Introduction
variability and to identify trends. In chapter two it is tried to make a synthesis of
earlier work and to set the scene for the more detailed contributions that follow.
Chapter three presents a wider perspective looking at the relevance of climate data
for other environmental research such as for desertification studies and in the
agricultural area. In view of what has been said before about the linkage between
empirical data and nature the question is addressed which data are best suited as
"indicators" of changes. Indicators are measured state variables by which changes
can be quantified. This concerns the whole range of environmental quantities, not
exclusively climate variables but in addition those quantities which depend on climate
respectively ref1ect the impact of climate on the environment. Next, in chapter four,
large scale climatic phenomena are discussed. This is followed by a presentation of
regional climatic variability in chapter five. Papers on the changes observed in the
Mediterranean Sea and of the interaction between the surface and the atmosphere
follow in chapter six. Finally examples are presented in the seventh chapter.
Experimerntal approaches are addressed to monitor atmospheric state variables which
are not operationally measured and networks are described which address specific
environmental questions and gather data.