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Greenhouse effect

Global warming is caused by increasing emissions of greenhouse gases. These gases form a layer like glass above the Earth, trapping heat from the sun. This is why this phenomenon is called the greenhouse effect.

Without the greenhouse effect there would be no life on Earth, and the Earth would have an average temperature approximately 33°C colder. The greenhouse effect results from the composition of the atmosphere, and has probably existed as long as the Earth has had an atmosphere.

However, the greenhouse effect is currently being magnified as a result of greenhouse gas emissions from human activities. The most significant anthropogenic greenhouse gases are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). These are followed by the industrial gases, such as CFCs and HCFCs, PFCs and SF6. Finally, ozone – primarily formed due to air pollution in the lower atmosphere – also acts as a greenhouse gas.

Human activity has increased the atmospheric concentrations of these greenhouse gases. The concentration of CO2 is at the highest level it has been for the last 420,000 years.

  • Greenhouse gases
    Greenhouse gases

    Greenhouse gases permit shortwave radiation from the sun to pass relatively unhindered through the Earth’s atmosphere, but absorb much of the long-wave heat radiation reflected by the earth when it is hit by sunlight.  

Facts

IPCC
Intergovernmental Panel on Climate Change is the UN panel of climate.
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ppm
Parts pr. million. The relative quantity of molecules per one million molecules, of a substance.

ppb
Parts pr. billion. The relative quantity of molecules per one billion molecules, of a substance.

CO2 eq
CO2 equivalent is a conversion of the various greenhouse gases to the amount of CO2 that have similar greenhouse effect.
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