Chapter 3 explores the question: how are instrumental and paleoclimate records used to document and interpret recent climate changes? This exploration begins by distinguishing external climate forcing factors from climate variability internal to climate system spheres, and by recognizing the challenges of separating internal variability effects from longer-term climate trends. Characteristics and limitations of instrumental climate records are discussed, and are compared with the characteristics and limitations of proxy paleoclimate data interpreted from natural archives. The value of “splicing” (connecting and combining) instrumental and proxy climate data to help calibrate the proxy data and to produce long-term continuous climate records is demonstrated, and illustrated using examples of the Little Ice Age, as well as changes in Arctic sea ice cover and changes in atmospheric temperatures during the past 2000 years.