Where are greenhouse gases coming from?

The main greenhouse gas in our atmosphere is carbon dioxide (CO₂).  Carbon dioxide resulting from the combustion of petroleum, coal, and natural gas makes up 56.6% of all global anthropogenic greenhouse gas emissions.  17.3% of all global anthropogenic greenhouse gas emissions come from CO₂ as a result of deforestation, decay of biomass, etc.  Another 2.8% is also from CO₂ resulting from “other” activities such as cement production and natural gas flaring.

The next main greenhouse gas that is emitted is methane (CH₄).  Methane makes up roughly 14.3% of global anthropogenic greenhouse gas emissions.  Methane is produced from agriculture, oil and natural gas operations, coal mines and landfills.

Another main greenhouse gas produced by humans is nitrous oxide (N₂O), which makes up 7.9% of emissions.  Nitrous oxide comes from burning fossil fuels, the use of nitrogen fertilizers and certain industrial and waste management processes.

The last 1.1% of global emissions comes from several different fluorocarbons that are released as a result of various industrial processes.  Figure 1 below illustrates the above information in the form of a chart.

 Figure 1. Global Anthropogenic Greenhouse Gas Emissions in 2004

  

The next figure presents data on the major global sources of carbon dioxide (CO₂) emissions by country, from the beginning of the Industrial Revolution to the present. 

Figure 2. Global CO₂ Emissions from 1752-2006

Figure 3 is a graph that presents the global carbon emissions by fuel type from 1800-2007 in million metric tons of carbon, as reported by the Carbon Dioxide Information Analysis Center.

Figure 3. Global fossil carbon emission by fuel type