What causes the greenhouse effect

Bavarian State Office for

The atmosphere that envelops planet earth is vital to us. It protects against harmful radiation and balances out the temperature differences between the poles and the equator. The thin gas layer consists mainly of nitrogen (78 percent) and oxygen (21 percent). There are also other gases in the atmosphere. Since these only occur in low concentrations, they are summarized under the term trace gases.

The earth's atmosphere needs protection; Photo: © @nt - Fotolia.com

Some gases in the atmosphere act as greenhouse gases. They allow sunlight to pass through almost unhindered, but hold back the thermal radiation that emanates from the earth's surface in the atmosphere. The main contributor to this natural greenhouse effect is water vapor (H.2O), followed by the gases carbon dioxide (CO2), Ozone (O3), Nitrous oxide (N.2O) and methane (CH4). The greenhouse effect is what makes life in its present form possible: Without it, the average temperature on our planet would be an icy minus 18 degrees Celsius.

Greenhouse gases in abundance

Since the beginning of the industrial age around 1750, the concentration of greenhouse gases in the atmosphere has increased more and more. This increases the natural greenhouse effect and the average temperature on earth rises. This anthropogenic - that is, man-made - greenhouse effect changes the climate on our planet.

Above all, the proportion of carbon dioxide has risen sharply since industrialization: the gas is released when coal, crude oil or natural gas are burned to generate energy. But the amount of methane and nitrous oxide, which are produced in animal husbandry, for example, has also increased. Last but not least, with the fluorinated greenhouse gases (F-gases), new, artificially generated greenhouse gases enter the atmosphere. According to the Federal Environment Agency, 87.9 percent of the greenhouse gases released in Germany in 2014 were carbon dioxide, 6.2 percent methane, 4.3 percent nitrous oxide and 1.6 percent F-gases.

Energy from fossil fuels harms the climate; Photo: © TTstudio - Fotolia.com
Modern cars emit fewer emissions. But the traffic is increasing - and with it the burden; Photo: © Sergiy Serdyuk - Fotolia.com

Kyoto Protocol: "Black List" for Greenhouse Gases

By signing the Kyoto Protocol, 191 countries and the European Union committed themselves to reducing greenhouse gas emissions. The Kyoto Protocol originally covered six greenhouse gases, in 2013 nitrogen trifluoride (NF3).

How much a greenhouse gas contributes to global warming is shown by its specific global warming potential (also: Global Warming Potential or GWP value). The effect of carbon dioxide on the climate is used as a benchmark: For example, one kilogram of methane has an impact on the climate 25 times as much over a period of 100 years as the same amount of carbon dioxide. In order to be able to better compare the sum of different greenhouse gas emissions, these are therefore converted into CO2-Equivalents specified.

Greenhouse gasGlobal warming potential (in CO2-Equivalents), source: 4th IPCC Assessment Report, 2007 Important sources
Carbon dioxide (CO2)1Fossil energy sources
Methane (CH4)25Cattle farming, rice cultivation, use of biomass
Nitrous oxide (N.2O)298Fertilizer, fossil fuels
Fully halogenated hydrocarbons (PFC)7.390 - 12.200Aluminum production, semiconductor production, fire protection, extinguishing agents
Partially halogenated fluorocarbons (HFCs)124 - 14.800Coolant, propellant (e.g. in sprays)
Sulfur hexalfluoride (SF6)22.800Electrical industry, insulation gas (e.g. for soundproof windows)
Nitrogen trifluoride (NF3)17.200Production of flat screens and solar cells

Additional information