Global Climate Change

Topics
What is global climate change?
Human activity and CO2 emissions

What is global climate change?

Global climate change is the result of an average rise in global air temperatures caused by increased concentrations of greenhouse gases in the atmosphere. Methane, carbon dioxide, water, and nitrous oxide are all considered greenhouse gases because, when in the atmosphere, they absorb solar radiation and have a general warming effect on the atmosphere. In nature, the atmospheric concentrations of these gases are always in flux, which causes a change in global temperature and global climate, along with other factors. Since the start of the industrial revolution, humans have played a significant role in this once natural process By consuming fossil fuels, humans have increased atmospheric concentrations of greenhouse gases. Because fossil fuels experience incomplete combustion, they release unused carbon atoms into the atmosphere which combine with oxygen to form carbon dioxide. This rapid use of fossil fuels has led to increased atmospheric carbon concentrations over the past hundred years that is far more drastic than the natural flux that has existed for thousands of years (see Figure 1). A similar increase in average global atmospheric temperature has also been witnessed during this time period. Scientific consensus now says that human-caused increases in carbon dioxide are directly associated with rising global temperatures (see Figure 2). Figure 1: Earth's surface temperatures have been increasing rapidly in recent years. Figure 2: Temperature increases are correlated with rising carbon dioxide concentrations. Human Activity and CO2 Emissions We naturally produce carbon dioxide as a production of respiration as we breathe. Our exhalation of carbon dioxide is balanced by a number of natural processes such as photosynthesis. However, since the industrial revolution human activities have dramatically increased carbon dioxide emissions into the atmosphere, upsetting this balance. Furthermore, although it is not addressed here, deforestation reduces the rate at which carbon dioxide is converted into oxygen. In the United States, 98% of carbon dioxide is emitted as result of the combustion of fossil fuels. The combustion of fossil fuels can be divided into four sectors. When considering an individuals’ share of carbon dioxide one should make sure to account for the carbon dioxide emitted to supply the goods and services that person uses. For example, one should consider the carbon dioxide emitted as a result of building the car a person buys. Figure 3. Emissions of Carbon Dioxide by Sector in the United States Transportation - 32% The transportation sector is responsible for the largest share of carbon dioxide emissions. Within this category, the primary sources of carbon dioxide emissions are automobiles and trucks though other means of transportation such as trains, planes and ships also produce carbon dioxide. Industry – 29% The majority of carbon dioxide produced within industry is for the manufacturing of various products from paper to plastics, sidewalks to satellites. Residential – 21% The majority of the carbon dioxide emissions within the residential sector are a result of generating the electricity for domestic uses such as air conditioning, lights and appliances. The second largest source of residential carbon dioxide emissions is from the combustion of natural gas, primarily for heating. Commercial – 18% Maintaining a suitable indoor environment in structures such as office buildings or stores via lighting, heating, ventilation and cooling accounts for the majority of commercial carbon dioxide emissions. Sources: Energy Information Administration. Emissions of Greenhouse Gases in the United States - Carbon Dioxide Emissions. Modified 28 April 2004. Energy Information Administration. Emissions of Greenhouse Gases in the United States 1998 - Carbon Dioxide Emissions. Modified 29 October 2000.