Environmental Engineering Reference
The Climate Before
We have known for a long time that the climate is changing. Numerous ice ages
and warming periods have shown that the climate on earth is constantly undergoing
change. In terms of human lifetimes, each of these periods lasted a relatively long
period of time. In the more recent history of the earth, ice ages have occurred about
every 100 000 years, always interrupted by much shorter warming times. Our current
warming period, called the Holocene era, began about 11 700 years ago. As the
previous warming periods on average lasted only about 15 000 years, we should be
heading towards the next ice age.
The exact causes for the alternation between warming and ice ages can only be
reconstructed to a point. Natural effects, such as changes in solar activity, changes
in the geometry of the earth's orbit, vulcanism, changes in the ocean currents and
the shifting of continental plates are considered the main causes of climate change.
When multiple causes occur at the same time, very abrupt changes are possible.
This explains the climate changes of the earth. In this sense, the global warming
that we have observed in recent years is nothing out of the ordinary. What is unusual
is that apparently for the fi rst time it is living things on earth - namely, human
beings - that are causing an abrupt change in climate.
2.1 It Is Getting Warm - Climate Changes Today
2.1.1 The Ice is Slowly Melting
Climate conditions on earth have been relatively constant for several thousand years.
It is on this basis that our civilization, the places where we have settled and our
agricultural regions have established themselves. During the last ice age areas that