Foreword

Abstract
Earlier this year, with the opening of the 2002 session of the European Research Course on Atmospheres ("ERCA") we celebrated the occasion of the tenth anniversary of ERCA, in the presence of Hubert Curien, President of the French Academy of Sciences and former Minister of Research, Paul Crutzen (1995 Nobel Laureate for Chemistry), Claude Feuerstein (President of University Joseph Fourier of Grenoble) and Philippe Gillet (Director of the National Institute for Universe Sciences). More than 450 participants from 40 different countries in Europe, Asia, America and Africa attended the ten organized sessions, confirming the success of this interdisciplinary course whose characteristics still remain rather unique.

Of particular importance for this success, was the publication of a series of books which are the tangible products of the course material. Four books were published in 1994, 1996, 1998 and 2000. They are made up of chapters which present up to date overviews of our present knowledge in a wide range of topics, written by ERCA lecturers who are recognized specialists in these different fields.

This volume is the fifth in the series. After an introductory chapter in which Paul Crutzen propounds to name "anthropocene" the present period characterized by the ever increasing impacts of human activities on our environment, it contains nineteen chapters surveying various topics "From the impacts of human activities on our climate and environment to the mysteries of Titan ". Particular emphasis is given to the origin of life on Earth, climate change, atmosphere modelling, climate-vegetation interaction, deep sea records of past climate variability, the last glacial maximum, halogen chemistry in the marine boundary layer, the role and fate of trace elements in the environment, mercury as a global pollutant, atmospheric aerosols, emissions of pollutants in Europe, the effect of atmospheric pollution on building materials, air quality assessment, transport phenomena in the atmosphere, the solar energetic flux, the atmosphere of Saturn's satellite Titan, cometary research, molecules and the process of star formation.

It is a pleasure for me to acknowledge the excellent efforts and cooperation of our distinguished group of contributors, who kindly gave some of their time to write the chapters and survived the pressure I put on them to meet the deadlines. I am also particularly grateful to Isabelle Houlbert and Laurence Castagné for editorial assistance and their enthusiasm for "eclairs au café". Last but not least, very special thanks are due to Michèle Poinsot for her continuous and expert efforts over so many years to make ERCA such a success, and also for her friendliness for more than twenty five years.