Greenhouse Gas: Carbon Dioxide
Share of Global GHG Emissions: 25-30%

Futtsu Thermal Power Station near Tokyo. Generating electricity and heat by burning fossil fuels like coal, natural gas and oil produces more greenhouse gas (GHG) emissions than any human activity, accounting for at least one quarter of all global emissions. CO2 emissions from electricity and heat have increased as coal has been the fastest growing energy source since 2000, reports the International Energy Agency.

However, the demand for that energy comes from other sectors, such as residential housing or industry. Consequently, this photo gallery presents 14 other sectors' contributions to global emissions (some of which may be subsets of power plant emissions) to get a more detailed picture. Hence the total of all 15 'Share of Global GHG Emissions' figures exceeds 100%. It draws on analysis by consultancy Ecofys based on 2010 data from multiple agencies.

Greenhouse Gas: Carbon Dioxide
Share of Global GHG Emissions: 11%

The largest single source of global emissions, according to calculations by Ecofys, is our homes. Residential buildings demand heat as well as electricity for the increasing numbers of electrical devices used in homes, such as air conditioners and domestic appliances.

Consequently, making the housing stock as energy-efficient as possible is one of the most effective ways to rapidly reduce emissions. More efficient appliances, better insulated buildings, and improved or alternative energy systems are all necessary solutions.

The Ecofys research emulates and updates work by the World Resources Institute in 2005 which identified global emissions by sector based on data from the year 2000. Ecofys used data from the International Energy Agency, the Global Carbon Project and the European Commission’s Joint Research Centre.

Greenhouse Gas: Carbon Dioxide
Share of Global GHG Emissions: 10.5%

Gridlock on the road into Beijing. There are now well over one billion cars, trucks, and buses on the world’s roads, more than one vehicle for every seven people. The spectacular growth of road transport, driven in recent years by China and other emerging economies, produces over 10 percent of man-made greenhouse gas emissions.

These emissions have increased by over 50% since 1990 despite improvements in vehicle fuel-efficiency and now account for about three quarters of transport emissions, says the International Energy Agency.

Greenhouse Gases: Carbon Dioxide, Nitrous Oxide, Methane
Share of Global GHG Emissions: 10.3%

Virgin Amazon rainforest borders an area of jungle destroyed to make way for farms in Brazil. Deforestation, forest degradation and decay, forest and peat fires and other land use changes are responsible for over 10 percent of global emissions.

The damage done is two-fold: first, the capacity of forests to absorb CO2 and act as the Earth’s lungs is diminished; second, large amounts of climate-warming CO2, methane and nitrous oxide stored in trees and soils are released into the atmosphere. 

Greenhouse Gases: Carbon Dioxide, Methane
Share of Global GHG Emissions: 8.3%

A significant part of the energy industry’s carbon footprint consists of its own use of fossil fuels in its processes as well as the ‘losses’ incurred through leakages from pressurized equipment in power plants and refineries as well as activities like flaring or venting gases from drilling or mining operations. The United Nations Environment Programme estimates that up to 6% of global emissions are ‘fugitive emissions’ from these and other processes.

Greenhouse Gas: Carbon Dioxide
Share of Global GHG Emissions: 7%

Alongside the residential sector, construction and operation of commercial and public buildings contributes a significant portion of global emissions, particularly with the growth of electrically-driven industrial processes, the requirement to heat or cool workplaces and the increasing need for computing power and storage capacity. By 2035, the International Energy Agency projects that demand for electricity will be almost 70% higher than current demand.

Greenhouse Gas: Carbon Dioxide
Share of Global GHG Emissions: 6%

A laborer walks over newly made pipes at a cement plant in Yingtan, China. There is increasing global demand for cement, bricks, wall and floor tiles due to a construction boom in emerging economies in particular.

Cement production is very energy intensive, requiring first the quarrying of limestone and then processing of that limestone at very high temperatures. CO2 emissions are also generated by carbonate oxidation in the cement clinker production process, the largest non-combustion source of CO2 from industrial manufacturing. Other ‘non-metallic minerals’ like ceramics and glass also involve transforming minerals like limestone, silica and clays using energy-intensive processes.

