Snow and Climate: Physical Processes, Surface Energy Exchange and Modeling Edited by R.L. Armstrong & E. Brun Cambridge University Press, Cambridge, 2008 ISBN 9780521854542, 256 pages, £65

Eocene Thermal Maximum and Eocene–Oligocene greenhouse to icehouse transition. The Oligocene–Miocene boundary is characterized by a shift toward cooler climates and Pfuhl & McCave discuss the importance of opening of seaways and the inception of a full Antarctic Circumpolar Current. The Miocene was a critical time of palaeoceanographic reorganization in which the closure of the Panama Isthmus played a key role. Schmidt reviews causes and consequences of the closure of the Central American seaway and provides a comprehensive compilation of both marine and terrestrial proxy data. The book ends with a paper by Ravelo et al. reviewing marine proxy evidence for Northern Hemipshere glaciation and the role of a shoaling thermocline as a critical threshold. The book is a very successful attempt to marry the signal from computer models and biological proxies. However, it also gives the impression that in deep-time palaeoenvironmental science, climate modelling is clearly the weaker partner in this young marriage. Only about five articles of the book have a clear focus on climate simulations and data-model comparisons, whereas many contributions of “data collectors” only marginally refer to climate models. Deep time modelling is a challenging task, as the number of proxy data for boundary conditions strongly decreases with geological age. Therefore, in contrast to the Quaternary, the number of “deep-time” modellers is rather limited. Sohl & Chandler provide a challenging and careful combined data/model approach to simulate Neoproterozoic palaeoclimate. Kiehl describes opportunities and limitations of computer models simulating Late Palaeozoic palaeoclimates. Haywood et al. give a comprehensive overview on their mid-Pliocene climate modelling exercises, which clearly demonstrates the rapid progress in deep-time modelling and data-model comparison techniques in recent years. Markwick gives impressive examples of how biological proxy data can be processed and synthesized in a Geographical Information System to define climate boundary conditions and facilitate data-model comparisons. Hill et al. presents not only a new Pliocene model of the mid-Pliocene East Antarctic Ice Sheet, but also a thorough data-model comparison for Polar Regions. In conclusion I can highly recommend this book to anyone who is interested in getting a comprehensive overview of deep-time palaeoenvironments and climate modelling. The book is very useful for “data collectors” who need an update or summary on state-of-the-art deep time geology and also to modellers for whom it provides a rich source of data to validate and test their simulations. Given the differences in scientific approaches, languages and techniques, the liaison between “data collectors” and modellers represent a major challenge for both scientific communities. Despite these difficulties the editors succeeded in producing a coherent and valuable publication, which is a promising start to a hopefully happy and long-lasting relationship. ULRICH SALZMANN