In a remarkable monograph, Roy W. Spencer presents hard evidence that 75% of the observed warming since the start of the 20th century is due to natural processes. He offers a detailed model describing how one of these processes, the Pacific Decadal Oscillation (PDO), operates in the real world. Most importantly, he demonstrates that anthropomorphic global warming (AGW) is a minor contributor to a global climate largely insensitive to man-made CO2.