Global Atmospheric Chemical Change

Air pollution has historically been viewed as a local or regional scale problem with attention focused on acute episodes such as the sulphur dioxide and smoke smogs of London in the 1950s and 1960s and the photochemical smogs of southern California first recognized by Haagen Smit in the early 1950s. In recent years, however, it has become apparent that human activity has, and still is, changing the chemical composition of the atmosphere on a global scale. The composition of the atmosphere has seen enormous changes due to natural processes since the formation of the planet. Data obtained from air bubbles trapped in polar ice are beginning to reveal information about these changes over the last tens of thousands of years and geochemical models of the evolution of the Earth give us insights into the changes over much longer periods of time. Perhaps the crucial differences between these natural changes and those now being induced by man are their rel ative rates of change. The magnitude of present day fluxes of some com pounds released as air pollutants is in some cases much larger than those arising naturally. In other cases, for example carbon dioxide, the an thropogenic emission rates are small compared with that of the natural cycle, but the kinetics of the system are such that the steady state concent rations of the compounds in the atmosphere are now being perturbed.

Atmospheric Chemistry and Global Change presents an integrated examination of chemical processes in the atmosphere, focusing on global-scale problems and their role in the evolution of the Earth system. Taking a largely interdisciplinary approach, it features the collective efforts of a group of scientists at the National Center for Atmospheric Research (NCAR), as well as other experts from several universities and national laboratories. Topics discussed include the fundamental physical, chemical, and biological processes that affect the atmospheric composition; the chemical mechanisms that affect the production and the fate of important chemical compounds; and the techniques used to investigate the chemical processes in the atmosphere. The book concludes with discussions on global problems related to the atmosphere (stratospheric ozone depletion, changes in greenhouse gases, and global chemical pollution), the relationship between the atmosphere and the global climate, and the long-term chemical evolution of the atmosphere. Each chapter features a brief essay by a leader in the field and includes a large number of current references. Ideal for graduate courses in atmospheric chemistry and atmospheric science, Atmospheric Chemistry and Global Change also serves as an authoritative and practical reference for scientists studying the Earth's atmosphere. Support materials for the book are available via the website http: //acd.ucar.edu/textbook

Atmospheric Chemistry has been a rapidly growing field with a recent focus on the major aspects of global environmental change, including stratospheric ozone depletion, UV-B change, and global warming. This book describes recent developments in our understanding of the global aspects of the chemistry in the main parts of the atmosphere, troposphere, and stratosphere, as obtained from field observations, laboratory investigations, and modeling studies. Although this chemistry is largely driven by reactions between gas phase species, recent progress made in the understanding of chemical reactions occuring in clouds and on the surface of aerosols is also reported.

Air pollution has historically been viewed as a local or regional scale problem with attention focused on acute episodes such as the sulphur dioxide and smoke smogs of London in the 1950s and 1960s and the photochemical smogs of southern California first recognized by Haagen Smit in the early 1950s. In recent years, however, it has become apparent that human activity has, and still is, changing the chemical composition of the atmosphere on a global scale. The composition of the atmosphere has seen enormous changes due to natural processes since the formation of the planet. Data obtained from air bubbles trapped in polar ice are beginning to reveal information about these changes over the last tens of thousands of years and geochemical models of the evolution of the Earth give us insights into the changes over much longer periods of time. Perhaps the crucial differences between these natural changes and those now being induced by man are their rel ative rates of change. The magnitude of present day fluxes of some com pounds released as air pollutants is in some cases much larger than those arising naturally. In other cases, for example carbon dioxide, the an thropogenic emission rates are small compared with that of the natural cycle, but the kinetics of the system are such that the steady state concent rations of the compounds in the atmosphere are now being perturbed.

Summarizes and integrates more than a decade of atmospheric chemistry research, carried out under the auspices of the International Global Atmospheric Chemistry (IGAC) Project of the International Geosphere-Biosphere Programme (IGBP).

The National Research Council's Committee on Atmospheric Chemistry (NRC/CAC) was established to serve as a focal point for NRC activities on issues related to atmospheric chemical change and its impacts on air quality, climate, stratospheric ozone depletion, and other related issues. The committee consists of 12 members with expertise covering the areas of tropospheric and stratospheric chemistry; urban/regional air pollution; modeling of climate, chemistry, and atmospheric dynamics; in situ and remote sensing observational systems; and interfaces of science and public policy. This CAC study was motivated by a concern that, in the coming decades, dramatic increases in global population and urbanization levels, as well as changes in global climate, may significantly affect air quality over large regions of the globe. The charge to the committee was to examine the linkages among regional/ global changes in atmospheric composition, climate change, and air quality.

This volume contains the invited papers and a transcript of the final panel discussion in the First Scientific Conference of the International Global Atmospheric Chemistry (lGAC) Project, held in Eilat, Israel from April 18-22, 1993. The conference was hosted by the Israeli Institute for Biological Research (IIBR) and was the 37th in the prestigious OHOLO Conference series in Israel. The conference was devoted to the subject of "Global Atmospheric-Biospheric Chemistry" and was a landmark event in this area. It provided the first comprehensive report of progress under IGAC toward improving our understanding of the chemical and biological processes that determine the changing composition of the earth's atmosphere. This work is an essential component of the comprehensive International Geosphere Biosphere Program (lGBP) devoted to measuring and understanding global changes in the past and present, and predicting the future evolution of our planet. I want to devote this brief foreword to thanking several people who worked especially hard to make the conference a success and who helped to produce this volume as a record of the event. Paul Crutzen, Amram Golombek, Pamela Matson and Henning Rodhe did sterling service on the conference organizing committee. Special thanks go to Amram Golombek and Dr. Cohen, the Director of IIBR, who hosted the event in Israel. Anne Slinn did an excellent job in producing the Abstract book and helping with administrative matters. Alex Pszenny helped capably to critically review the Abstracts.

Introduction to Atmospheric Chemistry is a concise, clear review of the fundamental aspects of atmospheric chemistry. In ten succinct chapters, it reviews our basic understanding of the chemistry of the Earth's atmosphere and discusses current environmental issues, including air pollution, acid rain, the ozone hole, and global change. Written by a well-known atmospheric science teacher, researcher, and author of several established textbooks, this book is an introductory textbook for beginning university courses in atmospheric chemistry. Also suitable for self instruction, numerous exercises and solutions make this textbook accessible to students covering atmospheric chemistry as a part of courses in atmospheric science, meteorology, environmental science, geophysics and chemistry. Together with its companion volume, Basic Physical Chemistry for the Atmospheric Sciences (second edition 2000; Cambridge University Press), Introduction to Atmospheric Chemistry provides a solid introduction to atmospheric chemistry.