Continuing and updating the Encyclopedia of Water Science over the past four years has been an exciting but daunting task. It has been exciting because the subject is so critical to life and living, and daunting because the original editors set such a high standard. As ever, water is the central focus in environmental science. In addition to all the critical factors cited in the Preface to the first edition, global warming has now become more certain so that water issues will become even more important
