Introduction
Global climatic changes are changes in the climate which affect the entire Earth. With respect to weather changes, which are mostly local and of limited duration, climatic changes interest a large part of the planet and can persist for thousands of years.
We will examine two such global changes, glacial cycles and global warming .
We will introduce glacial cycles first to show how astronomical as well as other factors might influences the climate on Earth. Although ice ages come with a certain regularity, their main cycle lasting 100,000 years, this hasn't been so since the formation of Earth. For example, 50 million years ago, and before, the climate of the Earth was quite different, warmer and with more moisture; the cooling of the Earth is a rather recent phenomenon in its 4.5 billion year history. By looking at this part in some detail, we will
get an appreciation of the complex interaction of various factors in determining
the climate.
see how instabilities in certain phenomena could lead to dramatic changes of
the climate.
examine what kind of evidence scientists gather to buttress their theories.
Global warming is the trend of increasing average temperatures that has been noticed over the last century. The major challange scientists face are:
How good are the data showing this warming trend?
Can this trend be explained as a part of a normal climatic cycle?
Has the release of carbon dioxide due to human activities casued this warming?
If this warming continues, what changes in the climate can we expect?
Is there a danger that this warming sets off an uncontollable spiral of event
which might render most of the planet inhabited?
The answers to some of these questions might have deep consequences for our society, not only in the future, but also presently. If soem of the dire predictions which we will examine are true, this might induce governments to drastic changes in our standard of living in the present time.
This page has been produced by Gianfranco Vidali.