A new book edited by Peter Lemke and Hans-Werner Jacobi, Hans-Werner on the history of the Arctic System Study (ACSYS) and ways forward has just been released. ACSYS is the precursor of CliC, so we hope you will all enjoy this great publication.

The ACSYS Decade and Beyond Lemke, Peter; Jacobi, Hans-Werner (Eds.) Atmospheric and Oceanographic Sciences Library, Vol. 43, Springer, Dordrecht, 464 p., 2012.

The most recent minimum in sea ice extent of the Arctic ocean demonstrates that the Arctic is one of the regions on Earth experiencing the most rapid and most severe changes in climate. In the last 20 years, climate change contributed to major physical, ecological, social, and economic changes, many of which have already begun in the Arctic. These changes are expected to accelerate over the next 100 years. Changes in the Arctic climate will also affect the rest of the world through increased global warming and rising sea levels. However, the changes can only be documented if observations and long-term studies of the Arctic exist. Fortunately, a major effort called Arctic System Study (ACSYS) was proposed and conducted by farsighted scientist since the late 1980s. The ACSYS project was the first international collaborative study to observe the Arctic and was supported by several international scientific organizations, riparian states, and further nations like Germany and France promoting research in the Arctic. This book represents an account of this project and its relevance for current Arctic climate research.

The ACSYS project was fundamental in raising the awareness of the role of the Arctic in the global climate system. It has greatly advanced our understanding of the processes acting in the Arctic due to the development of improved observing systems, using both in situ and remote sensing techniques, and numerical models describing the various components of the climate system and their interactions. ACSYS activated nearly 250 scientists from 19 countries for its final conference, with many more researchers, who participated in the respective field work and modeling activities.

The project included a main observational period from 1994 to 2003 to study the structure and the circulation of the Arctic Ocean, the interactions between the atmosphere and the cryosphere including sea ice and the Greenland ice sheet, and the freshwater cycle in the Arctic. ACSYS has provided a valuable legacy of data sets, model components and understanding, which is used as a basis for ongoing research in the Arctic. The book summarizes the results of these coordinated observations that provided the scientific basis for an accurate representation of Arctic processes in regional and global climate models. Major advances in our understanding of the role of the Arctic in the global climate system, its response to large-scale climate variations, and the processes involved are further addressed in the book. Changes in the Arctic are so dramatic that parts of the book are probably already outdated. However, the results can still serve as a reference against which changes currently occurring in the Arctic can be documented.