carbon dioxide emissions globally, however in the United States, emissions due to deforestation are not as significant.
This photo depicts a forest fire in Afghanistan, which has lost over 70% of its’ forests due to deforestation.
Image Credit: http://www.martinfrost.ws/htmlfiles/april2008/deforestation1.jpg
Often times, carbon dioxide released from power plants and industrial plants is captured prior to its release. From this point, it is mechanically injected back into the depths of the Earth, far below the surface. This process prevents the CO2 from being released directly into the atmosphere. According to the EPA, industrial processes that can yield carbon dioxide emissions include mineral production, metal production, coupled with the use of petroleum-based products.
A process that is often utilized in order to counteract the emission of carbon dioxide is carbon sequestration. This process is enacted by planting and growing large numbers of trees and other plants in order to absorb or remove CO2 from the atmosphere. Carbon sequestration is an effective method in combating CO2 emissions because the rate of CO2 removal is greater than the rate of CO2 release. Typically, carbon sinks are within agricultural and forestry lands, which are somewhat abundant, therefore absorbing or sequestering carbon dioxide is an extremely viable practice. Within the United States, carbon sequestration decreased greenhouse gas emissions as a whole by 13% in 2006 (United States EPA, 2006). The decrease mostly resulted from forest growth, the increase in forest area, and the increase of carbon storage within wood products.