A policy for a particular area of society provides a framework for act
ion based on factual information and value judgements. The knowledge b
ase derived from scientific understanding is one important component i
n this context. It is essential for scientists to recognize and commun
icate clearly, and as objectively as possible, the limitations of the
information provided. In this way a truly broad spectrum of scientists
in the field will be represented and a mutual and respectful relation
between scientists and decision makers can develop. The scientist ser
ving in a position of science advisor must acquire insight into other
aspects of the problem under consideration in order to provide the dec
ision maker with the most essential information. He/she must recognize
, not necessarily accept, political or other constraints under which a
decision maker is acting. At the international level, it is necessary
to understand the different value systems that prevail in different c
ultures and which markedly influence the views that are being. These i
ssues are discussed in the context of the political response to advanc
es in our scientific understanding of climate change.