Everybody talks of the greenhouse effect, not always with competence, so that it seems a fashion among scientists, environmentalists, politicians, intellectuals and common people but the reality is not like this because the greenhouse effect is already active, with a decisive acceleration in the last 20-30 years.
Its effect is that of heating of the whole climate of our planet, widely recorded and studied by scientists of all the world, although the time range object of these studies is still too short to fully understand it and make precise forecasts for the future.
In the practice, our atmosphere creates in any case a greenhouse effect for its presence, given that the Moon, without any atmosphere, has an average tempereature (T) of about -18C while this average value on the Earth is +15C.
In constant conditions, this normal greenhouse effect is just what allows life to develop as we know it today but, if the composition of our atmosphere changes for whatever reason (natural or human-made), making increase the presence of some gases, it happens that the climate on the whole planet starts to become warmer and unstable, breaking most of the equilibria existing to date in the natural environment.
The gases that are surely guilty of making our atmosphere as a warmer and warmer greenhouse are CO2 (CARBON DIOXIDE or CARBON ANYDRIDE), today forming the 0.032% of our atmosphere but nearly doubled in the last century because of the massive hydrocarbons combustion and fermentations produced by our industries, power plants, vehicles, heating systems and by the same agriculture that are continuing to increase.
Another important gas responsible of this "global warming" (another term nearly abused today) is METHANE (CH4), produced by our fermentation processes, like that of animals excrements in the industrial breeding farms (15-20% of all CH4 released in the atmosphere) and the discharges and leaks of fossil fuels reforming.
So, every year, CH4 in the atmosphere increases its amount of 1%.
These gases contribute by reflecting toward the ground part of solar light that the earth surface (lands or oceans) reflects toward the outer space in the wavelenght range of infrared radiations (IR), emitted by every object at
T > -273.16C, the absolute zero.
Just CO2 and CH4 (and also NOx and CFC) hold more heat in the low layers of the atmosphere, below 19 Km of height, in what is named TROPOSPHERE and this effect is cumulative.
The consequent warming makes eveporate more water vapour from oceans and increases its amount in the atmosphere accumulating energy in it in the form of heat and pressure gradients, the driving force of all atmospheric phenomena (thunderstorms, hurricanes, tempests, draughts and monsoons).
More water vapour is also considered a further contribution to the greenhouse effect, because also this gas absorbs IR radiation, particularly between 4000 and 7000 nm (nanometres), while CO2 absorbs it in the range 13,000-19,000 nm and the atmosphere remains totally transparent in the range 7000-13,000 nm.
Even if greenhouse gases production were stopped now, the gases already released to date would heat of 0.5C the atmosphere within 2100, as affirmed in a study by the US National Center for Atmospheric Research (NCAR) in 2005.
Another very worrying contribution to the greenhouse effect is the decreased absorption of CO2 by the forests of all the world that fix it in their tissues and release O2 and water vapour.
Forests, in fact, keep on being cut or burned by legal and illegal activities to get more and more soil for agriculture, breeding, buildings and wood for industry in the rich Countries; the more we reduce forests, the less they can absorb the excess of CO2.
So, just while we produce more and more CO2, we progressively destroy what can absorb it. Pure madness.
The only result of this consumption of our natural resources will be a climatic disaster, if CO2 emission from human activity would continue at the present rate, this gas would be the double within the next 100 years; furthermore, also considering the simultaneous increase of CH4, H2O and NOx (nitrogen oxides, other greenhouse gases), this double concentration could be reached within only 50 years.
This would cause an average increase of the average atmospheric T of 2.5-6.0C in the same period, with the consequent increase of draughts in some areas and floods and tempests in others, the melting of all glaciers within the end of this century and that of a good portion of polar ice caps.
This will cause an increase of oceans level of many metres and the consequent submersion of many islands and coastal plains.
Scientists still don't agree on the quantitative prediction of global warming and its consequences, but they all agree on the fact that the greenhouse effect will be more and more evident in the next future.
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