Environmental Systems [antikvár]

Preface Any book is a compromise between the original aspirations of the author(s) and the realities of publication. For this reason reviewers are often able to take issue not so much with the substantive content of a book, but with pragmatic decisions imposed on authors by this need to compromise. The first edition of this book was no exception, for the breadth of its canvas made compromise inevitable if its focus on functioning environmental systems was not to be lost. Although, hopefully, it has proved to be a successful compromise, several such decisions have been questioned, partly by reviewers, partly by feedback from students and teachers using the book. In opting to concentrate on the human terres- trial environment in the first edition, the nature and role of the oceans was played down. In this current edition that decision has been reassessed, and a new chapter has been devoted to the hydrosphere, thereby acknowledging the import- ance of the oceans in an understanding of the energetics and biogeochemistry of the planet. Similarly, the decision to model the structural and functional organization of the biosphere at the molecular and cellular level, although valid in itself, has also been reassessed, because those readers who constitute the main market for the book are more concerned with the macroscopic properties of the biosphere. In consequence the biosphere and ecosphere chapters have been condensed into one, allowing an expanded treat- ment of biogeochemical cycling and the perturba- tions to these cycles occasioned by human activity (with some small loss of the perspective provided by cell biology on the nature of the biosphere). New chapters dealing with two environments the understanding of which is of profound im- portance to current environmental problems have been added, mainly in response to reviewers' comments. The first (Aeolian systems) underpins the understanding of desertification and the en- vironmental problems of arid and semi-arid lands. The second (Coastal systems) considers the phys- ical and biological systems that straddle the inter- face between land and sea. During the life of any edition of a book, the field it purports to consider will itself evolve and develop, as does its social and cultural context. New research findings enhance understanding or open new avenues of endeavour, which, with in- ductive reasoning, extend the frontiers of the field. New paradigms emerge, and private and public attitudes and values change. In short, a book is an ephemeral entity, providing at best a synoptic picture: a particular view of the world which is sooner or later out of date and superseded. The first edition of this book, however, was fortunate in being a little ahead of its time in anticipating some of the changes which have occurred since its publication. The preface to the first edition stated that in the environmental sciences the systems philosophy had abandoned its ivory tower to become public property with the rise of environ- mentalism. Though fundamentally true, that state- ment was slightly premature for it turned out that the public required time to become aware of what they had acquired, and learn what to do with it. However, the recognition of the depletion of the ozone layer, and the accelerating debate sur- rounding the threat of global warming changed the status of the environmental and green agenda from parochial and regional issues to global imperatives. Against the background of these changes, for the first edition to have concluded with the hope that politicians and governments would develop an informed picture of their environment through which to formulate and implement policy, seems prophetic indeed. Never- theless, the first edition has stood in need of re- vision, first, in recognition of the vastly increased awareness of environmental issues in general, and of the systems approach to environment in particular, and secondly, to catch up with recent developments. All the chapters have been revised (some ex- tensively, for example that dealing with the glacial system), and updated in line with developments in the appropriate disciplines since the time of the original publication. Recent work has been incorporated within the redrafted text (see, for example, material on the greenhouse gases), and/ or appears in new boxed material as appropriate (see new Box on Stream power and the fluvial system). The geophysical and geochemical view