Greenhouse Gas: Methane
Share of Global GHG Emissions: 5.5%

A cow in Argentina has its methane belches collected in a plastic tank. Argentine scientists say cows could be generating 30% of Argentina’s emissions. Almost half of all global methane emissions come from belching livestock and their manure, making livestock farming a significant contributor to climate change.

Methane is twenty times more potent as a greenhouse gas than CO2 although it does not last as long in the atmosphere, eventually breaking down into carbon dioxide and other gases.

Greenhouse Gas: Carbon Dioxide
Share of Global GHG Emissions: 4.8%

The iron and steel industry has one of the largest carbon footprints of any single industrial sector and is growing in tandem with other construction and infrastructure-related industries like cement making. It significantly increased its share of global emissions from 3.2% in 2000 to 4.8% in 2010.

The sector requires several energy-intensive processes including mining and transporting iron ore, smelting the ore into iron in blast furnaces and then turning the iron into steel.

Greenhouse Gases: Carbon Dioxide, Nitrous Oxide
Share of Global GHG Emissions: 4.4%

Plowing the ground releases carbon dioxide from the soil into the air. Modern agriculture also relies heavily on fertilizers and pesticides, which release nitrous oxide into the air. Nitrous oxide is 300 times more potent than carbon dioxide as a warming agent although it does not last as long in the atmosphere.

Ecofys estimates that manipulating agricultural soils is responsible for 4.4 percent of emissions worldwide, with energy use in agriculture responsible for a further 1.4% of the global total.

Greenhouse Gas: Carbon Dioxide
Share of Global GHG Emissions: 4.3%

The manufacture of industrial chemicals and petrochemicals which provide the building blocks for plastics, textiles, dyes and resins, detergents, fertilisers and tens of thousands of other products happens at very large scale in chemical and petrochemical plants. These require large amounts of energy to power high temperature processes like ‘steam cracking’ which transform raw materials such as petroleum or natural gas into the desired products.

Greenhouse Gases: Carbon Dioxide, Methane
Share of Global GHG Emissions: 3.1%

An oil platform stands in the Norwegian sector of the North Sea. Extracting, transporting, refining and processing oil and natural gas requires large amounts of energy and involves considerable risks of leakage of ‘fugitive emissions’ at each stage, particularly as the industry looks to drill in more demanding environments such as deep offshore.

However, comparing the Ecofys analysis with the World Resources Institute data from 2000 shows the industry’s share of global emissions has more than halved from 6.4% to 3.1%.

Greenhouse Gases: Methane, Carbon Dioxide
Share of Global GHG Emissions: 3%

A man scavenges for waste to recycle at a garbage dump in Linfen, China. Landfill sites like this produce greenhouse gases because rotting organic waste like food waste emits methane which warms the atmosphere unless it is captured. Advanced industrialsed countries like the United States, the UK and Japan throw away between 20% and 30% of edible food.

Processing waste water also produces methane. If garbage is burned, however, it emits CO2. Almost everything we produce, consume and throw away, including human waste, results in some greenhouse gas emissions.

Greenhouse Gases: Methane, Carbon Dioxide
Share of Global GHG Emissions: 1.8%

Coal mining produces methane as ‘fugitive emissions’ because methane absorbed by the coal is released from coal seams when they are fractured or disturbed. Surface mining releases methane directly into the atmosphere whilst methane remaining in the coal can be released during the subsequent processing and transportation.

Greenhouse Gases: Carbon Dioxide, Water Vapor, Nitrous Oxide, Aerosols
Share of Global GHG Emissions: 1.5%

A jet airliner leaves condensation trails in the sky. The trails are formed by soot and water vapor from the plane engines which burn kerosene. Aircraft emissions of water vapor, nitrous oxides, aerosols and CO2 at altitude could be two to four times stronger than emissions of CO2 alone.

Aviation is responsible for about 1.5 percent of man-made global warming and emissions from aviation grew even faster than those from road transport between 1990 and 2011, according to the International Energy Agency.