The keywords “greenhouse gases”, “global warming” and “climate protection” are on everyone’s lips nowerdays- but what do we understand by these terms, how are they meant? In the following we give a brief overview of these topics.

Greenhouse gases are gases that contribute to the earth’s greenhouse effect and can be of both natural and human origin. A certain amount of natural greenhouse gases in the atmosphere is necessary for the existence of life on earth.

The current increase of the concentration of greenhouse gases (especially CO₂) caused by human activities, however, intensifies the natural greenhouse effect and leads to global warming of our planet, which in turn will have numerous consequences.
Global warming will affect us all and change our lives on earth forever. That is why today one of the most important tasks of humanity of our century is to protect the planet’s climate. The goal is to establish binding rules for all states of the earth in order to halt global warming caused by humans and the industry.


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Greenhouse gases (GHG) are (trace-) gases that contribute to the greenhouse effect of the earth (or other planets) and can be of both, natural and anthropogenic origin. They absorb part of the energy of the long-wave (infrared) radiation (thermal radiation), that is reflected by the ground, which would otherwise escape into space. Most of the energy they absorb is emitted again as thermal radiation. The part of which directed towards the earth is called “atmospheric counter radiation”. It is heating the earth’s surface in addition to direct sunlight. This is what is known as the greenhouse effect.

Natural greenhouse gases, especially water vapor, make the average temperature near the earth’s surface rise. Without this natural greenhouse effect, the global average temperature on the earth’s surface would be an icy −18° C, which would make life on earth hardly possible. That means that we need a certain amount of natural greenhouse gases in the atmosphere and that they make life on earth in its present form possible. However, anthropogenic (man-made) greenhouse gases are increasingly being added to the natural greenhouse gases, and they hold back more and more of the radiation, that is reflected from the earth’s surface.

The term greenhouse gases refers to various gaseous substances, such as:

  • Carbon dioxide CO2
  • Ozone O3
  • Nitrous oxide N2O
  • Methane CH4

The atmosphere that is surrounding our planet earth is vital to us. It protects us against harmful radiation and balances out the temperature differences between the poles and the equator. This thin layer of gas that surrounds us consists mainly of nitrogen and oxygen. But there are also other gases in the atmosphere. Since these only occur in very low concentrations, they are summarized under the term trace gases. The natural composition of dry air[in Vol.%] :

Oxygen (O2)21.93
Nitrogen (N2)78.10
Argon (Ar)0.93
Carbon dioxide (CO2)0.03
furthermore H2, Ne, He, Kr, Xe
as well as the trace gases:
H2O, O3, CO, SO2, NO, NO2, N2O, CH4, NH3, hydrocarbons (HC), CHC, CFC, etc.

The following table gives an overview of the various trace gases, their origin and their occurrence:

trace gasnatural occurence
anthropogenic occurence
CO2respiration, microbial degradation of biomass, fossil fuels, deforestation
H2Oevaporation from waterT*: negligible S**: air traffic
O3T*: oxidation processes S**: photochemical processesT*: vehicle exhaust gases S**: none
N2Obacterial activitynitrogen fertilization
CH4bacterial activityRice cultivation, livestock farming, landfills, use of biomass
NH3bacterial activitylivestock farming, fertilization, sewage treatment plants
COoxidation of hydrocarbons, forest firesfossil fuels
HFCnopropellant, coolant
HFCnoaluminum production, semiconductor production, fire protection, extinguishing agents
SF6noelectrical industry, insulation gas (e.g. for soundproof windows)
NF3noproduction of flat screens and solar cells

*T = troposphere (lowest layer of the earth’s atmosphere in which the weather processes take place) **S = stratosphere (middle layer of the earth’s atmosphere – approximately between 11 and 50 km altitude)

The greenhouse gases found in the earth’s atmosphere mainly include water vapor (N2O), carbon dioxide (CO2), ozone (O3), nitrous oxide (laughing gas, N2O) and methane (CH4). In total, they only have a mass of about three per thousand, but are extremely effective in terms of radiation. Without them, the heat radiation from the sun, would escape unstoppeded escape into space again. The natural greenhouse effect caused by them is a phenomenon, that occurs independently of humanity’s effects on the planet, but it makes life on earth as we know it possible in the first place.

