SCOPE 29 - The Greenhouse Effect, Climatic Change, and Ecosystems

Preface

The problems of the increasing atmospheric carbon dioxide concentration and possible future climatic changes have attracted considerable attention in recent years. A number of assessments of this problem have been made by national groups, notably in the United States. The problem is clearly an international one and an assessment at the international level therefore seems desirable to serve as a basis for discussion and possibly, at some stage, for the development of an action plan. The present analysis is aimed at serving such a purpose and is the result of an agreement between the United Nations Environment Programme (UNEP), the World Meteorological Organization (WMO) and the International Council of Scientific Unions (ICSU), the organizations which jointly implement the World Climate Programme.

In the present assessment the following major questions have been considered:

• How much CO₂ has been and will be released into the atmosphere as a result of fossil-fuel combustion (Chapter 2)?

• What are the natural sources and sinks of carbon (the global carbon cycle) and what projections can be made of future atmospheric CO₂ concentrations (Chapter 3)?

• What are the expected increases of other greenhouse gases that affect the Earth's radiation budget (Chapter 4)?

• How will global and regional climates change as a result of increases in CO₂ and and other greenhouse gases (Chapter 5)?

• When and how will climatic changes be detected? Is it possible to design climate scenarios which can be used for climate impact studies (Chapter 6)? 

• What changes of sea level can be expected as a result of a warming of the atmosphere (Chapter 7)? 

• What are the responses of terrestrial ecosystems to direct effects of an increased atmospheric concentration of CO₂ and climatic change (Chapters 8, 9 and 10)?

For each one of these questions one or a few well-recognized scientists have been asked to summarize our present knowledge and, in doing so, also to present the main uncertainties and controversial opinions that exist. These contributions have been exposed to critical reviews by panels of scientists in respective fields who have expressed their views either during panel meetings, by correspondence or in direct personal contact with the authors. The aim has been to arrive at analyses of the different aspects of the problem areas that describe current knowledge in a balanced and well-documented manner. 

Chapter 1 is intended to address these more general problems based on the detailed presentations in Chapters 2, 3, 4, 5, 6, 7, 8, 9 and 10. Such an analysis certainly can be written in many different ways depending on how our present knowledge is evaluated. The present effort is aimed at giving a balanced overview and at indicating major controversies.

With these presentations as a background the UNEP/WMO/ICSU International Conference on the Assessment of the role of carbon dioxide and of other greenhouse gases in climate variations and associated impacts at Villach, Austria, in October 1985 could be devoted primarily to discussions of 

• How to deal with the major uncertainties in our factual knowledge base, which will probably not be significantly altered until a change has been observed. 

• The nature of international collaboration and action that might be necessary now, on the basis of present knowledge, or later, when more information has become available. 

• Research priorities to provide the best possible knowledge about the results of man's future exploitation of his natural environment and their impact on climate on Earth. 

Included in the present volume is also the Conference Statement from the conference at Villach, which is aimed at serving the nations of the world and the international organizations concerned in their further attending to the problem of possible future man-induced changes of the global climate.

The assessment has been carried out at the International Meteorological Institute in Stockholm with the participation of a large number of scientists, who are listed at the beginning of each chapter. Their devoted work to complete the task is gratefully acknowledged.

We also wish to thank Ingrid Gustafson and Benita Wahlström for their secretarial assistance.

Financial support for the conduct of the present assessment has come primarily from the United Nations Environment Programme (UNEP). Major contributions have also been given by the World Meteorological Organization (WMO), the Scientific Committee on Problems of the Envirornment (SCOPE/ICSU), the World Resources Institute (WRI) Washington, DC (USA), the Swedish Board for Energy Research (Energiforskningsnämnden and by the International Meteorological Institute in Stockholm.