Book excerpt: Written by more than 70 scientists from around the world, this publication assesses the state of the environment and the trends in ice and snow-covered regions (the cryosphere). It looks at the significance of climate changes for ecosystems and human well-being, both now and in the years to come, given that changes in ice and snow alter the distribution of the earth's heat and water, and influence regional and global ocean circulation. This publication is an official project of the International Polar Year 2007-2008.