Advancements in knowledge about sea surface temperature (SST) at key points in Earth's past are on the horizon through a new research project called TEMPUS that is funded by the European Commission's Environment and Climate Programme. The first priority of the project is to reconstruct the last ice age, which serves as a stringent test for appraising the validity of climate models. SST data for this effort are being obtained from the Climate/Long-Range Investigation, Mapping, and Prediction (CLIMAP) project 18 kyr reconstruction [CLIMAP, 1976, 1981]. CLIMAP represented a turning point in the study of climate change and helped to fuel explosive growth in climate research based on the analysis of sediment cores. Maps produced 20 years ago from CLIMAP data are still at the core of much groundbreaking research.