This book describes how Milankovitch cycles work, that is, how slight variations in Earth's rotation and orbit cause ice ages. Over tens of thousands of years, changes in the eccentricity of Earth's orbit, the degree of tilt in its rotational axis, and precession (the direction of that tilt over the course of a year) affect the amount of sunlight reaching high (about 65 degrees N) northern latitudes in the summer relative to what it receives in the winter. When seasonality of insolation is low, Canada, Greenland and Scandinavia have mild winters, but cool summers. It still snows a lot, but less of that snow melts away, and the portion that remains can help glaciers grow into ice sheets and ice sheets to spread, in turn creating more feedbacks that help the ice to grow even more.
ISBN 0-89490-015-3
find it in: Worldcat (for local availability) and Amazon.com [check Library of Congress]
