The greenhouse effect is a necessary and positive climatic phenomenon, of heating the lower layers of the earth’s atmosphere, produced by the absorption by several gasses of infrared radiation emitted by the Earth.

This effect consists in the capture of the heat, thanks to the molecules that are found in the air.

One type of molecule passes solar radiation undisturbed towards the Earth, while a second type instead retains and absorbs the thermal radiation and the heat coming from the Earth, itself.

The greenhouse effect is of fundamental importance for living organisms, since reducing the dispersion of heat determines the maintenance of a constant temperature of the Earth.  Without the natural greenhouse effect, there would be no life.

The gases that have always contributed to this natural effect are primarily water vapor (H2O), carbon dioxide (CO2), ozone (O3), methane (CH4) and nitrous oxide (N2O).

Without these gases the average temperature on the earth’s surface would be around -18 ° C.

The average temperature is instead around +15 ° C.

The natural greenhouse effect therefore entails an increase of [15 – (- 18)] = 33 ° C.

Carbon dioxide (CO2) has a key and predominant role on the natural greenhouse effect. It acts as a solar radiation filter. It allows short-wave energy (incident) to pass through [UVA and UVB] and instead absorbs long-wave energy, ie the thermal radiation emanating from the earth towards outer space.

In recent years, this effect has increased due to the introduction of large quantities of greenhouse gases into the atmosphere by humans.

Causing the increase of the greenhouse effect are: carbon dioxide (CO2 with a reference GWP always equal to “1,” both at 20 years, and at 100 years, and at 500 years), methane (CH4 with a 100-year GWP of 25), nitrous oxide (N2O with a 100-year GWP of 298), sulfur hexafluoride (SF6 with a 100-year GWP of 22,800), hydrofluorocarbon (HFC-23 with a 100-year GWP of 14,800), hydrofluorocarbon (HFC-125 with a 100-year GWP of 3,500) and perfluorocarbon (PFC -14 with a 100-year GWP of 7390), perfluorocarbon (PFC-116 with a GWP at 100 years of 12,200). Source IPCC [ Integrated Pollution Prevention and Control ] 2007


GWP Global Warming Potential expresses the contribution to the greenhouse effect of a greenhouse gas relative to the effect of CO2, whose reference potential is equal to 1. For example, nitrous oxide, N2O for example, has a GPW (100 years) equal to 298; this means that a tonne of nitrous oxide emitted into the atmosphere causes an increase in the greenhouse effect equal to that caused by the emission of 298 tons of CO2.

The use of GWP weight factors allows, therefore, both combining of emissions of individual greenhouse gases and to evaluate global warming, and to identify the contributions of the individual emission sources to the overall formation of greenhouse gases.. [Source Arpa Lombardia = Regional Agency for Environmental Protection]


Much of the responsibility must be attributed to the production of energy from fossil fuels.

The main “greenhouse gas” comes from the combustion of coal, oil and methane. The activities of thermoelectric power plants, the introduction of combustion fumes produced by industry and the discharge of car exhausts into the atmosphere increase the production of carbon dioxide (CO2).



The greenhouse effect can be contained through:

  • Reduction of consumption, using energy in a more rational and intelligent way;
  • The construction of machines and appliances with high yields;
  • The promotion of the exploitation of renewable energies (water power, solar collectors, photovoltaic panels, biomass, wind, air, waste water derived from production processes);
  • Investment in the search for energy efficiency
  • Informing citizens in an objective and constant manner on all the problems and new energy and environmental solutions.


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