SCOPE 21 -The Major Biogeochemical Cycles and Their Interactions 

Foreword

After its initiation in 1974, SCOPE's Project on Biogeochemical Cycles focussed on the study of the cycles of carbon, nitrogen, sulphur, and phosphorus separately, one after the other. It was, however, understood from the beginning that none of these cycles operates in isolation; they are inexorably tied together in one integrated system of cycles comprising many mechanisms of mutual interaction. For meaningful comprehension of this integrated system a study of these interactions would be required; such a study was set as a `target' to which the initial studies on the individual cycles would converge.

The stage for the present study on the interaction of the biogeochemical cycles was set by a series of lectures presented before the 4th General Assembly of SCOPE at Stockholm in 1979 and published in 1981 (SCOPE 17, edited by G. E. Likens). At the Assembly the leadership for the study was entrusted to B. Bolin who forged together an Advisory Committee. This interdisciplinary team played an important role in pulling the threads together.

Following the SCOPE formula, the present report emerged out of draft contributions prepared for and critically discussed at a Workshop held in Örsundsbro, Sweden in 1981.

The report will hopefully serve a dual purpose in providing an up-to-date critical survey of our present knowledge of biogeochemical cycles and their interactions and a perspective of the likely directions that future research in these fields will follow. By its nature the latter aim will at times be more imaginative than rigorous and conclusive.

SCOPE is most grateful to Professor Bolin for the infectious enthusiasm, wise guidance, and highly diverse competence he has brought to bear on this ambitious endeavour. SCOPE is also greatly indebted to all those who in one form or another have contributed to this report. The financial support of UNEP, the U.S. National Committee of SCOPE, the Andrew W. Mellon Foundation, the Mobil Foundation, the Exxon Corporation, and the French Ministry of the Environment is thankfully acknowledged.

Undoubtedly much scientific work remains to be done, but, meanwhile, now that more knowledge is becoming available, the question of how to take action on the basis of this increased perception looms larger and larger. As expressed in the joint statement by M. K. Tolba, Executive Director of UNEP, and G. F. White, President of SCOPE, on Global Life Support Systems (Stockholm, 1979) better comprehension of the system of interacting cycles shall help us

However, better perception of our opportunities and predicaments does not always lead to rational action, and, indeed bringing this about is one of the major problems of the decades ahead. New definitions of the carrying capacity of the earth are gradually becoming formulated and the responsibility of the scientist to help generate new attitudes is greater than ever. The difference between morning and evening may be involved.