Headlines around the world about severe droughts, hurricanes, and floods caused by El Ni o and La Ni a appear every few years. El Ni o is the second most important climate process after the changing seasons; its effects are widely known, but the equally serious impact of La Ni a is only now beginning to be appreciated. Fully revised, Currents of Change clearly explains what El Ni o and La Ni a are and how they can be forecast. Examining for the first...