The Arctic is now experiencing some of the most rapid and severe climate change on earth. Over the next 100 years, climate change is expected to accelerate, contributing to major physical, ecological, social, and economic changes, many of which have already begun. Changes in arctic climate will also affect the rest of the world through increased global warming and rising sea levels. The volume addresses the following major topics: - Research results in observing aspects of the Arctic climate system and its processes across a range of time and space scales - Representation of cryospheric, atmospheric, and oceanic processes in models, including simulation of their interaction with coupled models - Our understanding of the role of the Arctic in the global climate system, its response to large-scale climate variations, and the processes involved.

The Arctic can be viewed as an integrated system, characterised by intimate couplings between its atmosphere, ocean and land, linked in turn to the larger global system. This comprehensive, up-to-date assessment begins with an outline of early Arctic exploration and the growth of modern research. Using an integrated systems approach, subsequent chapters examine the atmospheric heat budget and circulation, the surface energy budget, the hydrologic cycle and interactions between the ocean, atmosphere and sea ice cover. Reviews of recent directions in numerical modelling and the characteristics of past Arctic climates set the stage for detailed discussion of recent climate variability and trends, and projected future states. Throughout, satellite remote sensing data and results from recent major field programs are used to illustrate key processes. The Arctic Climate System provides a comprehensive and accessible overview of the subject for researchers and advanced students in a wide range of disciplines.

The high latitudes of the Arctic and Antarctic, together with some mountainous areas with glaciers and long-lasting snow, are sometimes called the cryosphere-defined as that portion of the planet where water is perennially or seasonally frozen as sea ice, snow cover, permafrost, ice sheets, and glaciers. Variations in the extent and characteristics of surface ice and snow in the high latitudes are of fundamental importance to global climate because of the amount of the sun's radiation that is reflected from these often white surfaces. Thus, the cryosphere is an important frontier for scientists seeking to understand past climate events, current weather, and climate variability. Obtaining the data necessary for such research requires the capability to observe and measure a variety of characteristics and processes exhibited by major ice sheets and large-scale patterns of snow and sea ice extent, and much of these data are gathered using satellites. As part of its efforts to better support the researchers studying the cryosphere and climate, the National Aeronautics and Space Administration (NASA)-using sophisticated satellite technology-measures a range of variables from atmospheric temperature, cloud properties, and aerosol concentration to ice sheet elevation, snow cover on land, and ocean salinity. These raw data are compiled and processed into products, or data sets, useful to scientists. These so-called "polar geophysical data sets" can then be studied and interpreted to answer questions related to atmosphere and climate, ice sheets, terrestrial systems, sea ice, ocean processes, and many other phenomena in the cryosphere. The goal of this report is to provide a brief review of the strategy, scope, and quality of existing polar geophysical data sets and help NASA find ways to make these products and future polar data sets more useful to researchers, especially those working on the global change questions that lie at the heart of NASA's Earth Science Enterprise.

Major international, interdisciplinary research programmes are now underway to increase our understanding of how the Earth System operates and how it is changing through the effects of human activities. Although understanding and predictive capacity are still limited, scientists already agree that significant global changes must be expected in the next 50 years that will affect the capacity of the Earth to sustain life. Governments, business and industry have, therefore, come to recognize that scientific knowledge about the changing global environment - as yet incomplete but rapidly evolving - is becoming indispensable for wise long-term policy making, the goal being to design preventive, adaptive and remedial measures. Thus global change science and policy making are engaged in a process of forming a new partnership that is taking shape as further insights evolve. Effective continuous interactions between the partners requires mutual understanding: decision-makers need to understand the unique potential but also the limitations of the results of scientific research in progress while scientists must take into account the priorities and constraints of policy-makers in designing and implementing policies that will promote long-term sustainability of life on this planet. This book contributes in a unique manner to this mutual understanding: It gives an overview of the ongoing relevant research focusing on the two major international programmes, the International Geosphere-Biosphere Programme and the World Climate Research Programme. These are described in terms understandable to the interested lay reader. The results of the latest review of the Intergovernmental Panel on Climate Change (IPCC) are included. This is followed by an analysis of the response process that is in progress with respect to governments - singly and multilaterally - by business and industry and by public interest groups. This process is leading to interactive structures, assessment procedures and legislation, nationally and internationally. Business and industry are changing from mere watchfulness to recognition of new opportunities for products and processes. Six interviews with prominent figures from business and government circles in the Netherlands provide a vivid illustration of the questions at issue. The appendices provide overviews of methods for incorporating the results of global change science into policy-making and development of long lasting projects. Adaptation to climate change serves as an example. Thus, for the first time, one book describes both ongoing research work in global change and the response processes that the research results are evoking. It is of interest to all stake-holders in the scientific community as well as to decision-makers in industry, business and government.

Following a decision by the Arctic Ocean Sciences Board (AOSB) in July 1996 the then chainnan, Geoffrey Holland, wrote a letter of invitation to a meeting to plan a "Symposium on the Freshwater Balance of the Arctic". The meeting was held in Ottawa on November 12-13 1996 and was attended by representatives of various organisations, including the U.S. National Science Foundation (NSF), as well as individual scientists. Results of this meeting included: • Co-sponsorship with AOSB by the Scientific Committee on Ocean Research (SCOR), the Arctic Climate System Study (ACSYS) and the Global Energy and Water Cycle Experiment (GEWEX). • A decision to apply for funding as a Advanced Research Workshop (ARW) of the North Atlantic Treaty Organisation (NATO) Scientific Affairs Division. • That expenses would be covered in part by funds available through an existing NSF grant to the SCOR Executive offices in Baltimore, MD. • The appointment of myself to be Chairman/Manager for the Symposium. • Provision of a recommended list of Scientific Advisors to assist the Chainnan in selecting key speakers.