W. G. Rees is a senior lecturer at the Scott Polar Research Institute, University of Cambridge, where he has taught and researched in the field of remote sensing for over twenty years. He has been active in developing and applying remote sensing methods to the mapping and monitoring of the polar regions, having conducted fieldwork in arctic regions of Europe and Asia and in Svalbard. For the past few years he has been joint coordinator of PPS Arctic, a major programme to investigate the characteristics and behaviour of the arctic treeline as part of the International Polar Year, and he is also a member of the ISPRS (International Society for Photogrammetry and Remote Sensing) working group on LiDAR. Dr Rees has published several books on remote sensing, including the first and second editions of Physical Principles of Remote Sensing (1990, 2001, Cambridge University Press), The Remote Sensing Data Book (Cambridge University Press, 1999) and Remote Sensing of Glaciers (with P. Pellikka, Taylor and Francis, 2010). He was made a Fellow of the Institute of Physics in 1996 and is a member of the Photogrammetry and Remote Sensing Society.