Greenhouse gas emissions are mainly caused by burning fossil fuels for our cars, trucks, ships, trains and planes. Carbon dioxide (CO2) is the most significant contributor, accounting for approximately 76 percent of total emissions. Methane, mainly from agriculture, makes up 16 percent of the total, while nitrous oxide, mainly from industry and agriculture, contributes 6 percent. All figures are expressed in CO2 equivalents.Human activities are responsible for almost all of the increase in greenhouse gases in the atmosphere over the past 150 years.
In the United States, burning fossil fuels for electricity, heat and transportation is the largest source of emissions.
Methane from livestock and rice cultivation accounts for 35 percent of greenhouse gas emissions from the food system and is generally similar in developed and developing countries. When electricity emissions are allocated to the end-use sector, industrial activities account for a much larger proportion of emissions. Burning petroleum fuels and non-biomass waste (mainly plastics) in waste-to-energy power plants and emissions from some types of geothermal power plants account for approximately 2 percent of CO2 emissions from the energy sector. Packaging also accounts for a similar proportion of emissions, or about 5.4 percent.A small number of countries contribute most of the world's greenhouse gas emissions, with the top 10 emitters accounting for more than two-thirds of annual global greenhouse gas emissions.
In the US, transportation is responsible for the bulk of emissions.
