What are the main sources of carbon dioxide emissions?
Since the Industrial Revolution, human activities such as the burning of oil, coal and gas, as well as deforestation have greatly increased CO2 concentrations in the atmosphere. As we can see from figure 1, almost all human CO2 emissions (about 87%) come from fossil fuels use. The 3 types of fossil fuels that are used the most are coal, natural gas and petroleum. When fossil fuels are combusted, the carbon stored in them is emitted almost entirely as CO2.1
The three main sectors that use fossil fuels are:
- Utilities (power, gas, oil etc...)
- Industrial production
Figure 1:Source: Inventory of U.S. Greenhouse Gas Emissions and Sinks (2008), EPA.
An important source of human CO2 emissions worldwide is caused by the transportation of goods and people. The emissions caused by people traveling (by car, plane, train, etc...) are examples of direct emissions since people can chose where they are going and by what method.
The emissions caused by the transportation of goods are examples of indirect emissions since the consumer has no direct control of the distance between the factory and the store. Since the distance between the manufacturer and the consumer is constantly growing, more pressure is put on the transportation industry to bridge this gap and this ends up creating more indirect emissions. What's worse is that 99% of the energy used to transport people and goods all over the world comes from the combustion of fossil fuels.
Figure 2:Source: Inventory of U.S. Greenhouse Gas Emissions and Sinks (2008), EPA.
Figure 2 highlights one of the most alarming trends in today's modern economy. The impact that transporting people and goods has on greenhouse gas emissions and climate change is so large that it has surpassed emissions from all industrial manufacturing. This trend started in the 1990's and has continued ever since causing an increase in indirect emissions.
The fact of the matter is that a person can only travel so much before they get exhausted but manufactured goods can travel limitless distances. U.S. automobiles, motorcycles, trucks, and buses drove over 2.8 trillion miles in 2002. That's almost 1/12th the distance to the nearest star beyond the solar system. It's like driving to the sun and back 13,440 times.2
- Utilities (power, gas, oil etc...):
Depending on the energy mix of your local power company you may find that the electricity that you use at home and at work has a considerable impact on greenhouse gas emissions. All industrialized nations (with the exception of Canada and France) get the majority (between 60-80%) of their electricity from the combustion of fossil fuels. Below is a chart for all G8 nations, for the complete list of all nations click here.
- Industrial production:
Manufacturing and industrial processes all combine to produce large amounts of each type of greenhouse gas but specifically large amounts of CO2 because of two reasons. First, many manufacturing facilities directly use fossil fuels to create heat and steam needed at various stages of production. Second, their energy intensive activities use more electricity than any other sector so unless they are using renewable sources the energy that they use is responsible for vast amounts of emissions.
By industrial production we are mainly talking about manufacturing, construction, mining, and agriculture. Manufacturing is the largest of the 4 and can be broken down into 5 main categories: paper, food, petroleum refineries, chemicals, and metal/mineral products. These categories account for the vast majority of the energy use and CO2 emissions by the sector.3, 4
|Electrical Energy Produced By Fossil Fuel Combustion|
|G8 Nation||Fossil Fuel Combustion||Total||%|
Source: International Energy Database (2008), Energy Information Administration
1 U.S. Department of Energy, Energy Information Administration, Carbon Dioxide Information Analysis Center
2U.S. Department of Energy, Transportation Energy Data Book: Edition 26 2007.
3U.S. Department of Energy, Energy Information Administration. Annual Energy Review 2004.
4U.S. Department of Energy, Energy Information Administration. Manufacturing Consumption of Energy 2002.