The Hadley and Walker Circulations are fundamental regulators of the Earthβs energy budget. Although the Hadley Circulation is a well-known concept, surprisingly little attention has been paid to understanding both short and long-term variability of the system. This book reviews current knowledge of Hadley and Walker circulation dynamics and their interactions with the major global monsoon systems, and evaluates paleoclimatic records within the domain of the Hadley Circulation that shed light on past variability of climate over the last 1000 years, the Holocene (the last 11,500 years), glacial periods, and warm climate periods in the past. The book examines potentially important factors that may have affected the Hadley and Walker Circulations on these different time scales and evaluates changes in the Hadley Circulation and the monsoons as simulated by coupled models of past climate conditions, and predicted future conditions under an enhanced greenhouse effect. This book is meant to serve as a fundamental reference work for current and future researchers, graduate students in the atmospheric sciences and geosciences, and climate specialists involved in interdisciplinary research.