The age of the water in the world’s oceans is critical for understanding ocean circulation, especially for the transport of gases from the atmosphere into the deep ocean. Researchers from Heidelberg University recently used an atomic physics technique they developed to determine the age of deep ocean water ranging from 50 to 1,000 years. This new dating method, which measures individual argon atoms, was used in a pilot study in the North Atlantic. The experiments are part of an interdisciplinary project with oceanographers of the GEOMAR Helmholtz Centre for Ocean Research Kiel. The results were published in the journal Nature Communications.