The Climate Trends and Earth Systems Processes chapters (Chapters 2 and 3) of the Fifth National Climate Assessment (NCA5) detail how climate change affects the physical Earth system with a focus on the changes occurring in the United States. The chapters describe the observations we use both to provide clear indications of ongoing climate change and to support advances in the scientific understanding of the Earth system. Descriptions of the current state of understanding of the important physical processes that drive changes in the United States are provided, along with projections of the additional changes we may see in the coming years and decades. This talk outlines the key findings in both Physical Sciences chapters of NCA5 and how they provide a foundation for the other chapters within the report.