The interdisciplinary study of paleoclimates is symptomatic of how the climate and earth sciences represent a matured practice of pragmatically dealing with purely heuristical strategies and implicit uncertainties. Both have not only become important providers of crucial data for decision making in contemporary societies but are also becoming role models for other sciences. To give an epistemic framework for this new prestige, the paper ﬁrst focuses on three interconnected conceptual terms that are central to paleoclimatology: the earth itself as an experimental setting that has recorded deep-time climatic events, which could serve as geological analogues to assess the current rapid transition from the Holocene into the Anthropocene. In order to demonstrate the historical foundations of such a rationale, the paper then explores the history of proxy-data generation and analysis by focusing on the development of paleoceanography – a critical discipline in forming a deep-time perspective on climate history. By highlighting the technology-driven transformations of this field during the era of the great oceanographic expeditions and the start of stable isotope analysis in the aftermath of World War II, it argues for a strong historical continuity of the epistemic framework of paleoclimatology.