The climatic conditions on the ground are mainly determined by two factors:

  • the intensity of solar radiation on earth
  • the composition of the earth’s atmosphere

Each of the gases mentioned above has different ranges, that are defined by their wavelengths, in which they absorb and emit radiation. These wavelength ranges can be compared with blinds that close parts of the window (of the earth’s atmosphere) or at least make them less permeable. This window is primarily made smaller by the water vapor in the atmosphere. Water vapor, the most important greenhouse gas by far, only allows energy to escape into space in two narrow areas. Just in the first of the remaining window sections carbon dioxide and nitrous oxide absorb the radiation energy, in the second one energy is absorbed by ozone. In both window sections, there is also a dampening of the radiation caused by methane. The water vapor thus has the largest impact within the natural greenhouse effect, ahead of carbon dioxide, ozone, nitrous oxide and methane.

With the beginning of industrialization (around the year 1750), the concentration of radiation-active trace gases (except ozone) in the atmosphere increased more and more.

Carbon dioxide is the most important one amongst them. It is emitted, when fossil fuels such as coal, petroleum or natural gas are burned to generate energy.

But the amounts of methane and nitrous oxide in the atmosphere, which are produced in animal husbandry, for example, are also increasing steadily.
And last but not least, with the fluorinated greenhouse gases, new, artificially generated greenhouse gases enter the atmosphere and intensify the greenhouse effect as well.

This anthropogenic part of the greenhouse effect is having an increasing impact on the climate of our planet and as a consequence the average temperature on the earth’s surface is rising.

In 2018, 6% more CO2 was emitted than in the previous year (37.9 gigatons per year). The carbon dioxide emissions thus reached a new record: They were around 67% higher than in 1990 (the reference year of the Kyoto Protocol).

Despite global efforts to protect the climate, the consumption of coal, oil and natural gas is still increasing.


As already mentioned, the warming of the earth by greenhouse gases is a partially natural process. Strictly speaking, the term global climate change therefore does not only refer to the changes in the global climate caused by humans, but also to the warming of the earth through recurring natural climate fluctuations.

However, the current increase in the concentration of various greenhouse gases, especially carbon dioxide, that is caused by human activities, amplifies the natural greenhouse effect severely.


Global warming will affect us all and permanently change our life on earth.

Some researchers assume that the average temperature on earth will rise between 2 and 4.5 degrees Celsius over the next one hundred years. This rise in temperature is in part already noticeable today. For example, the ice volumes at the poles of the planet continue to melt, which will ultimately have devastating consequences for people, animals and plants. Because when the polar ice melts, not only does the sea level rise, but also

  • the albedo effect (the reflection of e.g. incident solar radiation) decreases with the disappearing of the white surface of the ice
  • and dark water surfaces, which are no longer covered by ice, warm up, which causes methane to escape into the atmosphere from greater depths,
  • Furthermore, cold meltwater slows the Gulf Streams
  • and permafrost soils begin to thaw in summer, which also causes a release of methane into the atmosphere.

All these changes in the global ecosystem are ultimately contributing to global warming. That is referred to by cascading tipping points.

Humanity will have to prepare for profound changes in its sourrounding environment. The rise of the sea level will lead to changes in the coastal strips. Weather extremes, which can already be observed, such as storms, floods and extreme droughts, will increase. Parts of the tropical zone will no longer be habitable.

The consequences of global warming could be a greater threat, than just being one of the biggest economic crises in modern history.


The effects of global warming can vary severely between different regions. This is particularly evident in terms of temperature, the amount of precipitation and the climatic water balance.

In general, it can be summarized:

Global warming affects …

The consequences will have an impact on health, water supply and nutrition of the world’s population. Livelihoods will be lost through floods as well as droughts.

Global warming and its consequences are rapidly accelerating species extinction. Most animal species cannot adapt quickly enough to the new conditions. In addition, through deforestation, drainage, agriculture, cattle breeding and urban development, humans continue to intervene in the habitats of numerous species. These interventions not only destroy habitats, but also interrupt food chains.

Deserts will continue to expand due to higher temperatures and decreasing groundwater reservoirs. The people living in these regions are losing land for agriculture and animal husbandry as well as living space.

In contrast, entire coastal regions could be flooded by rising sea levels.

The industrialized countries cause the largest percentage of greenhouse gases in the atmosphere. An average German person emits around 10 tons of CO2 per year, while the average Ethiopian citizen only emits 0.05 tons. However, developing countries have little or no budget for environmental protection, while the climate impacts for the people in these countries are life-threatening. More than 20 million people are already fleeing their homes every year, because of the effects of climate change. Climate change is massively exacerbating the injustice between rich and poor countries.

Representatives of most of the countries on earth meet annually for a climate conference with the goal to establish binding rules for all countries to put a stop to global warming caused by humanity. So far, however, it has not been possible to agree on a joint approach that could be described as a satisfactory answer to the aforementioned challenges.

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