The climate is a common good, belonging
to all and meant for all. At the global level, it is a
complex system linked to many of the essential
conditions for human life. A very solid scientific
consensus indicates that we are presently witnessing
a disturbing warming of the climatic system.
In recent decades this warming has been accompanied
by a constant rise in the sea level and, it
would appear, by an increase of extreme weather
events, even if a scientifically determinable cause
cannot be assigned to each particular phenomenon.
Humanity is called to recognize the need
for changes of lifestyle, production and consumption,
in order to combat this warming or at
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least the human causes which produce or aggravate
it. It is true that there are other factors (such
as volcanic activity, variations in the earth’s orbit
and axis, the solar cycle), yet a number of scientific
studies indicate that most global warming in
recent decades is due to the great concentration
of greenhouse gases (carbon dioxide, methane,
nitrogen oxides and others) released mainly as a
result of human activity. As these gases build up
in the atmosphere, they hamper the escape of
heat produced by sunlight at the earth’s surface.
The problem is aggravated by a model of development
based on the intensive use of fossil fuels,
which is at the heart of the worldwide energy
system. Another determining factor has been an
increase in changed uses of the soil, principally
deforestation for agricultural purposes.
24. Warming has effects on the carbon cycle.
