Explore the fascinating world of paleoclimatology in this Emiliani Lecture from the AGU Fall Meeting 2011. Delve into how single-celled organisms serve as invaluable proxies for understanding Earth's climate history. Learn about the evolution of paleocean proxies, their transformation, and their critical role in reconstructing past climate conditions. Discover the contributions of pioneering scientists like Cesare Emiliani, Harold Urey, and others who shaped this field. Gain insights into the carbon cycle, deep-sea drilling, and the two main types of proxies used in paleoclimatology. This comprehensive talk, presented by Henry Elderfield from the University of Cambridge, offers a status report on paleocean proxies, complete with illustrative examples that showcase the power of these microscopic climate historians.