The Intergovernmental Panel on Climate Change Fourth Assessment Report (2007) acknowledged that current ice sheet models do not adequately treat the dynamic response of ice sheets to climate change. This second edition addresses these issues through the addition of new chapters covering glacier instabilities, the interpretation of observations, and ice sheets and sea level. Another new chapter covers glacier mass balance. The text also provides the necessary background and theoretical foundation for developing more realistic ice sheet models, which is essential for better integration of data and observations as well as for better model development.