Covering more than seven percent of the earth’s surface, sea ice is crucial to the functioning of the biosphere—and is a key component in our attempts to understand and combat climate change. With On Sea Ice, geophysicist W. F. Weeks delivers a natural history of sea ice, a fully comprehensive and up-to-date account of our knowledge of its creation, change, and function. The volume begins with the earliest recorded observations of sea ice, from 350 BC, but the majority of its information is drawn from the period after 1950, when detailed study of sea ice became widespread. Weeks delves into both micro-level characteristics—internal structure, component properties, and phase relations—and the macro-level nature of sea ice, such as salinity, growth, and decay. He also explains the mechanics of ice pack drift and the recently observed changes in ice extent and thickness. An unparalleled account of a natural phenomenon that will be of increasing importance as the earth’s temperature rises, On Sea Ice will unquestionably be the standard for years to come.