Sir John Houghton's comprehensive introduction to climate science explains the physics of the greenhouse effect, the evidence for human-caused warming, and the projected impacts of continued emissions. Houghton, who chaired the Intergovernmental Panel on Climate Change's scientific assessment working group, writes with authority about both the science and the policy implications. The book proceeds systematically from basic atmospheric physics through paleoclimate evidence, contemporary observations, climate modeling, and projections for different emissions scenarios. Houghton addresses common misconceptions and skeptical arguments with scientific precision rather than political dismissal. His treatment of impacts covers sea level rise, extreme weather, ecosystem disruption, and human consequences including migration and conflict. The policy chapters examine mitigation strategies, from energy efficiency to renewable power to carbon capture, providing realistic assessment of what different approaches might accomplish. This fifth edition incorporates the latest IPCC findings and updates projections based on recent research. Houghton writes accessibly without sacrificing scientific accuracy, making complex systems understandable to general readers while remaining useful for students and professionals. The book serves both as introduction for those wanting to understand climate science and as reference for those needing authoritative summaries of specific topics. In an era of climate denial and confusion, Houghton provides the scientific foundation necessary for informed citizenship.