school energy&environment

Anthropic or natural?

As already mentioned in the previous paragraphs, the greenhouse effect is a natural phenomenon, provoked by a mixture of gases that are present in the atmosphere (and defined greenhouse gases) without which there would not be any life on the Earth. In the last century, however, the intense human production activities led to an increase in the concentration of “greenhouse gases” in the atmosphere. There are two main causes: on one hand the increasing amount of emissions originated prevalently by the traditional processes for the production of energy (fossil fuels); on the other, the progressive destruction of the forests which, thanks to plant chlorophyll photosynthesis, can “absorb” the carbon dioxide in the air and transform it into organic material (leaves, branches and roots), acting as true “tanks” or “sinks” for carbon dioxide. If the concentration of greenhouse gases continues to increase at the rhythm of the last decades, there is the risk that a rapid warming in the Earth’s climate may be triggered, because the capacity of the atmosphere to hold back the heat on the Earth is increasing progressively. An excessive increase in a short period of time, of the temperatures of the atmosphere and of the oceans, would have dramatic effects on the climate balance and a remarkable impact on human beings.
According to some climate experts, if human behaviour does not change, in the next 100 years the Earth’s temperature may increase an  average of 1.0 to 3.5°C.
Other data give us an indication of the variations which occurred in the past century: from the industrial revolution to date, the concentration of carbon dioxide in the atmosphere has increased 30%, during the same period the concentration of methane, emitted principally by the rice fields and cattle farms, has increased 145%. Many experts, appointed by national and international organizations, among which IPCC (Intergovernmental Panel on Climate Change) have, since some years, been monitoring the climate of our planet and studying the possible effects of the increase in temperature of the lower atmosphere and of the Earth’s surface, which will be examined in detail in the following paragraph.